Foam in the Lisa b good shanty?

[ingers]

Hello and thank you for your time. I am a newbie and planning my first build - cost - materials etc... I live 1/4 mile from the Erie canal in Fairport NY and want to enjoy it more so I thought I would build something similar to the Lisa B Good. I had a few questions.

First while researching I ran across regulations that I have never heard mentioned in the shantyboat forums regarding flotation foam. That boat will be very heavy so I would need a huge amount of foam. Will I need it for that as it is 16' or should I just extend the length to 20' (which I don't want to do) so that it isn't required by the CG. I see bass boats and all sorts of boats under 20' with no foam. How does that work?

Any advice would be appreciated.
Thanks.
Mike