masik summer 2015

8/19/2019 Masik Summer 2015

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ISSN: 19464657

ContentsIn This Issue, ii

Editor’s Letter, iv

Greenland Kayaking, Argentina Style, 1

Deconstructing Greenland Kayaks, Part III:

The Mighty Keelson—Results of Destructive Testing, 7

Deconstructing West Greenland Kayaks Part IV:Hull Design Part One: Form Follows Function, 21

The “Hand of Pavia” Rescue – Defined, 35

Greenland* Moves Southward

*Greenland paddlers, that is!, 39

Adam Hansen Qajaq Models, 44

Deconstructing Greenland Kayaks: Form Follows Function, Part 2, 46

Indexes, 75

Acknowledgments, 88

Summer 2015

A qajaq in Aasiaat, Greenland Photo: Adam Hansen


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IN THIS ISSUE This issue begins with Joanne Barta’s account of her trip to Argentina in the Spring of 2011, when she participated in

the first South American Traditional Qajaq Symposium. She documents her experiences with lively text and wonder-

ful photos. Even when the spoken languages of the participants are different, they have the language of kayaking —

building and paddling — in common.

Ralph Young again applies an engineer’s perspective to his study of kayak design, which he supplements with mod-

el testing. His first article documents destructive testing of two kayak frames — one with a keelson, one without —

conducted at the 2013 Delmarva Paddler’s Retreat. Ralph makes the case that the keelson is central to the strength

of the kayak frame. His second article explores hull design, and the third follows up with testing of scale models of

a variety of watercraft done at the 2014 Delmarva Paddler’s Retreat. Ralph submitted each article to a number of

people with experience designing boats or extensive knowledge of Arctic watercraft and provides their feedback

and his responses to it. The articles aren’t without controversy, but Ralph’s willingness to report the comments and

offer his responses are a model for scientific research.

If you’ve been to one of the Qajaq USA events over the last few years, chances are you’ve seen a variety of assisted

rescue demonstrations, among them the Hand of Pavia rescue, a term used to refer to the variation of the “Hand-of-

God” rescue that was taught by Pavia Lumholt at SSTIKS 2005. John Doornick and Henry Romer allowed us to reprint

their informative article, along with instructions for making an Oscar rescue dummy to use for practice, during those

times when a living victim is unavailable or unwilling.

The newest Qajaq USA event, the Traditional Inuit Paddlers of the Southeast, or TIPS, was conceived by Fran Symes

and Fern White as they drove to the Delmarva Paddler’s Retreat on a cold, blustery weekend in October 2013. In her

article, Fran describes how the idea came to fruition the following May at Camp Bob Cooper, on the shores of Lake

Marion, in Summerton, South Carolina.

Adam Hansen, resident of Aasiaat, Greenland, and frequent guest at Qajaq USA events, here graciously shares pho-

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tos of some of the models he has made over the winter months in Greenland. We are proud to feature one on the

cover.

Rounding out this issue are two indexes to every article published in The Masik, excluding this issue. The first groups

articles by 13 categories, ranging from accessories to travel, chosen to reflect the content. The second lists articles

by author’s last name. These indexes show the great breadth of articles published since the first issue of The Masik

came out in 2003.

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EDITOR’S LETTERI’ve been thinking about how the traditional paddling community has evolved during Qajaq USA’s existence — how

what was once a far-flung group of paddlers linked by the Qajaq USA forum, the Delmarva Paddler’s Retreat, and the

Masik has become connected through Facebook, personal and business websites, and numerous Qajaq USA events.

Editor Bobby Curtis’s wonderful first issues of the Masik captured the enthusiasm of builders and rollers who wanted

to share their knowledge, back when there weren’t any DVDs or YouTube videos detailing all the competition rolls

and rope maneuvers. Later issues offered book reviews and interviews with people who had, and have, strong con-

nections to Greenland kayaking, as well as personal reflections on individual kayaks and analyses of kayak design.

The upside of this is, with so much information readily available via the World Wide Web, anyone having an Internet

connection has unprecedented access to knowledge that 15 years ago required travel to get. And the Qajaq USA

forum archives are a more focused resource, having over a decade’s worth of Greenland-kayak-related information

available via the search function.

The downside to this is that both the Masik and the forum seem less vital parts of the traditional paddling commu-

nity than they once were. From my perspective as editor, content has been harder to come by. I used to solicit a few

articles per issue, and several unsolicited ones would be sent to me. This issue isn’t an exception, but the difference

is that what used to take a few months to gather has taken over a year. At the same time, the number of posts on the

forum is down, perhaps because many building and paddling techniques have been so well described on the forum

itself or elsewhere, there just isn’t as much to talk about. Or perhaps these conversations are still going on, but on

Facebook and other websites.

On the other hand, there are now six Qajaq USA sanctioned events: Delmarva Paddler’s Retreat, SSTIKS (South

Sound Traditional Inuit Kayaking Symposium), TIPS (Traditional Inuit Paddlers of the Southeast), HRGF (Hudson River

Greenland Festival), Michigan Training Camp, and Traditional Paddlers Gathering — which suggests that the tradi-

tional paddling community is healthy and growing.

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So how does the Masik stay relevant? I think that it needs to be published more frequently and be more connected

to social media to better capture events as they happen. What it will look like will be up to the next editor, as this is

my last issue.

I’m proud to have been a part of the Masik these last ten years. Working on it has been more satisfying than nearly

everything I’ve done professionally. I’ve especially enjoyed collaborating with the authors — it’s difficult to express

how grateful I am to work with people who truly care about their subjects, except to say that their passion has been

inspiring.

In closing, I’d like to say thank you to Bobby Curtis and Tamara Hanks, the Masik’s first editor and art director, whose

standards guided me; the art directors I’ve worked with, Thomas Duncan, Alison Sigethy, and Helen Wilson, each

of whom put their own stamp on the design of the Masik; and proofreaders Bill Price, Wes Ostertag, Jane Taylor,

Alison Sigethy, Len Thunberg, Bonita Martin, Helen Wilson, Ginger Travis, and Tracy Coon, all of whom improved the

articles they read.

My wife, Alison, our friend James Song, and I went to Greenland for the competition in 2006. Near the end of our

stay, our new friend Najannguaq said, “I won’t say goodbye because maybe I’ll see you again.” To everyone who

reads this, these are my thoughts as well.

Qujanaq

Tom Milan

May 2015

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N E W S L E T T E R o f Q A J A Q U S A — t h e A M E R I C A N C H A P T E R o f Q A A N N A T K A T T U U F I A T

Greenland Kayaking, Argentina Style

by Joanne Barta

Background

In the spring of 2011 I traveled to Argentina to participate in the first South American Traditional Qajaq Symposium.

I had heard about the event, or plans for such an event, about six months before that when my friend, Don Beale,

was invited to teach a paddle-carving class there. There was to be a week-long class building skin-on-frame kay-

aks, led by Eiichi Ito from Japan; ropes and rolling sessions taught by Dubside; and an ACA Level 3 IDW and ICE (an

instructor development workshop and instructor certification exam that is part of the American Canoe Association

series of instruction; (see www.americancanoe.org for more information) led by Christian Fuchs and Fabio Raimo.

Then a large celebration on Saturday and Sunday to showcase the kayaks, paddles, skills learned, and of course lots

of fabulous food.

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The event was organized by Rony Maier, with support from Paul Deiner. Rony had traveled two years before to at-

tend The LoCo Round Up, a week-long paddling symposium hosted by Ginni Callahan and Columbia River Kayaking

in Skamokawa, Washington. He returned to Argentina inspired.

Here was an incredible opportunity for me to do the two things I most like doing: traditional paddling and travel.

What’s more amazing is that the symposium exactly coincided with my elementary school’s spring break! It seemed

meant to be.

