Mold Making

I have my USOM hull off the plug and now need to make a couple molds for some of the innards (keel box/mast step). What is the best way to make a mold? I was planning on a layer or two of lighter glass against the hull, built up with 2-3 layers of heavy glass. Is that too much or too little, do I have the right idea? Thanks alot.

that sounds about right milrtime, however, it might be easier to build balsa structures and wrap them in F/G.

You think? Even if I have the plug built and everything? I guess it wouldn’t be too hard to do that, but I think a mold straight off the plug would be more accurate which is critical since the product of the mold will need to fit directly into the hull without deforming in any way.

if you have the plug built already then by all means use it! i just figured that if you hadn’t built the plugs or mould yet than it was probably better to go sailing… but there is absolutely nothing more satisfying that using parts that you have pulled from your own mould. it you have the plugs, i would do it!

hi. there is a good article on mold making here:
all kinds of good stuff there as well.


Thanks for the help, I think I am going to about it my way and see how it turns out. it will only require a small amount of material so there isn’t much at risk. Thanks again.

that is a great article. i have been using popsicle sticks to seperate the parts from the mold. i use most of what they suggest. the pva and the mold release wax. the only thing i do is put the wax on think. after rubbing on 2-3 layers of wax. i put a real thick coat on at the stern. then take a small torch and melt the thick wx and let it run down the hull
i know poeple will say that this is not a good idea . you run the chance or wrecking the mold. and i did not know this, untill i saw a pro do it with automotive parts. now i do it myself
good luck with you parts

that actually is a good idea. some people put a new mold in the oven to warm it a bit, then while it’s warm, they start the wax job. the surface pores are a little more open, and absorb the wax deeper: however, todays waxes seem to penetrate pretty well.

I’m going through that very process myself and keeping it documented at Team Seacats. If you click on “One Meter” in the categories on the left, it will filter out all but the one meter project updates.

I reently saw a TV show about something like this ( i.e. Discovery Channel’s How it’s Made.)

Silicone rubber mold-making (doll-making stuff) stuff is coated over the part right there in the field (or the shop.) After it cured, it was removed, filled with acrylic resin (or whatever) and, after the resin cured, machined just a little to add detail or remove unwanted resin. Then a more sturdy fiberglass mold was made from the resin part.