I have doubt that once closed, it is fully waterproof. But my biggest concern about your design is that if there is a big wave and water enter the ring, there are no hole to make it evacuate. So if there is water in it and someone open the vent, all the water fall in the boat....

I agree With Yves-Antoinne comment, the design is very, very eye appealing both from the top and the inside part, especially the handle and I like it very much but as regards functionality I do have my concerns.

By the way, your work is featured in Product Design Hub. Congrats! http://productdesignhub.com/2012/01/luxury-yacht-improved-via-competition-with-community-of-over-80000-engineers/