Fiberglass question - best way to go about this repair?

[chuck in WA]

Hi gents. I picked up a 1980 Penn Yan 23' sportfisher last winter, but due to a busy work schedule haven't really had time to tinker with it much beyond some little things. One of the first big things I'd like to accomplish is to repair a worn area of the keel. This boat has obviously seen many rocky beach landings in it's life, and the fiberglass has worn through in a spot about 8" long. It has a "thin" area that runs an additional 3 feet which I'd like to re-enforce. The hull is solid fiberglass (not a sandwich) in areas other than the stem/keel and transom.

Any ideas on how to go about this repair? My initial idea is to build up the worn through area where you can see some rotted wood with epoxy thickened with silica or chopped strand mat, contour it, then apply 3 to 5 strips of fiberglass the length of the area I want to re-enforce. I wonder though, since this boat is too big to roll over, how will I ensure the fiberglass stays in place and doesn't develop air pockets while it's curing? I fear gravity will pull it away from the hull?

Also, what type and weight of fiberglass do you suggest for this? Application schedule (i.e. mat/cloth/mat/cloth/mat)? or something else? Should I consider roving for this?

I have a small Livingston dinghy that needs a very similar repair which I plan to practise on first.

My fiberglass experience: I built a wooden kayak kit a number of years ago which has a single layer of epoxy and fiberglass on the bottom/sides.

The pictures aren't the greatest, but hopefully give you an idea of what I'm trying to fix.

Thanks for your input!

 

[Bob_VT]

Re: Fiberglass question - best way to go about this repair?

Since it is under the hull and in a critical area I would use epoxy which is stronger and will adhere to fiberglass.

I would probably do it in pieces and possible use a sheet of wax paper and some plywood to hold it in place while it cures. Maybe a jack under the plywood to keep the pressure tight (same way if you use fiberglass) so air pockets do not form.

Yes Penn Yan with a tunnel drive by chance People used to take full advantage and run them in fairly shallow water and you have damage common to those hulls.

 

[chuck in WA]

Re: Fiberglass question - best way to go about this repair?

Thanks for the reply bob. Heh, heh, yup....tunnel drive boat. Very cool design IMO, and is really the main reason I (think) I'm willing to put some time into this restoration. They're very rare here on the west coast.

I definitely plan to use epoxy. How about the fiberglass application schedule? Should I use both mat AND cloth as I posted above? In what order would you all suggest? Would roving be appropriate here? (I don't yet even understand the difference between roving and cloth to be honest).

I suppose the ideal way to make this particular repair would be so use some type of vacuum bag setup. That would hold the fiberglass tight to the hull while it cures. Unfortunately I don't know much about the technique. Anyone tried this "at home"?

 

[Bob_VT]

Re: Fiberglass question - best way to go about this repair?

I would do it all with cloth not sure roving would be a good idea.

Take a look at these two posts and try to send the poster a PM (I know he is busy during the summer)..... This guy is a pro!

http://forums.iboats.com/showthread.php?t=317702

http://forums.iboats.com/showthread.php?t=317383

Take a look at the amazing photos. There is a vacuum set up in the pic's.

 

[chuck in WA]

Re: Fiberglass question - best way to go about this repair?

Thanks again Bob. Pretty amazing work being done in the threads you provided. And the vacuum bag setup actually doesn't look THAT complex. Have to do a bit more research on that.

I did some quick research, and found some good fiberglass info in this thread:
http://forums.iboats.com/showthread.php?t=286013
I think you're right about the roving - not really the proper product to use for this application which will need to bend around the keel. I also found a product that looks to be a combination of mat and cloth here:
http://www.jamestowndistributors.co...Fiberglass+Biaxial+Cloth+Tape+-+6+inches+Wide
That may be an ideal product for my repair. The research continues! Anyone else care to chime in?

 

[oops!]

Re: Fiberglass question - best way to go about this repair?

just a quick side note....of you are using epoxy....forget the matt....just use cloth.

there is no styrene in epoxy ....and the styrene is what breaks down the binders of the csm.

cheers
oops

 

[chuck in WA]

Re: Fiberglass question - best way to go about this repair?

I'm surprised to hear that Oops. I was under the impression that mat was a good idea since it helped the new work adhere to the old by ensuring there are no resin starved areas?

Would you suggest your peanut butter reciepe for a putty to build up the worn-through area of the keel?

I peeled off a layer of fiberglass tape that someone, at some point, had applied to the keel to try to beef it up. Didn't work.....it came off easily.

 

[Peteco]

Re: Fiberglass question - best way to go about this repair?

Use epoxy, not poly. I wouldn't use CSM at all, since CSM if damaged will be more friable than cloth. If it were me I'd lay down a tape of Kevlar on top after a few layers of cloth too.

Kevlar is the very devil to finish (it fuzzes) so lay a light layer of cloth over the Kevlar so it's easier to deal with. Kevlar is much more abrasion resistant and probably worth the trouble. Since the surface you are laminating won't be perfectly smooth and will have some small pits and such, use a structural filler with the epoxy like milled fibers, fumed silica or something as a base. Don't use microballoons except on the finish coat (if you even want to finish it that perfectly - it is a keel after all).

I'd consider vaccum bagging it but a hand layup should be fine. Taper the layers of cloth so you don't create a stress riser or subject the laminate to peeling forces.

Peel ply the top of the laminate with dacron or polyester peel ply. Just lay it up as if it were another layer of cloth. When it dries, you can tear it off and have a nice semi-smooth surface.

Download the West System book on repair:

http://www.westsystem.com/ss/assets/HowTo-Publications/Fiberglass-Boat-Repair-and-Maintenance.pdf