Fiber Glass Sheathing of a wooden boat.

[BCB]

I am about to have a wooden boat sheathed in fiber glass. I am looking for anyone who has experience who can comment on preparation, specifications of materials to be used, application techniques (methodology) and any ideas on costs of materials and labour. Also, any disasters so lessons can be learnt.

[Raggi_Thor]

I think this has been descussed here before :-)
I think some keywords will be:
Very dry (max 12% ?) wood,
clean wood, no oil based treatment
epoxy (nothing else!)
enough glass to make it stable

[Hunter25]

Some construction types require fiberglass skins to incorporate part of the structural element in the design. Other types use fiberglass as a protective barrier from scratches and other minor abrasions.

Then there are some types of wooden construction that shouldn't be fiberglass skinned at all. These usually include the traditional methods, such as carvel, lapstrake, etc. Putting a fiberglass skin on these boats can cause rot to form and break structural parts like frames and stringers, because the fiberglass skin isolates and can concentrate loads in areas that previously did not have to bear these loads.

Many think fiberglass is the marine answer to nearly every issue, but it is not. It has its place, like the many other techniques, materials and methods used in boat building, but also has limitations and areas it should not be considered.

[frosh]

Hi BCB, why don't you provide more details of the boat and the reason for the fibreglass sheathing (in your opinion). Then we can give you better quality advice, including weights of reinforcement fabric. :)

[bluemarble]

I have a 40' Bruce Roberts designed Spray. It is made with mahogony strip plank construction. All of the strips are nailed and epoxied together. I would like to fiberglass the outside of the hull, but I am wondering what to do with the inside. I have heard that if I fiberglass both sides I can have big problems with water getting between the two layers of fiberglass and rotting the wood. But I don't want standing water in the bilge to rot the wood either. What would be the best way to go about finishing my hull?

Thanks,
Matt

[Hunter25]

The plans should have a laminate schedule provided. If you are finishing one off without plans, you should get them. If not, Bruce Roberts has a few groups located on the web where other builders can help you with the specifics of that design.

I would recommend you coat the inside with epoxy, until no bare wood is visible. Also, a light cloth in the areas of the bilge that will see some abuse, from dropped wrenches, winch handles, anchors, etc. Unless the plans call for it on the inside, being necessary for the structural requirements, then you do not need to apply cloth to the whole interior. I would not paint areas in the bilge, under panels, etc. so you can easily see if the wood is getting damaged from moisture.