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coolfinn-trimaran-sailing-1The Cool Finn trimaran is now sailing. We first got a glimpse of this trimaran under construction back in January.

Sailor Hans Schipper has built another beauty here. (His first one was featured a couple years ago in this post).

This “Cool Finn” combines the hulls of a Cool Cat catamaran with a main hull of a Finnjol dinghy. It goes against the norm by combining a relatively wide, flat-bottomed center hull with the slender beach cat hulls typically associated with multihulls.

Smaller tris similar in concept have been known to work … see here and here for examples.

I really think this is a lovely-looking boat. Hans’ workmanship looks amazing. I need to take some boatbuilding lessons from him … at least from the standpoint of aesthetics :-)

I’ll let Hans take it from here. He shares the following info and pics below. Keep in mind that his first language is Dutch.

Thanks for sharing this with us Hans!


Cool Finn Trimaran Sailing
by Hans Schipper

It took some more time as I expected but the cool finn is sailing now.

On the trailer I can put the amas straight to the centre hull, which makes the package 2.20 m/ 7 ft 3 inches wide. With the amas out it’s 3.65 meter or 12 feet wide.

The boat is about 16 feet long, with a total weight about 550 pounds.



I used 2 mm aluminium pipes. The inner pipes are lined with 2mm PVC pipe so that it slides easily.

The hull of the Finnjol has sufficiently strong edges on which the plexiglass adapters have good support. One of the original Coolcat rudders is big enough for a good turning ability. I did have to change the angle for mounting the rudder on the Finn.



On my maiden voyage I had no daggerboard and the boat sailed with too much leeway, so I placed a daggerboard in afterwards. This meant taking off the Cool amas so I could put the Finn (main hull) on its side to get the daggerboard in.

I made, just like the Triple A, about 90% of the boat with recycled or second hand materials. The mailsail an jib is from a Topcat.



I think the boat looks good because I used beautiful shaped parts of the Finn and the Coolcat which I could bring together with the two colors paint. The attempt was made to keep things as simple as possible.

Use of the ends of the tubes for the attachment of the stays with a strong piece of rope instead of mounting eyes. Just a lot of looking and thinking. That is why smaltrimarans.com is such a good place for finding the right solutions.



Two things were difficult: I had to give up my plan to make the center hull myself because what I tried, did not give the result I expected. You can see that on my earlier post. My wife told me I was very silent for some days. I was so lucky I found the Finn-hull at that time for €200 … That was about 20% from the price of the epoxy and glass/fiber I needed to make a hull myself.

The other difficult thing was the asymmetric work. How do I find the right place and angles for placing the pipes? I found my solution by making estimates and just doing it, saying to myself that it needs not to be perfect. I think that one inch deviation is not a problem for a boat like this ( my mother in law says “it is not an organ”). However it worked out well with my experience and good luck.


Minor problems?

A higher bottom was achieved with styrodur foam covered with crossed sticking fiber strips, which are used on seams of drywall. I filled this structure with bison fiber reinforced structural adhesive. It is light and seems to be strong enough but unfortunately the bottom is still too low in the front of the boat.

Because the self-bailers do not close so well, water enters the front of the boat still just above the floor when the boat is stationary . I was planning to make a tent over the cockpit to sleep in there. Because I do not like this kind of waterbed that plan has been skipped. It’s also possible the gennaker I bought may be too small.


Overall …

The boat is very stable because of the floating ability of the ama’s. I think I can handle at least 5 beaufort. I sail on lakes that aren’t very wide (Gooimeer Eemmeer lakes in Holland), also without swells that are too big. And with the shape of the hull and daggerboard it has little trouble with waterplants.

Hope to take this boat by car on a trailer to Friesland, Lauwersmeer and Waddenzee but I think that will happen next year when I know the boat better. And I also have to make it easier to put up the mast.

Until now the sailing feels a bit less spectacular than sailing with the triple A. Maybe it is because I still did not have the right circumstances.

The boat is easy to maneuver and goes well tack. It is very nice to lay on the trampoline steering with my toes in light weather.

I’ll be sharing more about how Cool Finn sails after a bit of time on YouTube. I still don’t know what the limits of this boat are. It has become a modern classic little tri. I’m happy with the result.