I have several large chunks I can use in the Sea Flea .
It’s a closed cell foam and it’s pretty light weight.
Some open boaters pad out the entire side walls of their cockpit area with minicell plank for flotation, and to eliminate the space beneath the gunwale where water collects when the boat is heeled, or while rolling.
no odor, closed cell, light, and fairly rigid in block form. Only downside is it can be pricey.
Cellulite is good floatation too, easily
acquired. Stays with you.
I have several pieces left over
from other projects and my outfitter sells O and E at good prices.