THE SINKING OF THE VASATAKEN FROM:RICHARD E. FAIRLEY, MARY JANE WILLSHIRE, IEEE SOFTWARE JOURNAL, MARCH 2003,‘WHY THE VASA SANK:10 PROBLEMS AND SOME ANTIDOTES FOR SOFTWARE PROJECTS’

The Vasa, salvaged and restored in Stockholm

SINKING OF THE VASA Aug 10, 1628, Sweden’s most spectacular

ship ever, the Vasa, departed on its maiden voyage and capsized a mile from shore, killing 53 sailors

Why?

FACTS: King Gustav commissioned the

building of 4 ships in 1625:2 smaller ships, 108 ft keel2 larger ships, 135 foot keel

FACTS Ship to be based on

existing nautical technology proven production methods

To be built quickly

Construction started in early 1626 on the Vasa, as a small, traditional ship

Construction ended in late1628, with the Vasa being delivered as a large, ‘innovative’ ship

FACTS: Confusing changes to the requirements

were introduced:2 smaller ships now to be 120 ft keel (from

108), to carry more armaments (war w/ Denmark)

Then, Vasa was ordered to have 135 foot keel, to host 2 gun decks Problem: 111 foot keel already laid No expertise in Sweden for 2 gun decks

Builders decided to extend 111 ft keel, rather than lay new 135 ft keel

FACTS: Confusing changes to the requirements were

introduced: Vasa built 1.5’ wider than originally planned to accommodate

extra gun deck, but only in upper part of ship. This raised the center of gravity considerably.

Presence of 2 gun decks did not provide enough room for ballast

VASA CROSS-SECTION

FACT – ORIGINAL ARMAMENTURE INCLUDED THIRTY-TWO “24 POUNDERS”

36 ‘24 pounders’ 24 ‘12 pounders’ 8 ‘48 pounders’ 10 other smaller

guns

64 ‘24 pounders’

New Specs Final Specs

Final Implementati

on: 48 ‘24 Pounders’

VASA - STERN

FACTS: Henrik Hyberttson, chief shipbuilder,

became ill and died in 1627, midway through constructionHe took most of the tacit knowledge of

the ‘big picture’ with him to the grave, leaving no documentation.

Project planning and communication was weak, lacking detailed specs, milestones, workplans.

400 people in 5 different groups performed uncoordinated work

FACTS: There were no techniques for calculating center of

gravity and other aspects of performance and stability. Captains had to ‘feel’ the ship and make intuitive

adjustments.

Pre-launch stability test consisted of 30 men running across the deck from port to starboard.

Modern simulations have shown that, because of its haphazard construction, the Vasa would capsize at a heeling angle of only 10 degrees, and a wind of 4 knots. *

*4 knots is not enough wind to unfurl a flag on a flag post. It basically means that you can feel wind on exposed skin.

FACTS: The test was halted due to the violent

rocking of the ship. Not much room for ballast below deck Shipbuilder was unaware of the results of

the test; ‘If only the King were here’… The King demanded that the ship set sail

by July 25, lest the parties responsible be subject to disgrace.

FACT The Vasa Sank.

PROBLEMS/ANTIDOTES

Excessive schedule pressure Objective estimates More resources Better resources Prioritized requirements Phased releases

Changing needs Iterative development Change control/baseline management

PROBLEMS/ANTIDOTES

Lack of technical specifications Development of initial specifications Event-driven updating of specifications Accountability

Lack of a documented project plan Periodic and event-driven updating Baseline management of the project plan Accountability (designated project manager)

PROBLEMS/ANTIDOTESExcessive and secondary innovations

Baseline control Impact analysis Continuous risk management A designated software architect

Requirements creep Initial requirements baseline Baseline management Risk management A designated software architect

PROBLEMS & ANTIDOTES Lack of scientific methods

Prototyping Incremental development Technical performance measurement

Ignoring the obvious Back-of-the-envelope calculations Assimilation of lessons learned

Unethical behavior Ethical work environments and work cultures Personal adherence to a code of ethics

THE END(Or “Slutet” in Swedish)