Glassing over a large hole in my "boat".

[pete c]

Hi everyone. I am new to this forum and to be honest, I don't own a boat. Well, I do have a canoe. I also own a Toyota Sunrader, which, structurally speaking is a fiberglass boat.

These Sunraders have wraparound plexiglass windows in the cabover section. These windows suck. They don't open, and are very prone to leaking. I broke a replacement window in two attempting to wrestle it into place. Part of the problem is I don't know what the hell I'm doing and part, the replacement windows aren't a very good fit to begin with. So, I now intend to just yank them out and fiberglass over the holes. The fiberglass is about 1/4 inch thick. The hole is roughly 1 x 4 feet.

I have done some reading on this subject and the prefered method appears to be form it on the outside, bevel the hole on the inside. Spray/roll the gelcoat on the inside, lay up the glass, remove form, do a little polishing on the outside and viola!

I talked this over with an experienced autobody repair guy and he says he would form the inside, lay up the glass on the outside and apply the gelcoat last. His rationale is that doing it on the inside is a PITA for a few reasons. I tend to agree.

My experience with fiberglass is just a few small patch jobs to reinforce an RV vent cover that I was too cheap to replace. It was a bit messy, but, came out fine. I am generally handy with this sort of work and am pretty confident I can do it, although I suspect that when it gets to the gelcoat finishing, I'll just drive it over to Kevin and let him do that as he has a clue in such matters.

Any advice would be greatly appreciated. I would particularly like info on how much/where to buy materials.

Thanks,

Pete

[SkiprJohn]

Our local Ace Hardware has fiberglassing materials but I don't know where in the world you are located. West Marine, local surfboard shop, etc.. Check out your local yellow pages for fiberglass. If you do the patch in epoxy you will not be able to Gel Coat so do your repair in polyester resins for a Gel Coat topcoat.
A photo of your project would help. Local fishermen would just take a piece of plywood and screw it over the holes. As I understand it you want to do a good cosmetic job and have it shaped the way the plexiglass used to be.
kind regards,

[SkiprJohn]

I just looked up what a Sunrader is and understand now that you want to cover the front end of your RV where the large window was. I think that's a good idea. I see that the plexiglass has a curve round the edges and that's where the problem is. I'd use a backing of thin plywood attached to the inside and glass over that from the outside. Just my opinion.
kind regards,

[pete c]

Yes, John, that is just what I intend to do. For the curved section, I may use a sheet of some sort of plastic as I do not know if plywood will follow that tight a radius (approx. 2").

And yes, we do have an Ace Hardware. They do have fiberglass. I saw a quart can, I think. It was about $45. Does this sound about right?

So, I am looking at about 8 sq ft total, 1/4" thick. Will a qt get me through? How much fiberglass will I need?

[pete c]

What I think I will do for the form is use 2 pieces of flat plywood, maybe 1/4" thick. Cut them so they overlap a few inches. Screw them to the inside of the wall. For the curve, get a piece of maybe 1/8 plastic sheeting. Glue it to the plywood . Such a piece of plastic ought to follow the curve nicely. I will taper the exterior with a grinder about 12-1. Do I need that much taper? 3 inches of taper would result in getting into the curve of the shell. I'd rather not do that. I figured a few coats of glass across the inside afterwards would give me plenty of strength.

I will use wax paper between the plywood/plastic and the fiberglass so it releases.

This form will be able to do both sides. Will do one at a time.

Assuming I want to have my bodyshop guy do the gelcoat, how far beneath the surface should I stop glassing? I was thinking about 1 mm.

[pete c]

FYI. This is a Sunrader.

toyota sunrader - Bing Images

[Sailmonkey]

here's a tutorial on youtube, If I read your post #5 correctly you're on the right path, but I think you'll need closer to a gallon of resin to fill wet out the glass for the area you're talking about.

West System Fiberglass Repair Howto Part I - YouTube

[pete c]

Just had another idea on how to do this.

Rather than laying the entire thickness in glass, how about screwing the plywood to the inside, then gluing/screwing a 1/8 piece in the hole on the outside. This piece would form the curve and cut by over half the amount of FG needed. The interior piece of plywood would remain. In fact, I think that piece will run the entire front wall. Might even use something with a nice surface and have that be the front finished wall.