The symposium was held at a beach along the Las Aranas river, a branch of the Parana River, in the town of Valle Ma-

ria, a few hours’ drive northeast of Buenos Aries. The Parana river is wide and warm, with a very fine silt suspended

in the water giving it a chocolate color. One day it would be flat, the next day white caps would provide some excite-

ment for paddlers. I was met at the airport by two avid paddlers and their kayaks. They drove us to the park and

gave us tents. My tent was near the group from Rio Mistico, who were taking their ICE. Every morning they would

be up about six, drinking yerba mate and nibbling on fruit and dulce leche (think caramel candy) on saltines. These

folks don’t eat breakfast. But daily a multitalented man in a white truck arrived selling bread, cheese, salami, and

jam. I bought these as well as pastries from the small store to share with my new friends. They, knowing how North

Americans love their coffee, bought Nescafe for me. We would spend an hour or so around the concrete picnic table

eating, drinking, making jokes. Most of them spoke Spanish, English, and Portuguese.

Work Begins

Meanwhile, Eiichi was at the community shelter that doubled as wood shop and dining hall. His class of eight

students began each day at 8 a.m. A chalk board outlined the plan for the day, complete with drawings. Everyone

brought their own tools, but sharing was the norm. When I arrived they had been hard at work for just one day. The

gunwales were sprung and deck beams were fitted. There was a table with snacks. Eiichi brought crackers and sea-

weed from Japan to share. Others brought cookies, cheese, and sausage. And of course, there was yerba mate.

That week there were 25 of us working on kayaks, preparing and carving paddles, or training for the ICE. At 1 p.m.

each day we stopped for lunch. We sat at one long table. Chefs cooked and served a variety of truly delicious meals

for us: beef ribs with potatoes; broiled fish; pasta with meatballs; roasted chicken. The yerba mate gave way to quart

bottles of beer, which we bought at the park store and shared. We would dine for two hours, then return to work.

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Dinner happened in the same way: work

stopped about 9 p.m., and dinner was served

about 10 p.m. Again, we all sat together at one

long table and ate, drank, laughed, and told

stories till well after midnight.

As the days unfolded I learned more about

how this first-ever traditional kayak symposium

came to be. Several people with different skills

collaborated. Carlos Martinez had built two

skin-on-frame kayaks before and had tools,

and Anibel had built a Yost-designed boat (see

yostwerks.com). Julio is a graphic designer and

physical education instructor at the college;

Leo from Brasil had photo-journalism skills.

Pato quietly worked behind the scenes to see

to the many details. Together, they created

and managed the symposium that would drawover 100 people to its final celebration.

In this way, it reminded me of SSTIKS, so much

positive energy and collaboration, a common

vision and the desire to be inclusive. There was

such a strong sense of community. Everyone

was welcomed and a part of the activities.

Challenges…and Meeting Them

The week was not without its challenges. Julio,

Don, and I were tasked with building steam

boxes for bending the ribs. We got wood

This man would arrive daily with bread, cheese, salami and jam.

The plan for the day was quite clear.

Julio enjoys some quality time with his daughter.



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from a local flooring manufacturer. Finding

something to hold the water and then heat

it to make the steam encouraged us to think

creatively. We found a Mercedes muffler, which

worked nicely, then built a fire under that. Leo,

not wanting to waste a good fire, taught me to

roast cheese on a stick, sort of a cross between

marshmallows and fondue.

There were other challenges that week, some

from learning a culture new to me, some from

my budding Spanish skills, and some from not

having the tools and extravagantly equipped

hardware stores we take for granted in the

United States. Our South American friends

compensate with creative and surprising

problem-solving skills, have an ability to adapt

to almost anything, and communicate in avariety of languages.

That same flooring manufacturer invited Don,

Rony, and Carlos Martinez to use his shop

and equipment after hours to cut the paddle

blanks. We would go pick through his pile of

wood to find the best pieces, then lay out and

mark them according to each student’s dimen-

sions. Then, the shop owner and Don would

use the giant planer and band saw to cut the

blanks. Although neither of them spoke the

Carlos, Don and Rony hard at work in the woodshop.

Paddle carving.

Happy paddle carvers.



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other’s language, they shared the common un-

derstanding of a wood shop. Later, we would

load it all onto Rony’s Land Rover and drive the

five miles back to the park where the carving

class was held.

It is expensive to import things to Argentina.

For example, a $400 Werner paddle would cost

$1200 there due to import tax. So kayaking is

not widely available. But skin boats, plywood

boats, and Greenland paddles are of interest because they are affordable and the materials are accessible for people

to build their own kayaks that fit properly.

There were enough kayaks that weekend to share—plastic, fiberglass, and skin-on-frame. On Saturday and Sunday

people came to observe rolling and ropes demonstrations, try out a kayak, simply visit, and, of course, enjoy a meal

together. All day the multitalented man in the white truck tended a side of beef pitched over a large fire to cook

slowly. To pass the time while the beef cooked, he played guitar and sang. People joined in the singing, and children

danced.

The final night of the symposium one long table stretched to seat over 100 people. It was important that we all sat

together. A large wok held an enormous amount of paella, a rice and chicken dish. Following dinner, Rony read a

proclamation from the Mayor, honoring the

event and its organizers. Then Dubside was to

show a film he’d taken of the National Games

in Greenland. Technical difficulties erupted:

the projector failed. Another challenge and

another problem solved in a creative way. A

chair was placed on top of a table. Someone’s

laptop with a 13 inch screen set on top of the

chair. More than 100 people crowded intently

The hard work paid off.

The classroom.



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around that laptop to watch Dubside’s film. Music, singing, and picture-taking followed and continued long into the

night.

I felt so warmly welcomed, instantly a part of them, and grateful for the opportunity afforded me to participate. The

week ended predictably too soon. Our goodbyes were said with hugs, hasta luegos, and many, many photos taken

together.

Postscript

Since the symposium I have gained a dozen or so amigos on Facebook. Carlos Martinez is organizing an ACA club

in Argentina and has taught three paddle-carving classes. Julio is making and marketing a new line of PFDs and

tow belts, still hoping to entice some builders to help him build a small fleet of wood kayaks for his students. Leo is

in the planning stages of hosting a symposium in Brasil. This spring there are two kayak symposiums scheduled in

Chile. And I am hopeful that we will one day invite our South American friends to our qajaq events.

Biography

Joanne Barta is a kayaker based in Milwaukie, Oregon, and loves paddling in new places. She is an organizer for

the South Sound Traditional Inuit Kayak Symposium (SSTIKS, Washington State in June). She is a Positive Behavior

Support Coach for Portland Public Schools, and she teaches kayaking for the Oregon Ocean Paddling Society andPortland Kayak Company.



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Deconstructing Greenland Kayaks, Part III:

The Mighty Keelson—Results of Destructive Testing

By Ralph C. Young

The basic premise of the “mighty keelson” (2013 Masik ) was that the diminutive keelson on a West Greenland kayakcontributes significant strength to the kayak frame. The keelson and ribs account for approximately 20% of the total

mass of a kayak frame, yet my analysis suggested that they contributed approximately 50% of the strength of the

frame. The method of attaching the keelson to the gunwales at the bow and stern strongly suggests that the Inuit were

well aware of the forces imposed on the keelson and engineered solutions to handle the loads. Analysis and theory are

one thing, but facts are facts, so I built two identical kayak frames, one with ribs and a keelson, and one without, and

destructively tested both frames by loading the middle with sandbags while supporting either end. The testing took

place at the Delmarva Paddler’s Retreat in October 2013.

Figure 1. Test methodology.

The frames were tested by placing 50 lb (23 kg) sandbags directly on top of the cockpit. We measured the deflection of

the frame after each sandbag was placed on the frame until the frame collapsed.

Kayak Frame Details

The kayak frames were built to the specifications, dimensions, and assembly details outlined in H.C. Petersen’s Instruc-

tion in Kayak Building, using the straight gunwale style. I chose this design because Petersen provides detailed dimen-

sions for all the frame members, as well as detailed instructions on assembling the frame. Following Petersen’s direc-

tions, you can use commercially available lumber and traditional building methods to construct a replica of a mid-20th

century West Greenland Kayak rooted in traditional design.

