Leepod

Arpex will be equipped with a leepod. The leepod is an extrusion of the hull out to the oposite side of the ama. The idea is, that the leepod creates buoyancy at a certain degree of heel. As such, it would oppose the heeling moment, and prevent capsize. At least under certain conditions.

Its use is controversial.

I've built the boat model to test the functionality. The videos (posted here before - see archives) have showed me that the leepod does prevent capsize to a certain degree, and help reerect the boat if capsize occurs. Additional to the buoyancy effect, I have observed that when the leepod slams the water, a dynamic lift effect also adds to the stability effect. The angle of the front panel, between hullside and the extrusion, is key to that effect.

One negative aspect of the leepod is that it obstructs when going alongside a jetty. Since I don't plan for that, I don't care.

This illustration is for a shunting proa. It shows the proa form underneath, and the leepod is nicely seen. An additional benefit of the leepod is that it creates valuable roomspace in anotherwise very narrow hullform. It fits a double bed quite nicely.

Another element of stability will be water ballast tanks in the ama. I still have to work out how they will be operated. Handpumps and eletrical pumps are easy to find. Not too cheap, but the double system will be quite reliable.