glassing upside-down....

[purvisgs]

Hoping for some tips as I have a large area around the centerboard trunk and minikeel (6" deep , 10" wide, 14 ft long, with opening in the center for centerboard, I also have to glass up into the trunk to get this edge) of my 37' tri to do, including around "corners" (ie the tricky part when you are right-side-up).

I have had some success with staples in the past so here is the current approach:

My plan is to put down epoxy, let it mostly harden, use light (4oz?) tape and put down a few layers (alternating mat), work out air, and staple it in place as best I can, then pull the staples once it has set up and do my best to fill all the holes with another coat of epoxy. Then repeat to get 6-8 layers of glass over all areas.

The mini keel is made of wood, this is a repair so the old glass has been ground way down, bare wood on most of the bottom (horizontal), old glass ground way back on both vertical surfaces.

Some areas I also may be able to brace from below, but these horizontal surfaces are not my biggest concern, the vertical surfaces and corners around the outside of the mini-keel and inside of the cb trunk are where I know I will have the most trouble getting it to "stick"

Any tips, suggestions, etc would be very greatly appreciated...

thank you!

[sailingdog]

I wouldn't recommend fiberglass mat with epoxy, as a lot of fiberglass mat is sized with something that isn't compatible with epoxy resins. Cloth or roving is generally stronger.

Provided you wet out the surface with epoxy, the fiberglass should stick to it fairly well, even on the vertical surfaces. The trick is to get the cloth to lay down on the first pass and not to have to manipulate it much.

[CellNav]

The best way would be vacu-bagging. There's a good article last month's THIS OLD BOAT magazine on the technique.

[purvisgs]

This is a common misconception about mat and epoxy... You can use mat with epoxy, I have been working with people who have done it for years... maybe not as structural, (or useful as in polyester resin application), but still very handy in some applications in my opinion... see here:

(sorry, I am a new user, so I can't post links, you will have to copy and past into your browser)

westsystem.com/ewmag/21/chopped.html

If the binder in mat is still a concern, I am sure that I have seen mat designed specifically for epoxy for sale for extra $...

Thanks for the vacuum bagging suggestion, not sure if I will go this way, but after setup, it sure would make things simple, (what type of bag would you use for an application like this (standard plastic sheeting or special nylon, ?), going around the outside vertical surface of the minikeel , around the bottom surface, and up at least a few inches into the ~4" wide trunk?)

I don't think that I will go with vacuum bagging in this case, but wouldn't mind hearing more, especially if you think this may be the only way that I will get an acceptable lay up...

thanks!

[knuterikt]

I would recommend using woven fibreglassfabric. Vacuum bagging will make it easy to hold it in place while curing, but you need a vacuum pump to do the job the rest of the equipment is easy to get hold of.
Without vacuum pump you must apply one layer and let it partly cure before you apply the next. If you follow this procedure you will avoid the amino blush giving a waxy surface. But if you build to many layers it might start to slide. Another way to avoid the amino blush is to use “peel ply” on top of every batch. When you remove the peel ply you will also remove the amino blush.