stitch and glue method

8/15/2019 Stitch and Glue Method

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Stitch and Glue method

http://bateau2.com/howto/sg101.php

This new (2005) stitch and glue tutorial shows the building o a t!pical small boat"the #$12.

The #$12 is a new %ersion o our succesul #$11.

& protot!pe was built to test the new assembl! method. 'ictures were taen andthis new owTo *le shows e%er! step o the construction" rom reading theblueprints to the *nal coats o paint.

This tutorial is an excellent introduction to stitch and glue boat building,whatever the size of boat you intend to build. Almost all the techniquesdescribed below can be used for other designs including large sail andpower boats.

Stitch and glue boat building:

Defnition:

& stitch and glue boat hull is made o pl!wood panels assembled with *berglass

tape. +ontrar! to traditional boat building in which molds de*ne the hull shape" in

stitch and glue" the hull panels dene the shape.

This is important to remember: let the pl!wood panels tae their natural air shape.

&nother ma,or di-erence with wooden boat building is that the framing of a

stitch and glue boat is made of berglass. ust as in production *berglass boat"

http://bateau2.com/howto/sg101.phphttp://bateau2.com/howto/sg101.php


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in our designs" the chine" eel" bow etc. are made o *berglass.

Building Method Outline:

This ow To *le is di%ided in sections and ollows the steps taen to build the boat:

+ut the pl!wood panels or the sides and bottom

&ssemble the panels with butt blocs

+ut the rames and transom

&ssemble the hull: sides and bottom around ramesand transom

uild the *berglass seams on putt! *llets

nstall the seat tops

uild the rubrail#air the hull

nstall seg (eel)

Sand and paint

ou ma! be amiliar with the standard stitch and glue hull assembl! method. The

hull panels are benaround some rames. This is sometimes called the sharpie

assembl! method.

Step by Step


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$et3s re%iew the building steps beore we start:

1. +ut the side panels and assemble them with butt blocs:

2. &ttach the side panels together at the bow and insert the transom panel at the

other end:

4. nsert all the rames between the sides:

. #lip the hull o%er and co%er the sides with the bottom panel.


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5. #lip the hull and *berglass inside.

6. +o%er the seats and oredec" *berglass edges" 7ip and *berglass outside.

8. #inish b! installing rubrail" optional breasthoo etc.


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!utting the panels:

$et9s start b! drawing the shape o the panels on the pl!wood" one side panel *rst.

How to draw a panel (side) on the plywood:

"lueprints or patterns#

lueprints can be intimidating or *rst time builders and man! assume that ull sie

patterns will be easier. This is not true: ull sie patterns lines are di;cult to transer

to pl!wood and patterns are inaccurate. 'atterns are di;cult to handle and position

precisel!. plain how to use

dimensions.

Transerring plans dimensions to the pl!wood is eas! when done one step at a time.


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&s !ou can see" one side o the panel is straight and coincide with the edge o the

pl!wood sheet. That straight line will become the nice sheer cur%e when bent.

Terminology

(some boat part names used in this *le)

%sing dimensions# &ar' $oints

The panels drawing shows the dimensions o the side panel:


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Car a point e%er! 2@ along the edge o the pl!wood.


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This is how it loos with all the lines mared.

Ee>t step. $et9s put our pl!wood sheets together to draw the panel.

&long each %ertical line we will mar the points that outline the shape o the side

panel.


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n this case" the *rst point is at 16@ rom the edge" the ne>t one at 14/@.

Fraw all the points.


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The ends o the line are a little bit di-erent.

The tip o the bow and transom are not on a t!pical line.

The plans show how ar the! are lengthwise. n this case" !ou measure @ rom the

pre%ious t!pical line. eware" the dimensions ma! be di-erent on !our plan" this is

,ust an e>ample.


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Fraw a %ertical line at that distance.

&long that new line at @" we show the %ertical distance (o-set) along that line: 12

5/@.

Ceasure and mar the location o that point. t is the end o the chine cur%e" a

corner o the transom.

To draw the transom edge o the side panel" we need a second point" the end o the

sheer side.

That point" along the edge o the pl!wood is also not on a t!pical 2@ line.

The plans show how ar that point is rom the last t!pical line.

Car the end o the sheer line.

Eow" ,oin the two end points and !ou ha%e the transom side.


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'roceed the same wa! at the bow: draw a %ertical line" mar a point and ,oin !our

two points. This is !our bow edge.

Eow we ha%e three o the sides: the two ends and the sheer edge. Ee>t" we will

draw the cur%ed side o the panel" the chine side.


