Patching fibergalss holes on a vertical surface?

[theFunsmith]

I've got a small hurdle to overcome. Please excuse the amateur nature of the question. Up to this point, my hole patching has gone relatively without issues. Tonight I began patching some holes on the transom. I started with holes above the water line in case I had less than optimal results. Structurally, I think the patches look pretty good, but I am losing resin from the patch as it drips down from the freshly laid cloth. I am using west systems resin and slow hardener. I was thinking that using a thickener might prevent good saturation of the cloth, and that maybe I am using too much epoxy. The main concern I have is, it goes together looking wonderfully, but after a few (10 or so) minutes, it appears I am allowing small air pockets into the cloth as the resin flows out of the bottom of the patch. As this is the transom, I can't rightly tip the boat upright to work on a flat surface. Any help here would be greatly appreciated.

[mshugg]

What kind of cloth are you useing. The reason that I ask what type of cloth is that some types of cloth ( I.E. 1708) have layers of CSM which assist in bonding between layers.  Some will say you don't need the mat when useing epoxy, but it doesn't hurt a thing and it builds up thickness faster.

Epoxy is thinner than other resins and it tends to flow out of gaps.  That's why silica or other thickeners are required when useing it as a glue.  I've had some success wetting out the cloth with unthickened resin, but spreading a thin layer of thickened epoxy into the hole prior to adding the layers of glass.  I find it better to saturate the cloth on a Poly covered piece of plywood or cardboard before laying it into place.

Also, plastic spreaders are great for eliminating voids and removing excess resin from the layup.  Bubble rollers help too.

[theFunsmith]

Thank you for the reply. I was using 6oz cloth, but have 1708 on the way. I think I will wait to do any more patches until the 1708 for the thickness building time savings. I will try a thickening agent in the resin to start, and will try wetting out on a different surface as well. I appreciate the tips a lot, you guys have been great.

[theFunsmith]

mshugg,

Just wanted to say thank you again. Got the rest of my transom holes filled this evening. They all came out excellent. I used the West Systems 404 High Density Filler to thicken up the epoxy to the point where it minimized running but still wetted the cloth and mat fully. The results were far and away better than my last effort. I cannot wait to see what it looks like once I get her rough sanded.

[mshugg]

Great news!  Congrats on your progress.  When you stat working with 1708, you'll probably want to use unthickened resin to wet it out.  Then use the thickened epoxy as a gap filler.  I don't use the thuckenef epoxy for standard layup, but it can be helpful when filling irregular surfaces.

[dirtwheelsfl]

Another option is to use a faster hardener, sets up quicker so it wont run out.  Sounds like youve got it under control though..