I don't know anything about this, but this is what I found by googling:

The ship design spiral process focuses on what the ship needs to carry. Typically ship machinery is dictated and the owner has decided to buy a certain type of engine or the Navy has a certain machinery system which plays a very important parameter in terms of cost and complexity. From there, the shape of the hull form and displacement are considered, because the ship has to float. "TGIF, to a naval architect does not mean Friday, it means floats," Day added. Then the next step, in ship design, is powering. Existing machinery and fuel conservation must be considered with waves and stability. With the advent of computer-aided design and concurrent design, many of these tasks are completed simultaneously.

http://www.globalsecurity.org/military/systems/ship/design.h...

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Note added at 15 mins (2009-05-15 17:34:11 GMT)
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http://books.google.co.uk/books?id=RsNaur9QzkkC&pg=PA3&lpg=P...
The Design Spiral for Computer-Aided Boat Design
This article describes the overall boat design spiral process and its relationship to modern computer-aided design and engineering tools. Each major phase of design (design statement, conceptual design, preliminary design, and detailed design) is discussed in detail with examples of how the computer can effectively optimize the boat and speed the design process.
http://www.newavesys.com/spiral.htm

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Note added at 18 mins (2009-05-15 17:37:27 GMT)
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Glad to hear - more by luck than judgment really. Best of luck with it!

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Note added at 6 days (2009-05-22 10:36:01 GMT) Post-grading
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Thanks for the points, Lutz