Change of plans, from catamaran to box keel

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My initial plan of a catamaran hull has advantages, like being super stable and having lots of storage space down low. Parts of the hulls can also be sealed into flotation chambers to keep the vessel afloat in case of an emergency.

There are definitely also some disadvantages, the biggest being the lack of interior space. The tunnel in the middle means standing-height in the middle isn’t really an option.

So I’ve been thinking about changing the design to a box keel hull. I would sacrifice some stability for a more practical interior. The keel would have to be wide enough to provide some walking space, but small enough to not push the boat up and make it want to tip over. For now I’ve made it about 70 cm wide and 20 cm deep. This gives is about 400 kg upward pressure, which should match the weight of the empty vessel.

Time for another prototype…

1:10 scale box keel
Weighed down with the equivalent of 400 kg, the designed dry weight of the boat
An additional 180 kg to scale, simulating 2 people and some equipment. It all looks good so far…
The same 400 kg dry weight + 180 kg cargo all at one side

As the last picture shows, the box keel is not as stable as a catamaran. By far. I will not be able to carry  the 10 or 12 people the catamaran could. But all in all it does seem to hold up, even in pretty extreme situations. Good results. I think box keel is here to stay.

Until next time…

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