Below is a picture of Sea Sled 1, my skin-on-frame catamaran kayak prototype. I tested it on Wednesday at the Maritime College waterfront which is on the East River in the Bronx. That's our cadet training ship in the background.

The boat is designed as a swimmer escort and rescue boat. The idea is that a swimmer or rescuee can rest between the hulls in the stern with their arms over the aft decks. For the rescue capability I will be adding a hammock of some sort between the hulls to allow getting a person up out of the water to slow hypothermia, if necessary. To allow for the extra weight of a passenger, the seat-footboard assembly will slide to allow for re-trimming the boat on the water.

Boat specs: hulls 16'6" long, max beam ~6", max depth ~15", hull spacing 16", max overall beam about 28", max beam at paddling location ~25". Weight about 50 pounds (estimated). Initial design was done with Kayak Foundry - thanks to Ross for the package.

The design is partly an engineering exercise, and I hope to get some of my students to work on improving the design and coming up with further adaptations. I'm not sure that there's actually a market for a rescue boat, but I think it will be a good perimeter safety boat for beaches and long distance swims. Due to its stability it would make an excellent fishing or diving platform. I'm hoping to exploit the extreme narrowness of the hulls so it will be fast - I could see it as a fun open-water racing boat if the drag can be lowered enough.

The plastic wrap kept water out for an hour or so, and gave me (in the hat) and a student a chance to run it around our enclosed harbor quite a bit. Here's the major results:

1. It is ridiculously stable - I could stand up in the seat without trouble. If you sit side saddle and hang your legs over the outside, it lists about 20 degrees and stops. It took a major effort to capsize - righting it was difficult as well, but doable by one person. Leaning the boat is none too easy.

2. It does not like to change direction at all, but once it gets going the glide is quite significant. It was physically difficult to turn, which makes sense given the hull geometry. I could close my eyes and paddle hard, open my eyes and still be pointing at the same target. I am designing a rudder now. A couple of people have suggested a rudder in the bow to keep the aft rescue space clear, which sounds worth considering.

3. Although the boat twists a little around the crossbraces when being handled out of the water, in the water I didn't notice any relative motion between the hulls, which I find surprising, although conditions were benign. I could save some weight by downsizing the crossbraces and connecting hardware.

4. Drag was high, although the major portion appears to have been caused by major wrinkling of the plastic all over the hulls. It's true that skin friction will be high because of the extra wetted surface on the insides of the hulls. The test was promising enough to go ahead and put on a nylon/goop skin to see how much drag is eliminated. Skinning will have to wait for the rudder design.

5. Hull wake interactions become noticeable at about 4 knots - the surface of the water between the hulls developed a standing wave pattern. I need a waterproof camera to get some views of this once the new skin is on.

6. Although the seat felt high, it was not as high as the SOT that we used as a chase boat. The cat hulls did not interfere with the paddle stroke, which I was worried about. A high paddling angle was doable. Best results were had with a 230cm Euro paddle with a big blade area; my GP felt pretty useless, and my Exception AT with a smallish blade felt underpowered. That may be because of the high drag, the new skin will tell. It should like a wing paddle - I have one, but am not adept yet, so that will have to wait. The seating was very comfortable and I will go ahead with a sliding version with a fiberglass seat and footboard with a gas pedal rudder control system.

OK, I wrote too much - I'm pretty excited that it worked at all. I don't know that this is really a kayak - if nothing else, it is technically a sit on top. I'm calling it the Sea Sled, which is maybe a good term for this type of paddleable catamaran in general. Anyway, any comments or bright ideas are welcome. Cheers, Carl.