1 ton of foam?  Foam used in boating is usually in the 2-4lb range, which means 2-4lb per cubic foot.  There&#x27;s not much chance a 40&#x27; yacht has 1000 cubic ft of foam in it - far  more likely it&#x27;s got 20-30 cu ft, which is under 100lbs of foam.  Not enough to move the needle a bit.<p>Plus, foam provides displacement in case of breaches as a matter of it&#x27;s nature. This lattice wouldn&#x27;t provide any displacement, so a small breach would mean you&#x27;re 2&quot; thick composite hull would fill with water, which would be bad.