what glass for covering thru hull hole?

I have removed a 2 inch diameter thru hull fitting in my fiberglass sailboat. The hole is underwater and the hull is ½ inch thick at that point.

My main question is regarding the type of glass I should use in making this patch. I will be using West System epoxy.

I have seen much info about doing such a repair, but what fabric exactly I should use remains a question. I would like to make the repair as strong as possible.

Some say use 1708. Some say 1708 with mat, some say 1708 without the mat. Some say 12 oz cloth would work.

My guess is that most any fabric would work, but I have to choose one. I do have confusion over chopped strand mat. I know there is the stitched type that would be compatible with epoxy. But is the CSM necessary?

If I had to do it right now, I would use 1708 with no mat….

I feel confident in my ability to lay up the glass from both the inside and the outside. The inside does not have as much room for tapering the patch, but I can still do some lay up.

So what fabric should I use?? Please, thank you!!

 

All 1708 will have mat in it. This is a "combo" fabric and the numbers tell what it is. The West System site has lots of information about the process and techniques.

http://www.westsystem.com/ss/repairing-machined-holes-in-fiberglass/

 

As said, anything with an "08" on the end has CSM, so you want 1700 or something similar.

Don't stress over the exact fabric, it won't make much of a difference in what fabric you use on a 2" hole, even the not so good ones will do the job well with epoxy.

 

I see. I should have said biaxial..

I have all the West info and feel confident that I can do the repair. I have done similiar above the waterline repairs.

I just need to pick a cloth.
which fabric is my only question...just looking for that answer.

thanks again.

 

Grind out the hole with a generous taper, so the new fabric can "tie" into the the old laminate and provide a place for the new cured laminate to live without a huge bulge. The fabric weight isn't as important as the total laminate thickness. Cut disks of fabric, that fit inside the hole and also several that will overlap the hole by at least the amount you've tapered around it. Wet out the area with neat goo and start applying pre cut fabric disks. Stack the fabric disks from smallest to largest, filling the hole first, then insuring plenty of old laminate overlap with the new stuff. Bagging this on would be nice, but you can do it all by hand. Consider some weights to mash the goo/fabric mess to the hull shell, until it cures. Lastly, you'll fill any voids with thickened epoxy, intally I'd use milled fibers and silica, but eventually you'll use a light weight filler, such as micro balloons. The goal is to equal the old laminate thickness with new material.

 

Thanks again. I think I get the idea now, LOL.
Appreciate all the help. Will post a pic or two.