Fiberglass Repair

[Hankthelank]

Hello,

I have a hole in the side of the cockpit where the side mounted throttle used to be. I have been reading up on fiberglass repair, and the suggested way is to flare out the opening at a 12:1 ratio. My problem is that I have hardly any space to create any additional surface area. So i need to essentially patch it as is. The hole is roughly 4"x4". The surrounding fiberglass is cored with 1/2" plywood. Anybody have any suggestions on how to glass this opening.
cheers,
hank

[Ziggy]

A picture would help. What's on the other side?

[Stevens 47]

The 12:1 ratio is intend for a structural repair. Seeing that the hole already would have been a source for a weakness in the laminate, you should be fine to flare the area to what you can get. If it has a core thickness to fill you can fill it with a thickened resin. Then take a grinder and fair out the fill and the flare at the same time. If you have access to the back so much the better. Under fill with you layers of cloth then spread in a fairing compound prior prior finish sanding. Epoxy sticks the best.

[Finditsurfit]

It will be fine. Just make sure you prep really well and have at least and inch overlap all around the hole.

[Hankthelank]

Originally Posted by Ziggy

A picture would help. What's on the other side?

Sorry no picture, and am away from the boat for the next week. The hole is in close proximity to the cockpit floor, the corner of the cockpit locker and to a bulkhead on the inside.

[Ziggy]

If you can access the other side, I'd sand a few inches around the opening and epoxy a few layers of FG cloth. If it's adjacent to a bulkhead (inside corner) you can just laminate the cloth to the bulkhead as well. Then you can lay up a few layers of mat and maybe plywood from the outside to build up to the level to finish up with gelcoat

[beneteau-500]

look up Epoxy by the Leading Epoxy Manufacture | WEST SYSTEM Epoxy they have some pretty good video's on repairs and will give you and idea on what you need and can d0

[Hankthelank]

Originally Posted by beneteau-500

look up Epoxy by the Leading Epoxy Manufacture | WEST SYSTEM Epoxy they have some pretty good video's on repairs and will give you and idea on what you need and can d0

Thanks all for your advice.

Beneteau:

Thanks for the link. I was under the impression that it was better to use polyester resin for fiberglass repair then epoxy. Guess you just have to be extra careful during the prep.

hank

[SkiprJohn]

Aloha Hank,
Lots of ways to skin a cat but the way I'd do it is to cut a piece of ply the same size as the hole, mix up some epoxy and filler and filler the edges of the ply in place about 3/16" back from the surface you want to patch and let it set for an evening. Then, sand or grind about an inch all the way round the edge of the (used to be) hole, cut some mat and 10 oz cloth and start with mat alternate layers of mat, cloth, mat until you are just a bit proud of the surface you are wanting to duplicate. Once it is set up then sand it smooth, paint or gelcoat to match the rest of the cockpit.
I use nothing but epoxy. Some of my friends use polyester. In my opinion epoxy is better and you don't need to by West Systems. Any epoxy resin and hardener will do.
Kind regards

[barnakiel]

That is not the only way.

If the place of repair is inside the cockpit and not exposed to excessive stress then you can place an isolated (waxed) support inside and fill the gap with exact pieces of glass/epoxy. Fill it up to within 1 mm of the outer surface. Then remove the support from inside, wash off the wax (acetone) and lay up one layer of rowing/epoxy inside so that it overlaps some 1 inch outside of the repair area. Then fill up the cockpit side of the repair with thick filler with microbaloons (easy to level out later with the sander). Now the tricky part is - paint it over - so that the repair does not get dark in the sun. Two-part paint best but a one component will do, if you are not to picky. If you have a friend who is a magician, they may be actually able to match colors with the gelcoat but I found it to come out anyway after some time in the sun.

It is not the perfect way but it is strong enough and very easy to get smooth, pleasing finish.

b.

[Hankthelank]

Thanks all for your advice.

Skipr, i was thinking along your lines.

Barnakiel, although good, would your way of just using fiberglass require alot? The opening is close to 3/4" thick?

Thanks again, this site is excellent!
hank

[forsailbyowner]

I'd use polyester resin and save some money.can be had for quarter the price.

[barnakiel]

I would use polyester too, if it is a big and non-structural job. Epoxy sticks better but it is not an issue if proper key and overlap can be achieved. On the other hand if it is not a huge amount then the cost difference will not be very big. And perhaps best go with the type of resin you feel comfortable / have experience working with.

The thickness can be built up with some sandwich material - balsa, nomex, foam, plywood, etc...).

b.

[e hilton]

I have never done any fiberglass work. What is the difference between mat and cloth?

[barnakiel]

Huh. Do not know the technical English - but you have the loosely connected glass in the mat and there is also the woven material. You use them in different applications and sometimes you mix - I use the mat (heavy grade) to fill and build up or when the shape is odd. Rowing has more glass in it and it is laid out directionally - for me it is also easier to fill with filler and finish off - so I like to use as the last layer under the filler and then paint.

I worked with both polyester and epoxy and much as I like both, it was easier for me to control the pot life of the mixed epoxy - more time to make corrections if I blundered.

Try at WestMarine homesite - they used to have a fine tutorial there for the resins and about small repairs.

b.