there are tons of options out there, and what is right for you really depends upon how much weight you can budget for filling in between ribs, what you are comfortable dealing with, etc. For very weight sensitive ships I tend to use pink foam, block sanded to shape and then glassed. It does have one real big downside though, as your ships will like to roll when sinking if you are using it to save weight and you don't get your actual ballast low enough in the hull, so you have to be careful to balast correctly so that it does not induce an instability or list in the ship before it is sunk. After it sinks, I don't really care if it goes turtle, as I tend to design around an assumption of a roll, so everything is sufficiently tied down, anyways. Some use balsa to fill in, some spray foam, some ply, and a host of other options out there.
Poly Iso foam (pink builders foam) works well but hard to conform to odd shapes (you must sand, rasp or grind to fit). I like 6/10 foam from Alumilite, frame the area to be foamed mix small quantities and add to the framed area, keep adding till the area is filled shape the excess with a hacksaw blade and sand paper. Easy
From some pictures I have seen, It looks like a liquid that has harden, Anybody know what that stuuf is called
that would likely be concrete sealant. I would advise against that stuff. it works, but it is heavy and hard to get out if you screw up. I tend to like to put my mass in batteries and intentional ballast where I can control it.
Yep, this stuff is awesome and used in a few boats. No need to waterproof, mold it like clay. Use a little water before it sets and you can get it ultra smooth. If you have a mold, you can cast details...
Going to use this stuff in the Lutzow. Any insight as to how much "coverage" one boat would use? They sell it in a trial size and gallon size. I have a Bismarck and Scharnhorst to do as well so probably the gallon will be needed for me.
What's the shelf life of this stuff? Can I store it for months/years, or do you have to use it fairly quickly?
