The topic of foam cored kayak building surfaces every once in awhile on this Forum. Needless to say, there are still some lingering doubts as to the efficacy of the build process, especially in the areas of weight and overall boat stiffness.

Rather than dump a long rant on the gang, I'll let the example of two of the best boat designers and builders do the talking for me. There aren't any "yeah, but's" to contribute when it comes to who these guys are and the level at which they contribute to the sport. It's easy to find their respective CV's all over the web, as well as modestly mentioned on their own sites.

Greg Barton's name should be known by every serious kayaker in the world. His company, Epic Kayaks, is one of the names you have to include in the top three of any real test of touring/racing kayaks and surfskis when it comes to delivering performance. Home page: http://www.epickayaks.com/
Technical elements: http://www.epickayaks.com/tech/kayakanatomy

Epic has this to say regarding their manufacturing techniques...

"8.Lightweight, High Tech Materials. Epic kayaks are made with strong, durable, lightweight materials including carbon fiber, Kevlar, fiberglass and a specially formulated epoxy resin which is stronger and tougher than polyester or vinyl ester resin. Epic's sandwich core construction process with these materials ensures our kayaks are noticeably lighter than any of the competition.
9.Vacuum Infusion with Heat Cure. Epoxy resin is infused into our kayaks under full vacuum. This eliminates voids and produces Epic's signature high strength and lightweight standards. After infusion, our boats are post-cured at elevated temperatures to create the strongest and lightest kayaks on the market."

Ted Van Dusen is another name that sits at the table of elite designers and builders for not just kayaks, but also rowed racing shells and a whole pack of other types of craft, as well as filament wound spars. Home page:
http://www.vandusenracingboats.com/

Van Dusen gives this description of their build process...

"Hull Construction - Van Dusen racing boats are manufactured using advanced composite materials and space-age manufacturing technology. All our boats start with a pigmented polyurethane gel coat that bonds into the laminate during the curing process creating a strong, durable, and UV resistant outer layer. Depending on the hull laminate, we use pre-impregnated fiberglass and/ or carbon fiber cloth; custom-braided graphite and fiberglass parts; Nomex honeycomb, and syntactic cores. We were pioneers in the application of gelcoat, pre-impregnated laminates, vacuum-bagging and autoclave curing techniques to the manufacture of racing boats, and we have maintained a considerable technological lead over other manufacturers. Our kayaks, canoes, and racing shells are simply the lightest, stiffest, strongest, and most durable boats available today."

Many of the techniques used by both of these two companies are within the reach of a decently well-versed home builder, if they take their time to do the background, practice some with the materials involved and have an open mind as to the potential.

No, most of you guys do not have access to a supply of pre-preg carbon, but a well done infused layup at home is going to be within grams of the exotic and virtually unobtainable material.

Most of you guys do not have a kickin' autoclave, either, but you can make a post cure box at home that will do the trick quite nicely.

You can see for yourself, that there is no weight penalty involved for a properly engineered sandwich laminate at these hull sizes. It is true that these boats will not have the puncture resistance of a woone cored boat in Red Cedar. If you expect to encounter paddling situations where that becomes a big time reality, then you build a boat to suit your use regime and forget about arguing about the facts of one build style over another.

If, however, you want the lightest, strongest, stiffest boat that will give you the potential that is expresed by the elite athletes on this planet, or you just want to say that you build one just like theirs at home, then do yourself a favor and take a look at the possibilities and refuse to absorb the "conventional wisdom".

I've built a few boats in this build style over the years, as well as maintaining a wooden boat building interest. If there are any questions, please feel free to fire away. A few clever Googles on the topic will yield enormous resources that show you how it is done, what types of foams work best with which kinds of resins, to yield a terrific hull. They may not be kayak specific, but they will illustrate the techniques, which are the same.

Chris Ostlind
Lunada Design