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$et9s start at the bow:

(ow to )raw a *air !urve


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&ssemble the 'anels

!ut a *irst $anel


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The plans show the location o that centerline.

Ase the same techniDue as beore to draw that centerline: use a pl!wood panel as a

straight edge.

+ut the ottom 'anel.

Eow that the pieces or the side and bottom panels are cut" we must assemble

them with butt blocs to mae long" one piece panels.

&a'ing +ong $anels with "utt "loc's:

$ong panels are made o se%eral pieces glued together with butt blocs. utt blocs

are pieces o pl!wood o the same thicness than the panels" epo>! glued. n the

case o the #$12" the butt blocs do not co%er the whole seam.

$et3s start b! assembling a side panel.


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Eote that the la!out shows the panels as mirror image: beware not to glue a butt

bloc on the outside o the boatI

eore appl!ing the glue" we recommend to prime the pl!wood with liDuid resin.

! resin is alwa!s made b! mi>ing two parts" the resin and the hardener.

Jpo>! resin is eas! to use. The resin loos lie a thic %arnish. ou must mi> the two

parts" resins and hardener beore application. &ppl! the mi>ed resin to the pl!wood

or *berglass and ater a ew hours" the resin will become hard and strong.

See our separate resin and *berglass owTo *les or details and e>periment with

our trial it.

luing the +ong $anels:


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Eote the paper under the seam to pre%ent the parts to become glued to the shop7oor. 'lastic sheeting is e%en better.

The butt blocs are generousl! coated with epo>! glue.

-poxy glue:

Jpo>! glue is liDuid epo>! resin mi>ed with wood7our to a peanut butterconsistenc!.See the owTo *les about resin" glue and putt! to learn more about mi>ing thoseingredients: http://bateau2.com/content/%iew/KK/2/

Glue the butt bloc to the panels and puts some weights on the butt bloc.


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Fo not appl! too much pressure. Jpo>! does not reDuire a tight *t Duite theopposite. !ou push all the glue out with too much pressure" the bond will ail.! to cure" ideall! o%ernight.Furing that time" !ou can cut the rames and transom. The rames are made ostraight lines. The! are easier to draw and to cut than the side and bottom panels.

ou probabl! will not need it but there is a separate detailed owTo *le that showshow to drawn a rame on the pl!wood and cut it: ow to +ut a 'l!wood #rame

*rames:

The side panels will bend around the rames. eore assembl!" we will add battensto the rames and drill some holes in the long panels or the stitches.

The #$12 rames are Lramed@. This means that we epo>! glue a batten all aroundthe rames but onl! on one ace. That ace will be the inside o the seats.

The battens add sti-ness to the thin pl!wood and pro%ide a good contact area orthe epo>! glue.Eote that this is speci*c to the #$12: most o our other boats do not reDuire an!battens around the rames.

http://bateau2.com/content/view/41/28/http://bateau2.com/content/view/41/28/


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The e>act section o the battens is unimportant. Jpo>! glue the battens to therames and transom.$oo at the the construction drawing. t shows that !ou need battens on one side oeach rame and on the inside ace o the transom. The battens run along the edgeo the rames e>cept or the transom where there is onl! a batten at the seat le%el.

That seat le%el is shown on the plans.


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(ull# Assembly:

Assembling the sides:


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The side panels are now stitched together at the bow. Turn them on edge and insertthe transom between them.

Transom and *rames Assembly:Stitch the side to the transom. Eote that the stitches are loose.


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nsert one o the mid seat rames between the sides.

Eote that the battens are inside o the uture seat bo> and that we push the rameagainst the butt bloc. The butt bloc is a locater.


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nsert the second mid seat rame" push it against the butt bloc.

The rames are held in position b! the pressure o the side panels but we will secureeach rame b! dri%ing two screws each side through the side panel in the raming.Fo not dri%e the screws all the wa! through" that would create a 7at spot in the


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side. Those screws are temporar!" we will remo%e them later.Eo epo>! glue is used at this point" all parts are *tted dr! *rst.

Two more rames must be installed: the ront and rear seat rames. To position those rames in the boat" we will use the seat tops.$et3s cut the seat tops *rst.

Aligning ith The Seat Tops:

n most o our boats" we recommend to assemble the hull beore cutting the seattops. The reason is that small mistaes ma! creep in and it is saer to checmeasurements against an assembled hull but the #$12 is so simple that we canmae an e>ception.