For lumber I purchased four 16’ by 10’ boards of Southern pine from a local sawmill. The wood truly was run of the

mill—coarse grained and full of knots. I bought the wood green, air dried it, and planed it down to the thicknesses

specified by Petersen. I used local Southern pine because it was cheap and it represented a worst-case scenario from a

kayak-building perspective. Between the knots; the rapid-growth, wide-spaced grain; and the erratic grain patterns, I

really don’t think you could choose a worse wood to build a kayak from. There is no doubt in my mind that the slower

growth spruce and fir that drifted through the Arctic Ocean and ended up on the west coast of Greenland was far

superior to the wood used in these frames.



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Figure 2. Completed frames ready for testing.

Figure 3. Not the best wood for building kayaks.

Figure 4. Deck with 200 pounds (91 kg) of sandbags. I cannot explain the green checkerboard; you’ll have to ask Jules.



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Figure 5. Full frame with 550 pounds (250 kg) of sandbags.

Test Results The upper deck structure without a keelson held 300 lb (136 kg) with a deflection of 5” in (12.7 cm) without failing. It

failed when the next sandbag was added. There were numerous failure points on the frame, including both gunwales

aft of the cockpit, a pegged connection between the back cross beam and a longitudinal deck reinforcement, a for-

ward cross brace, and almost all the amidships cross-brace tenons. None of the lashings failed, nor did any components

on the bow and stern. Surprisingly enough the frame did not fail at one of the knots. Figure 5 illustrates where the

failures occurred.

Figure 6. Failure points on the upper deck.

The full deck with keelson supported 550 lb (250 kg) with a deflection of 3” (7.6 cm) without failing, and failed with the

next sandbag. The failure points were at the keelson amidships, as well as both gunwales amidships. No lashings, pegs,

or tenons failed, although one section of the gunwale was torn away by a cross-beam lashing (the lashing was stronger

than the wood). Gunwale failure did occur at a knot location.

Figure 7. Failure points on the full deck.



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Table 1. Frame test results.

As measured by this test, the partial frame without a keelson contributed 55% of the strength of the frame with a keel-

son (300 lb/500 lb); accordingly, the keelson contributes 45% of the strength of the full structure under this test meth-

od. The keelson also stiffens the frame significantly; total sag was limited to 3” before failure, whereas the upper deck

sagged 5” under significantly lower loads. The total frame strength-to-weight ratio improved by 40% with the addition

of a keelson. In summary, adding a keelson to the frame increases the weight of the frame by 8 pounds (3.6 kg) while

significantly stiffening the structure and almost doubling the load-carrying capability.

Failure Analysis

Figure 8. Upper deck after test. There are three discrete failure mechanisms in this picture: the starboard gunwale failed, the pegged connection between the cross brace and the longitudinal reinforcement failed, and the tenon on the cross brace

failed. The exact sequence of failure is not known.

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Figure 9. The starboard gunwale (from theunderside) upper deck after test.

Note that the gunwale failure occurred at amortise location.

Figure 10. Broken cross brace on upper deckstructure. Note that the wood failed parallel

with the grain and that the lashing did not fail.The tenon also failed.

Figure 11. Port-side gunwale failure(viewed from below).

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The component failures suggest that the primary failure mechanism was the vertical bending moments applied to the

gunwales. The gunwale failures ran diagonally, consistent with compressive forces applied on the top of the gunwale

and tensile forces on the bottom of the gunwale. The gunwale failures occurred at mortise locations. The tenon and

cross-brace failures support vertical bending as the primary failure mechanism—the gunwales bowing out would not

break a tenon; they would have just pulled out of the mortises.

The failure mechanisms on the full frame suggest that the gunwales failed more from the lateral bending forces of the

gunwales bowing out than from vertical forces of bending down. This makes sense when you consider that the total

deflection was considerably less (because the keelson was contributing strength to the frame). The flattened ribs and

the torn-away section of gunwale support the theory that the forces on the upper deck structure were largely lateral.

Figure 14 is a picture taken at the moment of failure, which collaborates the theory that the gunwales were experienc-

ing considerable lateral forces.

1 2

Figure 13. Full frame after failure. Note thegrain run-out on the keelson at the failure

point and the wood that pulled away fromthe port gunwale at the point where the cross

beam was lashed to the gunwale. Also notehow flat the ribs are immediately after failure.My theory is that the gunwales were bowingout as the keelson was being pulled up, caus-

ing the ribs to flatten out, and the wood to pullaway from the gunwale, ultimately causing the

gunwales themselves to fail.

Figure 12. Full frame failure. Note that both thestarboard and port-side gunwales failed at acombined mortise and rib location, and the

gunwale failure mode is different than the par-tial deck test: these gunwales appear to havefailed from lateral bending, not vertical bend-

ing. Also note that neither the pegged connec-

tions nor the tenons failed in the full deck test.

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Figure 14. Frame at the point of failure. Note how far the gunwales have spread,indicating that there are substantial lateral forces in play.

Figure 15. Method of attaching keelson to the gunwales to prevent the keelson from pulling away under tension.

Neither end failed.

Although this was a test of kayak frames, not skinned kayaks, the failure mechanisms should be reviewed within the

context of a fully skinned kayak. A tight skin will serve to prevent the gunwales from bowing out, and because the skin

acts on the entire length and width of the gunwale, that additional strength would be significant. I am not sure what

effect a tight skin will have on the keelson and ribs; it is possible that instead of the gunwales bowing out the keelson

would be drawn up. Insofar as the primary failure mechanism was the gunwales bowing out, my guess is that if the

same test was performed with skinned kayaks, the strength of the kayak would be greater and the difference in load-

carrying capability would be even greater.



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Lessons Learned for Skin-on-Frame Builders

1. Love the lashings. Using the commercially available wax coated nylon artificial sinew, not one of the lashings failed.

In fact, the wood failed, and the lashing didn’t fail.

2. Under heavy loads the gunwales will bow outward. If you don’t lash the cross beams to the gunwales (or use pegs),

you are relying solely on the skin to keep the frame intact under heavy loads. I strongly recommend that every other

cross beam be lashed to the gunwales as specified by Petersen.

3. A strong frame can be built using clearly inferior wood. Superior wood will result in an even stronger frame. Try toavoid knots at the amidships location or where the gunwales bend sharply to form the bow or stern.

4. Do not weaken the gunwales by locating a rib mortise in same the place as a cross-beam mortise (see Figure 16).

Minimize the size of the mortises, and consider mortises that do not fully penetrate the gunwale as a means of preserv-

ing gunwale strength.

5. The keelson is under a lot of tension. Make sure that the two ends of the keelson are firmly secured to the gunwales

using the methods described by Petersen, if for no other reason than to limit sag. Look for grain run-out in the keelson.

6. Pay attention to the grain of the wood. For example, the forward cross braces are raised to allow legs and knees

to fit in the kayak. The preferred method of building these braces is to use a piece of wood that already conforms to

the desired shape (like from a stump or bent limb). Another method commonly used is to create a bent laminate. My

method was to cut the brace from a wider board—ignoring the grain direction—and it failed (see Figure 17).

Conclusions

A keelson significantly strengthens and stiffens the kayak frame. If you are designing to a specific hull strength you can

achieve the desired strength with a lighter frame by using a keelson. If you are designing to a specific hull weight, you

can build a significantly stronger frame by using a keelson. To realize the additional strength and stiffness, it is impor-

tant to properly secure the two ends of the keelson.

From an engineering perspective, the keelson is an excellent example of an engineered solution to a critical problem.

Figure 16. Mortise do’s and don’ts. If you locate a cross-brace mortise inthe same place as a rib mortise, you reduce the cross sectional area of

the gunwale and weaken it.

Figure 17. Cross beam do’s and don’ts. Bentwood or laminate cross braces are stronger

than straight-grained wood cut from a widerboard.



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In my mind, the testing confirms that the Inuit kayak builders understood the basics of structural engineering and

strength of materials. Knowing that the keelson would be subjected to significant tensile forces, they sized the keelson

to withstand those forces and designed methods to secure either end of the keelson.

Musings

This whole episode started when a colleague criticized my kayak’s hull design, stating that by putting most of the mass

of the kayak at or above the waterline, the Inuit created an inherently unstable vessel—or at a minimum increased the

instability of a marginally stable vessel. I spun off on a tangent trying to prove that the design was solid by focusing on

the unique aspects of the keelson (or “not-a-keel” as my colleague called it). What I believed at the time was that the

upper deck was weak if exposed to bending forces, and the keelson was needed to prevent the kayak from failing in

heavy seas or sagging under normal conditions.

