I have a boat that does not have enough foam to suit me in case it gets swamped. It is a 15 foot aluminum jon boat with plenty of open space in the front and on the sides to add foam. My only option is to use the spray in foam, it has the lining inside of the the cross bars and the floor is covered with the checked plate aluminum. Does anyone have any knowledge as to how to proceed, There will have to be holes drilled to insert the foam but I can close the holes after filling?