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composite sources/methods - links and questions
By:Jim Eisenmenger
Date: 8/31/2001, 8:30 am
In Response To: Design One, Whitewater Kayak *Pic* (Josh Guske)

Hi Josh,

You've had me thinking about building a composite boat - what is your general level of knowledge on the subject? Your design is complex enough that you will not be able to use any sort of wood stripping or plywood methods to create either the core itself or a plug for molding. However, I think you have no options other than building a plug and molding the boat around it.

My knowledge of this process is limited, but one difficulty is the plug material and shaping. I don't know what a cost-effective and workable material would be, nor how you would shape it. May be someone else here can help - maybe a two-part expanding foam??? Would that be stable enough to shape with hand tools?

Beyond that, your design is clearly a low volume rodeo boat - those things have very low tolerances in terms of just about every handling charateristic. My guess is that a small error in design could make your boat unpaddleable since there is such a small margin for error. Do you have a friend with a boat you'd like to duplicate? Maybe you could make a female mold from his hull as a base for your design?

Layups for the boat itself can either be a sandwich with a core of foam, fiberglass mat, honeycomb sheeting, or other materials and fiberglass or kevlar on each side; or simply multiple layers of a fiberglass or kevlar cloth. I think carbon fiber would be a poor choice - very expensive and used primarily for its stiffness. I think you want flex and impact resistance more - kevlar is excellent of impact resistance, but is also expensive. The primary disadvantage of plastic touring boats is thier flex and lack of stiffness - that is what makes these materials so good for whitewater. The stiffer the boat, the better for efficiency and paddling speed (although flexing can have different advantages). As you talk to experts in materials, be sure to emphasize you need flex and impact resistance and not rigidity. My guess is that a foam core with a few layers of a light weight cloth on the bottom of the hull (maybe some kevlar) and fewer layers of cloth around the foam on the rest would be a good option - but that is a guess - I have a book ordered and hope to learn more. Please don't go out and use these suggestions - I am not knowledgeable - I'm just trying to give you some starting points for your research.

Some links for materials suppliers who will likely also be great sources for information:

http://www.fgci.com/
http://www.acp-composites.com/
http://www.fiberglasssupply.com/

Jim

Messages In This Thread

Design One, Whitewater Kayak *Pic*
Josh Guske -- 8/30/2001, 11:09 am
composite sources/methods - links and questions
Jim Eisenmenger -- 8/31/2001, 8:30 am
Re: composite sources/methods - links and question
Josh Guske -- 8/31/2001, 10:48 am
Re: One off composite boat
Jim -- 8/31/2001, 10:21 am
Re: Design One, Whitewater Kayak
Les Nightingill -- 8/30/2001, 12:00 pm
Re: Design One, Whitewater Kayak
Josh Guske -- 8/30/2001, 11:21 am
accessing the image
Bret -- 8/30/2001, 2:04 pm
Re: accessing the image
Josh Guske -- 8/30/2001, 3:13 pm
Re: Design One, Whitewater Kayak
Josh Guske -- 8/30/2001, 12:00 pm