Is this considered gelcoat? How do I fix?

[Darrow]

This is inside the cabin where the old instrumentation used to be.


How do I fill the hole, fiberglass from the other side and finish with some sort of gelcoat repair or epoxy?


Thanks all, sorry for the dumb questions

[kapnd]

Might be easier and cheaper to cover the whole area with Starboard or similar product.
Gelcoat and glass will be messy, stinky and costly, as well as labor intensive.

[Bellinghamster]

I agree with above unless you really want it to look like it was never there.
Approach depends on access to the back, which doesn't look like there is much. Also whether you want the back side to appear "finished" as well as the front.

Assuming that's a cavity too small for you to fit and work in comfortably, I'd fasten a packing tape covered backing board (1/4 plywood or similar) behind the holes using screws outside the work area. Tape around the edges on the back if you can (to control dust). Then use an angle grinder to bevel the edges of all the holes about 10:1 angle and build up layers of 1708 or similar glass from the "front", cutting and laying up progressively larger pieces to match the tapered holes until it's built up to the same thickness as surrounding laminate. I'd use polyester or vinylester resin - no need to use epoxy resin, but read up on the differences between laminating and finishing resin (laminating resin doesn't fully cure where it's exposed to air, so the next layup layer chemically bonds to it). Add wax to the resin or use finishing resin for anything you need to sand or you'll gum up the sandpaper. After it's cured pop the backing board off the back, grind and block sand things flat, fill low spots with polyester-based fairing compound and sand. Repeat until it's perfect, then spray matching gelcoat or paint of choice. Color matching is the hardest part!

[glenn.225]

What is size of hole? Doesn't look to be more than a foot square. Cut a piece of plywood, 1/8" thinner than than the bulkhead or whatever that is and glass it in with epoxy. Tons of YouTube videos will show you how to do this and get a nice finish. This guy gives good advice;

https://www.youtube.com/watch?v=JAtj...BoatworksToday

I've done several smaller patches like that, it's not very difficult and looks good as new.

[Fore and Aft]

Darrow the quick and dirty way would be to glue on a piece of 4mm black Perspex. Make sure you round the Perspex corners and sand the edges smooth. I have seen that plenty of times and it looks ok.
Cheers

[Don C L]

I think I’d look through a consignment store or garage sale for a really nice cabinet door, varnish it well and cover the whole area with it. If you still want access there, put hinges on it.

[boatpoker]

Originally Posted by Darrow

some sort of gelcoat repair or epoxy?

"gelcoat" is simply the shiny white finish layer that can be tinted to any colour. it may be polyester or vinylester, not epoxy. Epoxy suffers from UV degradation.

Thickness is built up with layers of glass fiber, mat (chopped strand stuff) or cloth (of various weaves depending on purpose) saturated in resin.

Some resins don't work well with some fabrics, some resins don't work well with other resins.

Perhaps someone can recommend a book on fiberglass repairs. It ain't rocket surgery but a screw up can be time consuming and expensive.

[JoeRobertJr]

Originally Posted by boatpoker

Perhaps someone can recommend a book on fiberglass repairs. It ain't rocket surgery but a screw up can be time consuming and expensive.

I use the West Systems fiberglass manual as a general reference. You can find it here: https://www.westsystem.com/instructi...r-maintenance/

Like glenn.225, I found the Boatworks Today videos helpful.

[boatpoker]

Epoxy is great stuff but is an unnecessary for many jobs that the less expensive polyester can handle quite well. Vinylester is also less expensive can can replace epoxy in most applications.

Are there any books out there that cover all three resins ?

[Spot]

Darrow,
-How big are the holes and how thick is the existing fiberglass?
-Is the boat indoors or outdoors?

The Boatworks Today videos are good. He also has some where he makes a replacement hatch and how to match gelcoat for repairs.

My head goes to making replacement fiberglass panels flat on a workbench and then adding them back into the holes with backing strips and a tapered and reinforced seam, similar to re-using deck skins on a core repair. Doing first laminations flat on a bench would be an easier introduction to glasswork for a person rather than trying to laminate something vertically in place.

[Darrow]

Thanks all, to answer some questions - access from the back is decent.



The hole is about 5" x 9" but there are actually 2 of the larger holes, this one is the largest. Both with decent access.



Will read up on some of the options (polyester, vinylester resin, etc. I don't mind putting in a bit of effort, but sanding does make a holy mess inside the boat.



The starboard option looks pretty decent and low effort if I want to slap something on there (I assume I would have to back the hole with something to give it some strength.

[Darrow]

Spot, to answer your questions it's about 1/4" thick it looks like

This is inside the boat, not exposed to water.

[JBP]

Originally Posted by boatpoker

Epoxy is great stuff but is an unnecessary for many jobs that the less expensive polyester can handle quite well. Vinylester is also less expensive can can replace epoxy in most applications.

Are there any books out there that cover all three resins ?

True, but polyester and vinylester both stink horrendously. Vinylester does not store for very long for your next project. The cost difference for small patch jobs is pretty small. I use polyester for big jobs or if I'm going to gel coat over it, but I'll use epoxy for small patches and anything indoors.

If you want quick and easy and don't need structural integrity you could patch it with a plywood plug and glass over it. Fairing and paint for a nice finish.

[s/v Jedi]

Quick and dirty is to put a cover over it as others wrote.

If you want it to look like it was never there, this isn’t too hard, here’s a good start: on Amazon you can find thin 2mm or 3mm pieces of fiberglass. You start by cutting pieces of the thinnest you get and glue that to the backside. Use epoxy glue, the 5-minute one is great for this. Keep it in place with masking tape until cured.

Now work from the outside: you fill the cavity with epoxy and more pieces of thin fiberglass. You can buy ready to use thickened epoxy like this: https://www.amazon.com/West-System-F.../dp/B08H8J4MCJ

Make sure that the fiberglass pieces do not protrude, use a straightedge to check. You can use as many layers as you like and it doesn’t need to be filled up perfectly, a couple mm short is fine. Let cure overnight.

Next step is prep for fairing. Use sandpaper wrapped around a piece of hose to sande the edges that stand proud, into the surrounding good gelcoat surface and check that nothing sticks out further than that surface.

Now you need to make a tool from a scrap piece of thin plywood: 5mm or 6mm (1/4” or less) and cut a piece with a straight edge. It must be long enough to span over the repair with 4” overlap on good gelcoat at each side. If there’s no room for that, go smaller but it becomes a bit harder to do.

Now you need the fairing compound. I recommend TotalFair or Awlfair. Mix some, use a putty knife to put it on and the piece of plywood held at 45 degrees to the surface to smooth it level with the surround.
Let cure. You will find it has shrunk. Sand the surrounding gelcoat area so that it’s nice and flat to be used as a reference again and repeat until you can sand it completely and it’s to your liking.

For finishing, paint with primer and topcoat. Simple one component like from TotalBoat or go 2-component like from Epifanes, Awlgrip etc. I recommend to paint the whole surface. I can stop at corners incl. Rounded corners where it’s impossible to see where I stopped. Use masking tape and after cure a scraper (even the blunt backside of those break-off knife blades work) to blend it in.

The above repair does not provide much structural support but it good for these kind of jobs. It isn’t much work as expressed in hours but requires curing etc.

[Spot]

Darrow, thanks for the hole dims and glass thickness.

-Do you have materials at hand or would you be sourcing all new for project?
-Are you set on using gelcoat or is paint an option?