What this test indicates is that the deck is plenty strong on its own accord, probably stronger than it has to be. If you

load one of these kayaks up with 300 pounds in the water it won’t break; it will sink intact and rest peacefully on the

bottom. Although I believe that I have proven that the keelson is in fact a wonderfully engineered component worthyof our admiration for its strength and simplicity, I have really not addressed the issue of distribution of mass above the

waterline. At minimum, the West Greenland Inuit could have reduced the mass of the upper deck without sacrificing

any strength, in a manner similar to that of the baidarka or the Mackenzie River Kayaks (Figure 17). In the words of Nick

Schade, “If it breaks, make it bigger; if it doesn’t break, make it lighter; if it slides apart, tie it together; if it slides togeth-

er, block it apart.”

Figure 18. Mackenzie River kayak frame. Note that the upper deck components are significantly smaller than those in theWest Greenland kayak and that there are multiple longitudinal stringers. In theory, this design will result in a lighter weight

and higher strength-to-weight ratio.

So now the question is why the deck of a West Greenland kayak is so heavy (and so strong). If the West Greenland Inuit

were as smart as I think they were, or if they simply worked to Nick Schade’s rules, they should have figured out that

they could make their kayaks lighter and more stable without making them weaker. Ben Fuller comments that the

West Greenland kayak is the oldest and least sophisticated of the Artic kayaks; that is certainly one plausible explana-

tion. Tom Milani speculates that the type of water the kayaks were paddled in has an influence on the design, noting

that Canadian and Alaskan kayaks carried their prey (and other cargo) inside the vessel. He also questions if the frame



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is designed with rolling in mind. There may be may be sound logic behind the design. Strength is only one aspect of

kayak design; durability and resilience may be equally important. And as much as I tout space-frame structures for their

strength-to-weight ratios, they are not the most durable structures. If one element is damaged or fails, the loads on

adjacent elements increase, and the failures multiply rapidly. In the full deck test everything was fine one minute, and

everything failed the next minute.

The answer is probably a combination of the above. The West Greenland kayak was primarily a hunting vessel, capsizesand rolling are inevitable, and West Greenland is fraught with dangers that are not as prevalent in the more western

areas of the Arctic. Getting tossed up against the rocks or an iceberg can break a keelson, and such a calamity can have

two outcomes. Based on my test results, a broken keelson on a West Greenland kayak will result in a compromised but

still intact kayak. It may sag a little more but the deck is strong enough to preserve the structure and allow the occu-

pant to remain in the kayak. If the deck structure were more like a true space-frame structure, with smaller cross braces

and longitudinal stringers, loss of the keelson may be catastrophic. The heavy deck structure of the West Greenland

kayak may be a feature designed to protect the occupant from harm in the event of damage to the vessel. True, it

results in a vessel that is heavier and more prone to capsize, but a capsize can be recovered from, whereas a broken

frame will almost certainly result in death of the occupant.

It may be a coincidence that the kayaks of the western Arctic that have lighter decks come from regions characterized

by broad shallow coastlines absent of icebergs. Rasmussen comments that the use of kayaks in the western Artic are

more limited to rivers and bays. It may also be a coincidence that the Inuit from the western Arctic did not develop roll-

ing and capsize recovery methods like West Greenland Inuit. Somehow I don’t think so.

Observations and Speculations

I saw this picture in on page 41 of Kaj-Birket-Smith’s book Eskimo.

Figure 19. “Primitive” E skimo sledge from the Caribou Eskimo.

The primitive Eskimo sled is very similar to the deck of the West Greenland (and many other) kayak frames. The side

rails are long and thin, the cross braces are short and thick, the cross braces are spaced closely together, the middle of

the side rails is taller than the ends, and there is a slight amount of rocker in the rails (the ends of the rails are slightly

higher than the midsection). If you pull the two ends of the sled rails together you have the deck of a kayak. If we as-

sume that the dog sled came first, we can make an argument that the kayak is a direct descendent of the dog sled. I’m

sure that numerous other researchers have made the same observation, but I couldn’t find a point by point discussion

of the similarities between sled and kayak, so here goes. My favorite observation is that the kayak and the dog sled are



22/93

both watercraft. The water that supports a dog sled is harder than the water that supports a kayak, but snow, ice, and

water are just labels for the different physical states of H2O, and within the context of survival in the Arctic, the Inuit

had to understand that water is still water regardless of its state.

My second observation is that both vessels are designed to withstand significant bending forces; the sled had to with-

stand the forces associated with crossing a crevasse or break in the ice (Figure 20).

Figure 20. Primitive sled crossing a break in the ice. Note the bending forces imposed on the structure are very similar to theforces on a kayak between two waves.

The similarities between sled and kayak don’t end there; more advanced sleds take on the characteristics of space-

frame structures (Figure 21).

Figure 21. Advanced Inuit sled frame. Note the space-frame structure details.

As previously mentioned, both vessels incorporate rocker, a slight bow in the bottom of the structure. It is well known

in the modern kayaking community that adding rocker to a kayak frame improves the maneuverability of the kayak.

With respect to rocker on dog sleds, consider this passage from Birket-Smith, page 81, when describing sleds of the

Caribou Eskimos: “Maneuvering with these long sledges might seem difficult, but in reality only a short length of the

runners rests upon the snow, as their undersides taper up the front and back.” Just as rocker reduces the amount of the

sled rail that is in contact with the ice, rocker reduces the amount of hull that is in contact with the water, in both casesimproving maneuverability.

Within the context of survival in the Arctic, you can imagine a close relationship between kayaks and dog sleds. They

are the only vehicles available to carry hunters, weapons, and prey; they are both essential for survival; they are both

made of a material that is in short supply; and they are both designed to withstand bending moments. This relation-

ship is documented in Eugene Arima’s book Inuit Kayaks in Canada: A review of Historical Records and Construction,

from page 101:



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The sled and kayak not only use identical materials and similar methods of construction, but their critical dimensions

are not that dissimilar. Table 2 is a comparison of the dimensions of dog sleds described by Therkel Mathiassen in Mate-

rial Culture of the Igluik Eskimos, one of the Reports of the Fifth Thule Expedition of Knud Rasmussen.

Table 2. Comparison of various sleds with Petersen’s kayak.

The exact relationship between sled and kayak is probably not knowable, but we can speculate. From a resource per-

spective it makes sense to retain common features of the two vessels. If wood is plentiful, you build one sled and one

kayak. If wood is scarce, you make do with a single vessel and modify it to meet the demands of the seasons. And even

if wood is plentiful it makes sense to retain the flexibility and common methods of construction, for no one knows

what tomorrow will bring. Insofar as sleds were used primarily in winter and kayaks were used primarily in summer,

such a conversion can be made without sacrificing survival chances.

And so I propose that one possible explanation for the similarities between kayaks and sleds is that the Inuit needed

to maintain the ability to convert the craft from one form to another. If a hunter has a kayak and a sled, and somethingdisastrous happens to the sled, he doesn’t have to start from scratch to build a new one. If his kayak is smashed on the

rocks, and he has the good fortune to survive, he can borrow parts from the sled to build another kayak. Considering

the scarcity of wood and the amount of labor necessary to shape a log into a gunwale or a skid, we should not discount

the importance of having a backup plan; if General Motors can share components across multiple platforms, so could

the Inuit.

From a knowledge perspective it also makes sense to retain common features. The Inuit knew how strong sled frames

Forested country was also visited for fresh timber, sometimes from afar with journeys months long. For ex-

ample, from the Northwest Labrador Peninsula a man might travel several hundred miles south to the trees in

winter and make a sled to be converted later to a kayak as the summer overtook him on the return trip north.



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were from daily experiences (my little experiment was repeated every time a crevasse was crossed). By building a

kayak frame with the same features, they knew they had a strong frame, with or without a keelson. It also makes sense

to employ common construction means and methods. By using one common set of tools, materials, and methods, the

Inuit make maximum use of minimal resources.

