Sheathing a Hull with Glass and Epoxy

Over the years Ive discovered a number of building issues which people find intimidating, and one of those is the process of sheathing a hull with glass cloth and epoxy.

As with most things in small boat construction, glass sheathing is not difficult, but it must be done the correct way if one is to avoid a bad result. It is just as expensive and time consuming to do things the wrong way as it is to do it properly, so some research and preparation is time well spent! There many correct ways to do the job, but Im going to give you a very brief insight into the method which works for me. Because of space and time limitations, this is just the most basic demonstration. I hope it helps.

Prepare surfaces with longboard and other sanders. Round-over edges

Fill gaps with epoxy and sanding filler

Re-sand all surfaces with 80-grit paper to provide a good "tooth" for the epoxy, and thoruoghly vacuum the dust

Fill any minor blemishes and sand details

Drape hull with glass cloth and cut roughly to size

Tape overlaping areas and edges in place with a few pieces of masking tape

Smooth out cloth with a dry brush held at about 45 degrees to the surface

Trim overhanging edges with shears or scissors

Ready for epoxy

I did one side at a time on this job, so I peeled back one side and held it in place with lead weights

Mix up small batches of epoxy, pour on in sections, and spread with a squeegee held at a shallow angle. Dont press too hard, or the mix will become aerated. Just gently move it over the surface and allow a few minutes for the cloth to wet-out. Dont worry about an even finish yet - just distribute the resin and allow the wetting-out to proceed on its own.

Attend to details such as the dry edges with a disposable brush

Continue working downwards until the whole section is completely wet-out. There is no rush, as long as you continue working out from a wet edge.

When completely wet-out, remove excess resin using a squeegee initially, and then finish off with a dry foam roller. The aim is to remove all liquid resin from the surface, leaving just the wet cloth with no puddles

The result should look like this - an even, textured surface with no pools of liquid resin. The glass cloth should be in direct contact with the timber, and not be floating in puddles anywhere.

Another good example of a proper finish after the initial wetting-out coat.

After the first coat has cured to the point where it has stuck the glass to the surface, but before it has fully cured, a second coat can be rolled or brushed on to fill the weave of the cloth. This is usually followed by a third coat a few hours later. In this photo you can see how the weave of the cloth has disappeared.

Here is the hull at a later stage after the hull has been sanded. Because of the fill coats, and the smooth application process, the sanding was done without cutting into the cloth - just the fill coats of epoxy were sanded.

For bigger jobs, extra hands are required to get things done before the epoxy goes off. On this 22ft hull, we had my wife, the owner/builder, and myself all working in a team

The result speaks for itself

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