The dimensions or the seat tops are shown on the plans.J>cept or the bow seat top" we show those parts with our straight sides. Thecur%ature o the sides along the hull is so small that it doesn3t mae sense to tr! tocut a cur%e. The edge will be co%ered b! *berglass tape an!wa! and a gap is goodwith our building materials.

This is not wooden boat building. ception. t is a triangle with cur%ed sides. The sides ha%e agood amount o camber and we show it on the plans.

Those sides are simple arcs.n other words" we mar the three corners o the triangle *rst. Then" to draw acur%ed side" we *rst draw a straight line between two points. #rom the middle othat line we o-set a point b! the distance show on the plans then draw a smoothcur%e between 4 points: the ends o our straight line and that o-set point.


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+ut all seat tops.

Frop the rear seat top in the hull" push the rear seat rame against it and draw aline on the hull along the edge. ou will use that line to %eri! the alignment o therear seat rame.


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(The picture shows the bottom in place but all this is done without the bottompanel).

Bemo%e the rame and seat top" put them aside.

'roceed the same wa! with the bow seat: align" mar and remo%e parts.

"ottom $anel /nstallation:

+areull! 7ip the whole assembl!" bottom side up:


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& ew notes:

Mnl! the transom and the two mid rames are in place in this picture.


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&ll outside seams are taped. t step is to epo>! glue all the rames to the hull side and bottom.


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Eo *berglass is used in this step. Eote that we prime (pre coat) all suraces with

epo>! resin beore appl!ing the glue and that we smoothen the glued ,oint withliDuid resin. This gi%es a nice *nish and eliminate the need or sanding.

'roceed one rame at a time: i !ou remo%e all the rames at once" the hull will lose

it3s shape.


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*iberglass:

(ull *iberglass Seams:

The ne>t step is to build all the inside *berglass seams.


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*iberglass Tape and $utty *illets:

! resin between the side

panels and the bottom" at the bow and all around the transom.

Eo *berglass seams are reDuired along the rames.

actl! o%er the seams" not longer.

ou must prime all suraces that will be taped and we recommend to cut all the

pieces o tape in ad%ance" roll them and mar them.

To build those seams" we will wor wet on wet. This means that we do not wait or

the epo>! or putt! to cure between steps. epo>! resin and wood7our to the consistenc! o peanut butter.

&ppl! putt! in all corners" wor in one Lbo>@ at a time.

&ppl! the *berglass tape o%er the wet putt! and appl! resin to the *berglass.

#or a smooth *nish" brush epo>! o%er the *nished seam: no sanding will be

reDuired.


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Typical stitch and glue fberglass seam made o fberglass tape over an epoxy putty

fllet.

Epoxy putty fllet at the bow.

Some Tips:


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Spread the epo>! putt! with a tongue depressor" it produces the perect radius.

rush epo>! o%er the wet putt! and appl! the tape immediatel!.

#or a perect ,ob" use a *berglass lamination roller.

A fberglass lamination roller produces a clean and smooth fberglass seam with no

entrapped air.

Seat Tops:

The seat tops are supported b! small cleats:

'osition the seat top on the rame


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Jpo>! glue the cleats below that line. Casing tape will eep them in place while

the epo>! cures.

+oat the cleats with epo>! glue" drop the seat top on the cleats and build a putt!

*llet all around the seat top.

#iberglass the seams between the seat tops and the side panels.

The procedure is identical or all the seat tops.

$et3s not orget to coat all aces o all parts with epo>! resin beore installing them

in the boat. J%er! inch must be saturated with epo>! resin.


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n the picture abo%e" note the clamps.

This hull is *tted with an optional clamping board or use with a small outboard: we

double the transom pl!wood abo%e the seat.

The inside *berglass is now complete.

0ubrail:

eore proceeding to the outside *berglassing" we will build the rubrail.

The rubrail can be added at this stage or later" ater *berglassing the outside.

The rubrail adds tremendous sti-ness and strength to the hull and will mae turning

the boat o%er much easier.

! glued on top o each other.

Fo not replace it with a solid one piece rubrail. The laminated part is stronger"

easier to bend and can be made rom scrap pl!wood.

The rubrail is made o strips o 1/N pl!wood" 11/2N wide. The length o the pl!wood

doesn3t matter: smaller pieces are combined to co%er the ull length with o-set

seams between the pieces.


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The pictures shows pl!wood strips or the rubrail" coated with epo>! resin.

ou can use staples or clamps to glue the pl!wood strips.


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Note the home made clamps cut rom a 3" ! pipe.