Finally, I am proposing that the kayak is a direct descendent of the sled, and that alone can explain the similarities. I

don’t think the kayak evolved from birch-bark canoes, or dugouts, or inflated whale carcasses.

I think it happened like this:

A group of hunters on dog sleds are pursuing caribou across the tundra, a chase that has gone on for weeks, and

finally they find their prey. Sadly, by now the rivers have thawed, the caribou are on the other side of a river, and our

hunters have no way of crossing.

Hunter #1: “All this time and nothing, nothing to show for it. All that meat, and no way to get it.”

Hunter # 2: “I’m not turning back. We’ve gone too far to turn around with nothing to show for it. If we don’t bring back

meat we will not all survive.”

Hunter # 3: “There is no way we can cross this river, it is too wide, too deep. We will die.”

Hunter # 4, looking at his sled: “It’s too bad these things don’t float like an ice floe, we could just stand on them and

pole our way across.”

Hunters # 1, 2, and 3 stare at Hunter #4. Maybe not right then and maybe not right there, but pretty soon seal floats go

under the sled, a little later ribs and skin get added, and before long the kayak is born.

Peer Review Comments / Ben Fuller

Read this with interest, some comments:

I'd lose the “understood.” These folks did not understand in the sense that engineers understand. All was empirical:

there was no language to describe this. Pretty much the same in all non-mathematical cultures. Design is evolutionary.

On the sizing of the gunwale stringers, you can’t get much smaller given the deck beam and rib sizes and keep uncut

grain runs. You have mortise pockets coming up and the deck beam mortises coming through. So the “working” part

of the gunwale, the run of uncut wood above the deck mortises, below the deck mortises and above the rib mortises,

and on the outboard side of the rib mortises, is much smaller than the total size of the gunwale.

I'm not surprised that the gunwales rotated out to fail. Part of that was in the way the system was loaded. You had

point loading on the gunwales at the points of contact of the platform that supported the bags, and perhaps moreimportant, it looks like the tops of the gunwales were not flat but flared out. If that’s the case, there would be tendency

for the gunwale to rotate out. Might have happened anyway giving the flare to the gunwale.

The skin has to make a huge difference. As soon as you skin one of these things with its tensile strength the frame

strength has to go up by order of magnitude.

So my conclusion is that the gunwale fabrication has more to do with the size of all materials and working them than



25/93

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Contributing toThe Masik

any entrapment issues.

The paper done by a Finnish guy whose name Vernon would remember that talks about

complexity in skin-on-frame construction as well as adaptation to various ecological niches is

worth a look. Arguably, the Eastern end and oldest of the peopling of the arctic has the least

sophisticated construction.

Author’s Response

I pondered how to support the sandbags a great deal. I wanted to place them in the cockpit to

simulate the weight of the paddler, but the Inuit also carried loads on the deck beams. I finally

settled on the plywood on top of the frame because that was the simplest way to do it, and

Ben is right, the pressure of the plywood on the gunwales no doubt caused the gunwales to

bow out more than if all of the weight was placed in the cockpit. The method of supporting

the weight was identical for both the full frame and the partial frames, yet the failure mecha-

nisms were different, so I’m sticking to my position that the keelson is a critical structuralmember of a skin-on-frame kayak.

With regard to empirical knowledge, I agree that the Inuit did not understand this stuff in the

same sense that engineers do. Their knowledge was based on experiences, both good and

bad, experimentation, observation, analysis, comparisons, real-world learning. All humans

benefit from experiential learning, and somehow we managed to survive for hundreds of

thousands of years before language, classroom education, and engineering were developed.

In our current condition we employ both empirical knowledge and knowledge obtained

through less experiential methods to navigate our way through life. Without getting overly

philosophical, it seems we should not underestimate the significance of empirical knowledge.

Video link: https://vimeo.com/83906123.



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Deconstructing West Greenland Kayaks Part IV:

Hull Design Part One: Form Follows Function

By Ralph C. Young

Copyright 2014

Hull design is the most complicated aspect of naval architecture. Achieving a comprehensive understanding of hull

design and fluid dynamics may be the engineering equivalent to Buddhist enlightenment: many speak of it, but few

achieve it. Although we have a pretty good idea of what happens, and why, the underlying physics of a vessel traveling

through water still overwhelms most engineers, yet somehow the Inuit designed one of the most sophisticated hull

designs without the benefit of our ship-building history or our understanding of the physical world. As discussed in

prior articles, knowledge can consist of an in-depth understanding of a subject obtained through practice and experi-

ence (empirical), or it can be based on education and the application of scientific or mathematic rules. In some ways,

hull design is not that complicated; man has been building boats for tens of thousands of years and has pretty much

figured out what works and what doesn’t work. On the other hand, man is currently spending many millions of dollars

every year on complex modeling software and tow tanks trying to better understand hydrodynamics and hull design.

The question this article addresses is how empirical knowledge alone can produce a vessel as sophisticated as the

Greenland kayak.

Just as boat design can be empirical or scientific, so too is communication. Accordingly I have written this article in twolanguages, Plain English and Engineering Terminology.

Purpose

This article will deconstruct the various aspects of the West Greenland kayak hull design for the purpose of under-

standing the design features and will present a theory that explains how the Inuit were able to design sophisticated

watercraft solely using empirical knowledge.

Basics

Hull design determines stability, speed, seaworthiness, efficiency, stealth, control, etc. David Zimmerly makes the point

in his 1983 article “Form Followed Function and the Function Was Hunting”:

It is the pervading law of all things organic and inorganic, of all things physical and metaphysical, of all things

human and all things superhuman, of all true manifestations of the head, of the heart, of the soul, that the life is

recognizable in its expression, that form ever follows function. This is the law.

—Louis Sullivan.

Sea mammal hunting boats depended on stealth rather than outright speed for success, because a frightened

seal will dive and be gone in an instant. The boats had to be seaworthy, too; the wind swept Arctic coasts de-

manded no less. Finally, such boats had to carry home captured game, sometimes over considerable distances.



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The Inuit needed a highly efficient watercraft to cover long distances in search of their prey; they need a stealthy vessel

to approach their prey within killing distance, and they needed speed to recover the prey before it sank. Stealth has at

least two components, visibility and sound. We know that the Inuit understood the need for a silence from C. E. Whit-

taker’s account of a whale hunt (Inuit Kayaks in Canada: A Review of Historical Records and Construction, E.Y. Arima, page

10): “Dead silence prevailed among the hunters, as they believe the whale has very keen hearing. In the settlement

even, two miles away, wood-cutting, or digging, or other noisy work was forbidden, lest the whales be frightened.”

From the pictures of kayaks with white screens across the front deck, we also know that the Inuit knew it was impor-

tant to not be seen. So if we subscribe to the theory that form follows function, we can use that context in the decon-

struction of the West Greenland Kayak: all aspects of the kayak’s hull design are defined by the functions that the kayak

must perform.

Discussion in Plain English

Stealth means a kayak travels through the water quietly and with minimal visibility. Efficiency means maximizing the

distance you can travel with your physical effort. The hunter’s mission was to locate, kill, and retrieve his prey in a single journey. The more distance you can cover the better your chances of encountering prey; double the distance you can

travel and you quadruple the area you can cover (see Figure 1). Stealth means silence and low visibility. Sound travels

almost five times faster in water than it does in air, and marine mammals have very good underwater hearing. Their

underwater hearing is significantly better than their above-water eyesight, so silence is probably more important than

low visibility. Whoever has the quietest, least visible, and most efficient kayak has the highest success rate when hunt-

ing. He will succeed when others don’t, and his hull design will be copied by less successful hunters.

I am proposing a very simple explanation for a very complex hull de-

sign: the West Greenland kayak is designed specifically to minimize

the amount and type of hull noise generated underway. Noise coming

from a kayak will warn seals and other marine mammals that a hunter

is approaching. Sound travels really well in water, and seals have

really good hearing when underwater. My theory is that every Inuit

kayak builder was conscious of the need to build a silent vessel, and

that through experimentation and observation they optimized their

designs to minimize acoustic emissions.

