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During my latest sanding episode I discovered that the builder of my Tangaroa neglected to glass one of the beam troughs.  The wood under the paint was wet but not yet rotten so I think I caught it before it became a major problem.  I'm going to put some glass in there but wondered if there is any particular way it needs to be done to be sure it is water tight.  Thanks.

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Hi Brian,

You have just to dry the wood carafully and check it dry aroud the area, then glass it with epoxi resin.

Cheers,
Tarcisio.
Oh, was that the beam trough that doesn't need glassing? WTF!

Know that product Git-Rot? It's a slow curing epoxy impregnated with a fungicide that you inject into predrilled holes. Might not hurt to let that trough have a Git-Rot treatment prior to glassing. It takes about a week to cure, but it turns old ply into epoxy space material.

Are there fillettes at the union of the beam trough floor and bulkheads? If not you can easily make them. You will need them for glassing, so that your glass can make that bend from beamtrough floor up to bulkhead side.

It will be watertight after you glass it. 2 layers of 6 oz? Is that what your plan says?
If you start on deck about 5 inches from the trough, then go down the side of the trough, over the base, up the other side, and another 5 inches onto the deck, you'll be solid. I guess you could do the first layer with scraps, as long as you don't neglect where the wood is joined...but then it would be weak, like a little girly-man.
West system recommends heating the area you are going to inject and heating the resin then heating the whole area once applied--this thins the epoxy and supposedly allows it to soak in the same as Git Rot. Something else I have been doing is using a paintable preservative (zinc or copper) prior to covering with epoxy and polyester--they recommend 3 days drying time
Dry it with heat lamps, it will take a while, and saturate with borate preservative, but first poke it with an awl and gouge out any soft areas. In retaliation of many dentist visits I used an air die grinder with a ball shaped rasp bit to remove unwanted suspicious wood. Some punch borate rods into the wood. The problem is that the moisture doesn't just hit the surface, it goes deep into the wood, making it ripe for rot. The epoxy provides a moisture barrier, but if the moisture is already somewhere in the wood, a situation develops that moisture condenses at the moisture barrier and then degrades the wood immediately at the surface at the epoxy. Checking can crack the epoxy and soon you have a plastic epoxy encasing a rotting mass. The key is to eliminate moisture and heavily encase the wood in epoxy. I like epoxy filled with glass roving mill ends. It's heavy but strong. Also a slurry of epoxy and micro balloons at a consistency of fudge frosting to top it off and some quick fairing of the mess with a flap disc will provide a thick vapor barrier. Two part urethane without reducer in two coats will prevent UV damage. Or, you can chainsaw out the suspicious piece and scarf in a new section with the same surface treatment.

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