The ends o the rubrail are trimmed" the edges rounded with a grinder and the

rubrail is generousl! coated with epo>!.

The hull is now read! or the outside *berglass wor.

#lip the hull o%er.

Mutside #iberglass:

&ll outside seams will be co%ered with *berglass tape.


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eore appl!ing the tape" we *ll the small gap between the two parts o the sideand bottom panels with epo>! putt!. This gap is the seam under the butt blocs.

'roceed the same wa! than or the inside seam e>cept that we do not need a putt!*llet. nstead" we round all corner with a Duic pass o a grinder or sander to aradius o 1/2H.

'repare !our *berglass tape lengths" prime the pl!wood and appl! the tape inepo>! resin. Eote the slit in the tape at the bow: this will produce a smooth cornerwithout air bubbles.


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Ase two plastic putt! ni%es to stretch the tape around the edge and sDueee outthe e>cess resin.


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#or a smooth *nish" appl! a plastic sheet o%er the wet epo>!. 'lain pol!eth!lene isperect. Ase a rubber roller to press the plastic o%er the resin" This will mae theedge o the tape almost in%isible and greatl! reduce the need or sanding. Theplastic does not stic to epo>! and is eas! to remo%e ater the resin cure.Mur builders ha%e nicnamed that techniDue Hpoor man3s peel pl!H.

This completes the *berglass wor on the hull. Mur ne>t step will be the installationo the eel.

1eel:

The correct name or this part is not eel but seg but we will use the name eel.

Some builders preer to install the eel ater airing the hull. Mn a small boat lie the#$12" the eel is not in the wa! o aring and we will install it now.

The dimensions o the eel are gi%en on the plans but !ou do not reall! need them.n the pictures" we used a 1>4 board that was la!ing around the shop but !ou canalso mae the eel rom a piece o pl!wood or e%en a 2>.


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! glue to bond.

$et3s clamp the board to the transom with a clamp and a batten.


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Car the rear edge o the eel" it lines up with the transom.

+ut along those lines and chec: the eel now *ts the bottom.&gain" do not worr! about a small gap" we want a gap.


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To *nish" round the lower tip o the eel. Eote the HtoolH used to draw the cur%e.

Bound all edges" epo>! glue the eel to the bottom (duct tape will eep it placeduring the cure) and appl! *berglass tape between eel and bottom.

&ll this was done without taing an! measurements.

*inish

*airing:

eore airing" chec that all suraces inside and outside are coated with epo>!

resin. #airing is not absolutel! reDuired. !ou are satis*ed with a wor boat *nish" a

Duic sanding and paint will be su;cient but most builders will air to a certain

degree or a better *nish. #airing is a two step process. The *rst step is airing or asmooth" air hull. Furing that stage we correct the une%eness o parts o the hull.


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ou can mae !our own airing compound rom epo>! resin mi>ed with a *ller or

wor with a premi>ed putt! lie Ouic#air. The airing putt! must be made with

epo>! resin. &uto bod! shop putties lie ondo are unacceptable. Those pol!ester

based putties do not bond properl! to epo>!" the! will 7ae o-.

'repare !our own putt! using a *ller made o a mi> o micro balloons and colloidalsilica. Silica cures to a %er! hard *nish but is reDuired in the mi> or thi>otrop!.


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The picture abo%e shows Ouic#air applied along the taped seam.

Thans to our Npoor man3s peel pl!N" there is %er! little to *ll.ible plastic putt! ni%es to appl! the putt!.

(ow to &ix 2uic'*air:

!ou mae !our own putt!" mi> !our resin as usual and add *llers to the desired

consistenc!: mae a *rm putt! or a slurr! depending on the ,ob.

To mi> Ouic#air is aster and easier.

Ouic#air is made o two components" a dar and a white paste.

ou must use two %olumes o the dar paste or one %olume o the white one.


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Tae two wood strips o the same width (paint stirrers) and mar them e%er! inch.

Mne inch o withe paste will be mi>ed with two inches o dar paste. until !ou obtain an homogeneous color and appl!.


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Sanding:

The sanding is usuall! done with a F&: a dual action random orbital sander. This is

the tool that !ou will probabl! use the most during the building o our boats.

&ter a ew passes" !our hull should be air and read! or the primer.

The goal o airing with putt! is not to obtain a surace read! to paint but to

eliminate all high and low spots" to produce a air surace.


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The high build primer will co%er sanding scratches" small imperections but will not

*ll large low spots. ou ha%e to decide when !our surace is air and read! or the

primer.