Figure 1. Double the distance that you can travel and you quadruple thearea within your hunting range.



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There is some synergy here—noise is a byproduct of an inefficient design. Water that travels smoothly and silently past

a hull is the ideal, and friction is minimal. When smooth flow is interrupted, water moves in a turbulent fashion; fric-

tion increases, and so does noise. The theory is basically that the quietest hull will be the most efficient hull; the Inuit

tinkered with their kayaks until they it couldn’t be perfected any further, and by doing so invented one of the most

efficient hull designs in our maritime history.

Discussion Using Engineering Terminology

A kayak is a displacement watercraft. A fully loaded kayak that weighs 192 pounds (87.2 kg) displaces 3 cubic feet (.085

cubic meters) of saltwater. If you move that kayak one boat length you have to move 3 cubic feet of water out of the

way, and 3 cubic feet of water has to flow into the void left by the kayak. If you want to cover 4 miles in 1 hour, you

need to move at least 52 cubic feet of water out of the way every minute. The amount of work it takes to move that

water is a function of the hull design. The amount of noise that moving all that water makes is a function of hull design.

An inefficient hull design will require a lot of work to move the water and will make a lot of noise. An efficient hull de-

sign will require considerably less work to move the same amount of water and will make less noise. Efficiently moving

water is paramount, and the key to efficiency is to minimize the rate of change in velocity of the displaced water mol-ecules. A long, pointy, and narrow boat displaces water at a slower rate than a short, fat kayak with the same displace-

ment. Put simply, the water is displaced more gradually over the length of the vessel, and by doing so it is possible to

maintain laminar flow of the fluid.

In addition to the work required to displace water, we also have to work to overcome the friction of a boat moving

through water. We know that the most efficient means of moving water is to create and maintain laminar fluid motion.

In the case of a kayak moving through water, there will be a layer of water molecules that adhere through friction to

the hull, and that through friction between water molecules more and more molecules will be dragged along with

them. Of course, there is slip between the molecules, but as long as the molecules move smoothly friction, or drag, is

minimized. Try to move those molecules too quickly in any direction and the smooth boundary layers break down and

turbulent flow results, and with turbulent flow drag increases. Figure 2 illustrates the difference between laminar and

turbulent flow.

Figure 2. Laminar flow (top) versus turbulent flow (bottom).



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As seen in plan view, the hull of the West Greenland Kayak is tapered from bow to stern. The hull is either getting wider

or getting narrower for the entire length of the vessel. From a water-displacement perspective, the displacement of

water away from the hull takes place over the entire front half of the boat, and the return of water toward the vessel

takes place over the entire rear half of the boat. Gently displacing water over the full length of the kayak not only helps

to maintain laminar flow, but is also reduces the amplitudes of the bow wave and the stern trough. Not only is the

kayak tapered as seen in a plan view, but is also tapered in the side view and the forward and aft cross sections (Figure

3). The displacement of water takes place slowly and gradually over a long length of the hull.

Figure 3. The bow of the kayak is tapered in allthree dimensions, resulting in gradual, efficient,

and silent displacement of water.

Plain English

Now this all sounds very complicated but it re-

ally is not; it’s common sense. You don’t need

an engineering degree to understand that

water moving slowly and smoothly makes

less noise than water moving quickly and

chaotically. You don’t need a degree in marine

biology to figure out that seals, whales, and

other marine mammals have really good hear-

ing when underwater. And you don’t need a

degree in naval architecture to design a hull that moves smoothly through the water. But you do have to be smart, you

do have to be observant, and you do have to be resourceful. You have to make sure that the surface of your kayak issmooth, and you have to minimize the rate at which the hull changes shape. Seal skin was fine-tuned through evolu-

tion to move smoothly and quietly through the water, solving problem # 1. Making the kayak long and narrow solves

problem #2. So how did the Inuit do it? The sea was their laboratory, their senses were their instruments, their brains

were their computers, and their experiences guided them. Get it right, you build an efficient and quiet kayak and your

family survives. Get it wrong and they won’t. This isn’t trial and error; it is focused problem-solving using empirical

knowledge when survival is on the line.

The Theory: Form Follows Function

My theory is that every aspect of the Greenland kayak design was dictated by functional requirements, and by analyz-

ing the functional requirements we can gain insights into the designs. In military speak you first define the mission, and

then use the mission statement to define the functional requirements.

The mission statement: Safely and efficiently transport the hunter and his weapons to his prey through frigid waters

under a wide variety of sea conditions, permit the hunter to approach and kill his prey in a stealthy manner, and safely

transport the hunter and his prey home again.



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The following features are required to meet the functional requirements:

1. The kayak must protect the occupant from life-threatening conditions and events.

2. The kayak must be seaworthy

3. The kayak must be efficient

4. The kayak must be stealthy

The trick is meeting all the functional requirements because they compete with one another, and some of the require-

ments are more important than others. For example, a kayak can be made safer by making it big (high volume) and

wide, but it won’t be very efficient, if the wind is blowing it won’t be very seaworthy, and the seals will see it coming a

mile away. My take on the priority of the functions is as follows:

Lest you think I am just making this stuff up, the U.S. Navy followed the exact same logic in World Wars I and II when

designing submarine chasers. They needed stealth to sneak up on the enemy, efficiency determined how far they

could travel without refueling, they got thrown around in heavy seas, and there was precious little armor on them be-

cause that added weight and reduced efficiency. The parallels don’t end there—a submarine could not outrun a sub

chaser, so their primary defense mechanism was diving!

Stealth

The two primary elements of stealth are noise and visibility. If the kayak makes no noise and presents a minimal silhou-

ette, it is stealthy. Minimizing buoyancy and freeboard minimizes the silhouette; creating hull and paddle designs that

minimize disturbance of the water minimizes the acoustic emissions of the kayak. Smooth laminar flow of water around

the kayak and the paddle is the key to silence. Silent paddling depends not only on the size and shape of the paddle,

but also the skill of the paddler.

– Stealth is the highest priority. If the Inuit hunter could not get close to a seal, whale, or walrus, he could

not kill it, and without the ability to kill seals the West Greenland Inuit would face extinction.

– Efficiency is the second highest priority. The more efficient the kayak is, the farther the hunter can

travel in a given time period (or with a given level of effort). The farther a hunter can travel, the more areahe can cover, which improves the probability of finding and killing prey. The relationship between travel

distance and hunting area is not linear; if you double the distance a hunter can travel, the effective hunt-

ing area increases by a factor of four.

– Seaworthiness is the third priority. A vessel with poor seaworthiness could still put out to sea on a calm

day. It’s still important to be seaworthy so you can maximize the number of days you can hunt, but it is not

as important as stealth and efficiency.

– Protecting the occupant receives the lowest priority. As we all know, a Greenland kayak is prone to

capsize, so we learn how to balance and brace to prevent capsizes, we learn how to roll to when the brace

doesn’t work, and we wear protective clothing so we don’t freeze to death if we do capsize. The Inuit

accepted the risk of an unstable kayak and implemented paddling and clothing methods to mitigate the

risks.



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Efficiency

Again, a hull design that minimizes disturbance of water should have high-efficiency values, and smooth laminar flow

of water around the hull is important. Inefficiency can be measured as drag, defined as resistance to the motion of a

body through a fluid. This gets really complicated, as drag is a function of the submerged surface area (also known

as the wetted surface area), the shape of the hull, and the smoothness of the hull surfaces. The wetted surface area is

mainly a function of the displacement of the kayak, although different kayak designs with the same displacement have

slightly different values for wetted surface areas. You probably can’t get much better than seal skins for your surface, sohull shape becomes the single most important factor in efficiency.

Seaworthy

It’s difficult to characterize any vessel that is prone to capsizing as being seaworthy. Nonetheless, there are degrees of

seaworthiness even in vessels that are tippy. Just because the Greenland kayak has lateral instability issues (like cap-

sizing) doesn’t mean that it can’t take a 2-meter wave head on with minimal risk to the occupant. Because of the hull

design, the pointy bow and stern, and the distribution of buoyancy, these kayaks are quite seaworthy from a longitudi-

nal perspective. The low profile minimizes the effects of high winds. We just have lateral stability issues that are com-pensated for with skill and training.