[SkiprJohn]

Aloha Pete,

Yes on the 1/8 piece. You don't need a 12 to 1 ratio on the grinding in that it is an RV and not a boat and wind will be your pressure not water. Half that should do it.

I don't know the prices of resin because I buy epoxy resin for projects in bulk 5 gallons at a time.

But that does seem a bit high for polyester resin. Like I said polyester is compatible with gel coat but epoxy is not.

kind regards,

[pete c]

Well, it's time to get started. I have a question about the fiberglass. Should I use regular cloth or should I alternate between cloth and mat? I understand that the mat is used to fill in deeper areas. How many layers will I need if I used just cloth? How thick is mat?

Next question is regarding the finish. There have already been cosmetic repairs done and it seems to be bondo, it is grey. Should I just use bondo on the surface? Does it adhere well to fiberglass? Is it best to let the fiberglass fully cure before applying the bondo?

[SkiprJohn]

There are many different thicknesses of mat and cloth so it is hard to say how many layers you will want to use. My own personal preference is to use mat between layers of cloth but start the first layer with mat because it adheres to the plywood better. Bondo will not stick to epoxy so make certain you are using polyester resins if you intend to use bondo. You can also mix up some microballoons in your polyester resin to use as a filler instead of bondo. Bondo will stick to the unfinished polyester.

Check out "The Fiberglass Boat Repair Manual" by Allan H. Vaitses from your local library if you have questions about what you are undertaking.
kind regards,

[SkiprJohn]

Make certain that before you start using the resins that you mask off any area where you don't want them to make a mess because certainly there will be some splatters and runs.

You might want to try a test batch on a piece of ply just to see how much build up you get with a couple layers of mat and cloth.

kind regards,

[pete c]

Well, got started today. It is coming along ok. I did learn a few lessons.

You add hardner to resin, not resin to hardner. My first batch got a little lumpy.

Lesson two is that when it gets lumpy, dump it. Putting cloth over lumpy resin is a bad idea. Results in much grinding to fix lumps.

Oh well. I am doing this job for someone else. Not making enough to make it worth while, but, the experience I am gaining is worth more than a few bucks. I have all sorts of other things I'd like to do with fiberglass after I get comfortable with it.

[pete c]

Looks like I taught myself another lesson.

After grinding the bumps off from my first screw uo, I may have made an even bigger one.

I washed the surface off to get the dust off. In doing so, I got some untreated fiberglass wet (with water). I set it aside to dry. It was still damp when I used it, kind of thinking to myself this might not be a good idea.

Now this morning, that fiberglass isn't even beginning to set. So, I peeled it off and I have a sticky surface under it. I can't imagine that the next layer will adhere to this worth a damn. I tried cleaning some of it off with lacquer thinner but, that seems to also loosen the good layer underneath.

is it time to rip it out and start over ? I hope not. Is there something that will clean this surface without raising the surface beneath it?

Getting experienced sure is a PITA sometimes.

[atoll]

Originally Posted by pete c

Looks like I taught myself another lesson.

After grinding the bumps off from my first screw uo, I may have made an even bigger one.

I washed the surface off to get the dust off. In doing so, I got some untreated fiberglass wet (with water). I set it aside to dry. It was still damp when I used it, kind of thinking to myself this might not be a good idea.

Now this morning, that fiberglass isn't even beginning to set. So, I peeled it off and I have a sticky surface under it. I can't imagine that the next layer will adhere to this worth a damn. I tried cleaning some of it off with lacquer thinner but, that seems to also loosen the good layer underneath.

is it time to rip it out and start over ? I hope not. Is there something that will clean this surface without raising the surface beneath it?

Getting experienced sure is a PITA sometimes.

use acetone instead of laquer thinner!
laqurer thinner is celulose based and will not dissolve uncured resin,aceton evaporates 100% and leaves a dry contaminate free surface.

cellulose or water will act as a barrier to a chemical bond.

for best results clean with accetone,then grind,then clean again using acetone before using resin with 1-2% hardner.