$rimer:

The primer can be applied with a roller or spra!ed on. Spra!ing is much aster and

can be done with an ine>pensi%e ?$' spra! gun. ! resins. Mur S4 primer is an epo>! resin.

Amine $roblems:

Furing the building o this boat" we assumed that !ou used Dualit! resins lie the

ones sold at oatuilder+entral.com. Cost o our resins ha%e a low amine content or

no amine blush. ! hardeners. Furing the cure" part o those amines

ma! not combine with the other components and migrate towards the surace.

&s long as the epo>! cross lining reaction is happening" amines will continue to

migrate to the suraces. That reaction (cure) can tae se%eral da!s depending on

the temperature.

This means that !ou can appl! a coat o epo>! on a pre%ious coat that is hard but

onl! a ew hours old without worr!ing about amine blush because the amine will

continue to migrate through the new coat.

owe%er" i the cure is complete" let3s sa! 2 da!s or more" there ma!be a thin *lm

o amine residue on the surace. That amine blush will pre%ent urther la!ers o


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resin or paint to bond properl! to the substrate.

n that case" !ou should lightl! sand the surace and wash the amine o- with a wet

rag or sponge.

ow important is itH t depends a lot on the resin. Mur S!stem Three Sil%er Tip and

our CarinJpo>! with slow hardeners will not blush and do not reDuire an! remo%al

o the amine. Mur other resins will ha%e a small amount o blush and should bewashed o- i the last coat has cured since more than 2 hours. Some ma,or brand

name e>pensi%e epo>ies produce a strong amine blush. n case o doubt" sand and

wash.

&mine blush eel and loo lie a light whitish greas! *lm. t is %er! ob%ious with

some t!pes o resins.

&gain" i !ou wor wet on wet or on one o our resins that is cured since less than

one da!" do not worr!" appl! the ne>t coat be it resin or primer without sanding.

ac to the paint.

ou should appl! se%eral coats o primer beore starting to sand. This will build up

some thicness to co%er the imperection.

&llow the primer to cure a ew hours" not more than a da!. The primer will become

%er! hard in a ew da!s and we want to sand beore it reaches that stage.

eore sanding" we recommend to use either cheap spra! paint or d!e maer in to

coat the primer. That HmaringH coat will show low spots and the sanding paper

scratches.


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The picture abo%e clearl! shows that there is still a ridge along the *berglass tape

and some low spots. Those areas can be *lled with more primer.

&s !ou progress" reduce the grit o the sanding paper.

&n amateur builder will probabl! be satis*ed with 150 grit at the primer stage.


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Some details lie a seat locer with a lid should be *nished beore appl!ing the *nal

coats o paint.

Top !oat and 3on4S'id:

The *nal painting is straight orward. t can be done b! brushing or spra!ing.

ou can appl! nonsid on the sole and oredec: use masing tape to de*ne a non

sid area and appl! paint mi>ed with nonsid powder.

ou can appl! nonsid on the sole and oredec: use masing tape to de*ne a non

sid area and appl! paint mi>ed with nonsid powder.

Eon sid is some t!pe o sand mi>ed paint. ou can ad,ust the roughness b! %ar!ing


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the amount o non sid additi%e.

& nice touch is to use a slightl! darer paint or the non sid and cut round corners.

"oot Stripe:

& boot stripe is eas! to paint.


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Mn a le%el 7oor" bloc !our boat le%el and using a stic" mar the boot stripe e%er!

10 inches.

oin the mars with masing tape.


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&dd tape along the other edge and paint.

The *nal touch is to spra! a ew coats o +lear +oat o%er the whole ,ob.

#or a perect gloss" sand between coats.

*inal )etails:


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Mur boat is read! to go but we sipped some *nal details worth showing: a painter

and oarlocs.

$ainter:

The painter is a line which goes through a hole drilled in the bow. The hole has beencoated with epo>! and painted inside.

& good not is all that we need" no hardware reDuired.


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5arloc's:

The oarlocs are mounted on a pl!wood pad epo>! glued to the inside o the hull.

That pad is made o scrap pl!wood. Fimensions and location are shown on the

plans.

Eote how the *nished boat does not show an! butt blocs or wooden raming: it hassimple and clean lines. t loos good and is eas! to eep clean.


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The a%erage builder can build an #$12 read! to paint in less than 20 hours but

considering that the epo>! must cure at some point" those 20 hours will be spreado%er 2 or 4 weeends.

stitch and glue method

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