Protection

The kayak does a very good job protecting the lower half of your body from the elements; protective clothing is

required to protect the upper half. Although the tuilik may not technically qualify as part of the vessel, the two do go

hand and hand.

The Proof

My contention is that the West Greenland kayak hull design is one of the most sophisticated vessel designs from a

stealth (and coincidentally efficiency) perspective. Proving this premise is going to be difficult—how do you measure

stealth? The one aspect of hull design that is quantifiable is efficiency. We can measure the resistance to flow for vari-

ous hull designs and declare the vessel with the lowest drag the winner. In theory, this can be done with the computer

models developed for just such purposes, but models rely on assumptions and estimates, assumptions and estimates

can be manipulated, and the results can always be disputed. To be credible, I believe the proof must be physical and

repeatable. Accordingly, I have devised the following test:

1. I will build several scale models of noteworthy seagoing vessels, including a West Greenland Kayak, a

submarine chaser, an America’s Cup Sailboat, a speedboat, and maybe some other hull designs if I have

the time. Each model will be the same length overall, each model will be proportional to its original de-

sign, and all models will have the exact same displacement.

2. At the next Delmarva Paddler’s Retreat, we will drag each model through a pool using a constant force.

Figure 4 illustrates how the constant force will be achieved. We will record the time it takes each model to

travel the distance of the pool. We will run several heats to confirm repeatability of the test results.



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Figure 4. Constant force tow mechanism.

Hull Speed as it Applies to West Greenland Kayaks

A kayak is a displacement vessel, and as it moves forward it forces water out of the way. It takes energy to move water,your energy. When you paddle your kayak much of the effort goes toward simply moving water out of the way so your

kayak can occupy that space. The faster you go, the more water you have to move, the harder you have to work. As a

kayak moves through the water, water molecules are being moved in many directions, but the two main movements

are that water that is in front of the kayak is moved forward and to the sides to make room for the kayak, and water

that is alongside and behind the kayak moves into the void left behind the kayak.

Water is not compressible, so those molecules that are being moved have to go somewhere. They can’t go down

because there is an incompressible column of water below them. They can go sideways, but only if they push another

molecule out of the way. The water molecules that are at rest want to stay at rest, leaving the moving molecules no

choice but to go up. Air is compressible and will allow the water to move up. This is the path of least resistance, so

water piles up. A bow wave is nothing more than a pile of water molecules that has been moved up higher than the

surrounding molecules. We all know that physics will not allow those molecules to stand up indefinitely—gravity will

bring them down to mix with their brethren—so the wave will move more or less sideways until all the displaced water

is back to its comfortable equilibrium state at sea level.


3. The hull design with the lowest drag will be the fastest, all other factors being equal.

4. At the same time, we will attempt to quantify the acoustic emissions generated by the hull by placing

a hydrophone 1 meter under the path of the hull and recording and characterizing the sound made by the

hull passing through the water.

5. If the West Greenland model scores at or near the top of the rankings, and if the kayak frame has one of

the lowest acoustic emission levels, I will argue that the Inuit achieved an efficient hull design by making a

quiet vessel.


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At the back end of the kayak a stern trough is generated by the kayak exiting a space it used to occupy. Water flows

into the void left behind the kayak. The bow wave is an accumulation of water higher than the waterline at rest, the

stern trough is a depression below the waterline. The faster you go the higher the water at the bow, and lower the wa-

ter is at the stern. If you think of the bow wave as an area of high-pressure water in front of you and the stern trough as

an area of lower pressure water behind you, you can visualize the forces that work against you as you try to go faster. If

you go fast enough the bow wave start to interact with the stern wake causing the kayak to “squat” in the water. John

Heath described the phenomena in his article “Climbing a Liquid Hill.” Naval architects describe this as the hull speed,and a gentleman named Froude was able to mathematically describe the phenomena and was aptly rewarded with a

number being named after him. Figure 5 illustrates a kayak at or near its hull speed; Figure 6 illustrates a kayak travel-

ing faster than its hull speed.

Figure 5. Kayak traveling at or near its hull speed. Note the length of the bow wake is the same as the length of the kayak

as measured at the waterline.

Figure 6. Kayak exceeding its hull speed (exaggerated). Note that the trough associated with the bow wave interacts withthe stern trough to create a depression under the stern. This phenomena is what John Heath referred to as “Climbing aLiquid Hill.”

If you want to learn more about this subject, mix a really strong drink and Google Froude number. However, all you

really need to know is that the longer the length of the vessel, as measured at the waterline, the further the bow wave

has to travel before it interacts with the stern trough, which means you can go faster before experiencing the effects

of the interaction. Once you hit that point where the bow wave interacts with the stern trough, the amount of work

required to go any faster increases dramatically, so hull speed effectively limits the top speed for displacement ves-

sels. Military vessels typically power through hull speed (flank speed) because the mission may depend on it and theycan afford to, but commercial vessels and human-powered vessels typically don’t have the necessary horsepower.

Although length at the waterline is the main factor in hull speed, the shape of the hull affects amount of resistance you

encounter at or near the hull speed. Except that it isn’t that simple.

Just like center of gravity or center of buoyancy is a simplification that engineers create to enable them to understand

much more complicated issues like distributions of mass and buoyancy, the whole concept of Froude numbers and hul

speed is a simplification. The length of the waterline defines the distance that the bow wave has to travel to reach the



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stern wave, but the shape of the hull determines the magnitude of the effects of the hull-speed phenomena. For exam-

ple, let’s look specifically at the phenomena we refer to as a bow wake. Unless you have a vessel with a blunt bow, like

a tanker, it is not a bow wake, it is a hull wake. It may originate at the bow, but so long as the cross-sectional area of the

hull increases, water is being displaced away from the hull, and the shape of the wake is changed. The Greenland Kayak

has a V shape when viewed from above, and a V shape when viewed from the bow. These V shapes result in a gradual

displacement of water, which translates into a long and low bow wave, as opposed to a short, high bow wave typical of

most vessels. As a result, the effects of the interaction between the bow wave and the stern wake are minimized. Theinteraction is still there, but the impact is lessened. The same logic applies to the stern. If the kayak had an abrupt blunt

stern, there would be large and deep depression in the water behind the kayak. Because the Greenland Kayak stern

has a gradually decreasing cross section, water can flow into the void left behind gradually, which results in a small and

shallow depression. There is still an interaction between the bow wave and the stern trough, but the effects of the in-

teraction are minimized. Length of the vessel determines the speed at which the interaction occurs, but the hull shape

affects the magnitude of the interaction.

An interesting design characteristic is that the shape of the bow and stern effectively increase the kayak’s length at

the waterline as speed increases. West Greenland kayaks are characterized by significant rake; a lot of bow and stern

extend out of the water at normal cruising speed. However, at the hull speed the bow wave piling up in front of the

kayak and the stern trough deepening at the stern results in more of the bow and stern being submerged—the length

of the waterline increases. An increase of the length at the waterline increases the wavelength of the bow wave, which

increases the theoretical hull speed. Genius!

Another interesting phenomena goes back to our old friend, distribution of buoyancy. Because there is very little buoy-

ancy in the bow and stern, the influence of the bow wave on the pitch of the kayak is minimized.

In sum, the hydrodynamics of a vessel moving through water are so complicated that research facilities spend mil-

lions on tow tanks just to validate their computer models, and mere mortals don’t have a chance of understanding

the underlying physics or mathematics. The Inuit did, but we can’t. And I believe the reason that we can’t is because

we can’t view the subject holistically—we have to break it down to things we can quantify and characterize and apply

algorithms to. Our knowledge base relies on quantifying things, on computer models, simulations, understanding the

very basic molecular and sub-molecular laws that control motion. But when it comes to hull design, I believe the Inuit

had the edge over Western society because their knowledge was obtained differently—the sea was their laboratory,

their senses were their instruments, their brains (collectively) were their computers, and survival was on the line. In our

Western way of thinking, we fail to look at the continuum (anything that goes through a gradual transition from one

condition to another condition without any abrupt changes) of the hull wave phenomena and attempt to model that.

