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How to Build Your Own Hull - the Lost Foam Method

There are a lot of kits out there, and more are cropping up every day. Having said that, the odds that a kit of the exact boat you're looking to add to your fleet being available every time is slim. You can chalk up one to the small hobby and move on to another boat, or you can get up and do something about it yourself.

Building your own hull is actually a pretty straightforward exercise and the shape of most submarines lend themselves well to a technique called the Lost Foam Method. In a nutshell, you build your model out of foam, lay up epoxy and cloth on the exterior, cut it in half, pull out the foam, and you're left with a perfect (well... perfect-ish) fiberglass shell.

With the help of some excellent videos put together by my good friend Dwayne Hill up in Quebec, Canada, I wanted to take a few minutes and run through the process, start to finish. The boat in the pictures and video is a completely scratch-built model of the Russian Kilo Class in 1/48 scale.

View the videos at the links below, and read on for a description of each step:

Video One: Plans, templates, foam and stacking

Video Two: Epoxy cloth, hollowing out the boat

Video Three: Control surfaces, rudders

Video Four: Inlets, grates, scribing

Video Five: Sail and periscopes

Materials and Tools Recommended:

-Two-part epoxy resin (West System)

-Fiberglass cloth (West System)

-Large scissors

-Disposable brushes

-Closed cell construction foam (Styrofoam brand by Dow Corning)

-Steel or fiberglass rod - 3/8" diameter and 6" longer than your model

-Razor saw or hacksaw


-Pencil or fine marker

-Masking tape

-Safety glasses

-Utility Knife

-Access to a band saw or jig saw (optional)

-Rubber gloves

-Hot glue gun

-White glue

-Automotive body filler

-Automotive scratch-filler

Section One: Do Your Research

Any project requires planning, and building your sub is no exception. The biggest asset you'll have at this point is a good set of blueprints, ideally one that includes loftings, or cross-sections of the hull at given stations along the hull. This will allow you to create the foam block outlines when you start cutting foam. Also ensure that you have the rights to use the plans from the original owner.

Now that you have plans, you should decide what scale you're going