Instead we simplify things and concentrate on vessel length.

My belief is that the Inuit did understand these complex hull configurations because they were not constrained to

knowledge based on mathematics. Rather than attempt to reduce physical phenomena into mathematical representa-

tions, requiring simplification, they obtained a different kind of knowledge by observing the phenomena and learning



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from each experience. They obtained a holistic understanding of the behavior of vessels and the sea, a knowledge that

was not constrained by an algorithm. Within the simple context of this article, they learned what makes noise, and then

learned how to minimize noise by gently moving water from one location to another, and then used that knowledge to

build the stealthy hunters they needed to survive. Of course, it doesn’t end there; it continues to seaworthiness, stabil-

ity, navigation by day and night, weather, animal behavior, etc. etc. etc.

In the peer review of my articles someone inevitably refers to trial and error as the explanation for how the Inuit wereable to design sophisticated watercraft. If that is your mindset, I can’t change that, but I can ask you to at least allow

them an expanded context: trial, observation, perception, analysis, reflection, discussion, understanding, obtaining

knowledge, sharing the knowledge, transferring knowledge to the next generation, using the knowledge to identify

improvements, implementing the improvements and repeating the process over and over and over forever because in

their world there was no such thing as good enough.

David Heath’s Review Comments and Author’s Responses

HEATH: In your discussion of the requirements for a kayak, I would add the following: 1. The kayak must protect the occupant from life-threatening conditions and events.

2. The kayak must be seaworthy.

3. The kayak must be efficient.

4. The kayak must be stealthy.

5. The builder must be able to build it with minimal effort, from things he can obtain, with minimal effort.

Agree with #5, overlooked that.

HEATH: Mr. Dyson proposes using modern materials for his bidarkas. That tended to drive my father into a frenzy

whenever it came up. He felt that the original materials, if they could be found as good quality wood, etc., were so

close to perfect, that why would one corrupt the design? I think I can see both sides, but I tend to favor my dad’s opin-

ion on that one.

I’m in the middle on that. I understand being a purist, but from what I read the Inuit weren’t. They were more than happy to

incorporate mast hoops for cockpits, nails, iron, or anything else that made their lives easier. So maybe Dyson is just carrying

on the evolutionary change.

HEATH: I would feel more comfortable adding these few words to the following sentence from your text: “The faster

you go, the more water you have to move in each second, the harder you have to work.” It seems to me that any

particular kayak, when moved a certain distance, will require moving pretty much exactly the same amount of water,

regardless of the speed. At least until the speed gets high enough that it splashes the water around.

I don’t know. The faster a car or airplane goes, the more air it moves, as measured as cubic feet per minute. You still displace

32 cubic feet per boat length. If you go one boat length per minute you move 32 cubic feet per minute. If you move 10 boat



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lengths per minute you move 320 cubic feet per minute.

However, all you really need to know is that the longer the length of the vessel, as measured at the waterline, the further the

bow wave has to travel before it interacts with the stern trough, which means you can go faster before experiencing the ef-

fects of the interaction.

HEATH: The previous quote makes me quite uncomfortable. The bow wave is always at the bow; it does not traveltowards the stern at all. If anything the stern is traveling toward the bow wave. I don’t remember ever hearing anyone

talk about this, but at the moment it seems logical that the movement of the water to get out of the way of the boat, is

kind of like ringing a bell. A certain amount of water gets pushed up, and then falls, and then bounces up, and contin-

ues to oscillate for quite some time.

Just when I think I understand something, boom, there it goes. You are absolutely right, the bow or hull wave travels diago-

nally away from the kayak, and the kayak travels into the (wake?) of the wake? Echo? Trough? When you look at pictures of

sailboats traveling at their hull speed you see a periodic wave that has its high point right amidships, with the trough at the

bow and stern. I’ve tried watching kayaks at speed, but the wake is not as pronounced as in my drawings. Maybe the tow tests

will help us visualize the phenomena. Thanks.

HEATH: Therefore, if I am correct, and I think there probably is a much more accurate analogy of this somewhere if you

want to look for it, then the length of time that it takes for the water to fall and then rebound to its maximum height

before falling again, might be quite constant. Depending on the gravitational constant, or something. Like if you drop

a rock in the water and watched the waves move out as the water level where the rock landed goes up and down. And,

if I am correct, then that would make it very logical that the waves get further apart the faster you go. Because you go

further during the unit time that exists between one peak and the next. One oscillation. You might want to see if youcan get a reference that explains that far better than I can, and hopefully that is well proven. My thought is just a guess.

If I have it right, the whole basis for Froude’s number is the relationship between the speed of the wave and the wavelength,

and that is a constant rooted in gravity and the physics of moving water. And I understand what you are saying regarding the

oscillations of the bow waves in the water. However, at speed all the oscillations occur away from the hull of the kayak and

therefore cannot affect the kayak’s speed or efficiency.

HEATH: I certainly agree with your point that if we can minimize the height of the bow wave, that that will minimize the

depths of the trough and the height of the next wave. All of that will minimize the raising of the bow and lowering of

the stern while climbing the Liquid Hill.

I have been researching this subject for the last year, and think that the key factors are as follows: entrance angle of the bow

(in all three dimensions) length-to-width ratio of the vessel, the form of the whole as a whole (that probably only makes sense

to me but I don’t know any other way to say it), and the exit angles of the stern (in all three dimensions).



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HEATH: I have not thought about this next sentence in that manner before: “Because there is very little buoyancy in the

bow and stern, the influence of the bow wake on the pitch of the kayak is minimized.”

Some very sophisticated studies of Olympic racing kayaks show very minor changes in pitch of the kayak as speed increases.

I’m not sure if it is because of the reduced buoyancy at the bow and stern or simply the effect of a long narrow boat.

HEATH: But, if the bulk of the boat is partway down the hill and the bow does not rise as high trying to get over the hill,then that would probably less of an angle of pitch as speed increases. Not the usual oscillating pitch of the bow rising

and falling, but the permanent pitch as the boat tries to climb the Liquid Hill. Pitch is probably not the right term but I

think you’ll know what I’m saying.

I’m having a hard enough time getting my head around steady-state conditions without considering oscillation due to waves.

I am starting to believe that a West Greenland kayak simply doesn’t experience the same degree of attitude changing that

other “fuller bodied” vessels experience. The Liquid Hill is still there, but nowhere as pronounced as other vessels.

HEATH: Having a long, fine stern would allow the stern to sink further, but I would guess that helping the water to

move back into the place the boat used to occupy, more gently, would outweigh the lifting characteristics. Although of

course, the bidarka did have a fairly blunt stern.

I am going to build a baidarka hull for my test, there are always baidarkas at Delmarva, maybe we can figure that out.

HEATH: And, at the moment, I do not recall much discussion of how the boat interacts with sinusoidal waves, breaking

waves, and complex waveforms that are often found when waves coming from many directions and have many sizes

mingle. Anywhere within miles of a shoreline, or iceberg, you will also get reflected waves. Bouncing off the shorelinelike radar. In very complex patterns due to the exact shape of the shoreline.

Way, way, way beyond my mental capacity to understand physical phenomena. Also beyond my physical ability to handle in

my kayak.

HEATH: Ocean currents are famous for causing waves to be steeper and breaking sooner, then they would in a perfect

ocean of infinite size. Getting caught in the Gulfstream, with an opposing wind is a boater’s nightmare. Even though

the Gulf of California, between Baja California and mainland Mexico, is a large body of water, most of the people who

go boating there quickly notice that the waves tend to be squarer than normal ocean waves.

Experienced similar conditions in Bay of Fundy. Not a fan.

HEATH: All of these are factors that any ocean kayak must be able to deal with and survive. I always suspected that the

bidarka had the square stern in order to rise up in a following sea. Likewise the extreme flare of the hollow bow shape,

which when covered with skin, could only be produced by making their characteristic bifid bow.



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I am afraid that my understanding of the effects of hull design on the behavior of a kayak can’t support an intelligent re-

sponse; I simply don’t know the answers. I do know that as hard as I can paddle I cannot detect any change in the pitch of my

kayak. As

masik summer 2015

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