Crack in Fiberglass - need help

[parmtree]

Hello all.
I purchased my Trillium last year, knowing that there was some sort of "crack" underneath this metallic tape starting at the top left edge of one of the windows. Anyway, as I was removing a window to reseal with butyl tape (had some leaks last year), I removed the metallic tape to reveal a more substantial crack than I had envisioned. See pics. I searched a bit on this forum to troubleshoot this, but I'm still at a loss. I'm just not sure how serious this crack is....ie is it something I just buy Captain Tolley's crack sealer cure for?

Would appreciate some guidance.

[deryk]

Ouch! Well relax it is fixable. A bit harder because of the color of your egg. Are you planning on painting it? Generally I would open the crack up a bit and sand the surrounding area and lay up some cloth and epoxy...sand it smooth and paint it...I never got into re gelcoating and most of my cracks on my boat were under the waterline so was easy to hide with bottom paint.

There are products of thinned epoxy that you can apply to let it seep in and harden....if the crack is visible on the inside under rat fur or carpetting I would sand it down to bare glass and layup a few layers of cloth and epoxy to strengthen the repair.Wood preservation, rot repair, and restoration using epoxy resin on boats, homes and log homes.

[David Tilston]

The first question is, what caused that crack. Is there a structural issue that is causing it? Or, is it the result of a big OOPS! If it is structural, then the root cause should be addressed.
Could you zoom out a bit on those pictures? Is that the road side, or the curb side. It looks like a side window, is it? The crack does not seem to have separated much.

Assuming that there is no larger problem, then the solution is to grind the crack, from both the outside and the inside, (yes strip the Ensolite back) down to paper thin, at the crack to 3" or so back from the crack. Then, on both sides lay down fibreglass mat in strips 6" wide, then maybe 4", then 2". till the seam is thicker then the original. Then grind, and/or sand, smooth, especially on the outside. Then paint to match.

[Kenny in Ohio]

Darrel
I agree with David Tilston about determining the cause of the crack. I can only speak as a welder and have repaired metal tanks such as boilers, stacks and so forth. It is common practice and written in construction codes to radius the corners when cutting openings in any structural item. I see in the picture you added that the opening is cut with a sharp corner. This creates a "stress riser" in other words an the area that would most likely fail when stressed because in has a weak spot designed in it. There may not be anything wrong with your trailer simply prolonged vibration over time. Typically in metal you would radius the corners using a ratio of three to one an example would be 1" thick plate would use a 3" radius. I wouldn't think that would be good on such a thin piece of fiberglass but a any radius in your window cutout will certainly help.
To add to David's repair idea I would find the very end of the crack and drill a 1/8" hole to prevent the crack from progressing and then fill with the repair material as described by David.
Good Luck

[Bob Miller]

I think that Kenny hit the nail on the head as to the cause. A square corner is like a magnet for cracks, radiused (?) corners distribute stress, sharp corners concentrate stress, which is why we drill a hole to stop cracks.

And as Deryk suggested, it's not a quick-fix problem, it's a major repair problem. Do it right the first time or it will come back.

BTW: I know a certain FGRV reseller that loved the tape-over-a-hole/crack/damage and then spray paint method of repair. It got them hauled into small claims court where a buyer won a considerable settlement.

[parmtree]

Can't tell you all how appreciative I am for everyone's collective feedback. Looks like I have my work cut out for me. Thank you all for putting the time in to help me. I'll let you know how it works out.

[Paul O.]

Yes, Kenny has it right. If I had to do it I would also drill a hole (could be bigger than 1/8 inch since it will be glassed over) at the end of the existing crack before repairing. I would also make the corner of the opening with a radius as big as possible and lay the glass mat so some fibers follow the outline. Hopefully this was the highest stressed corner of the opening and the others are OK. Look at the other corners once you have the window out and create a radius in each and smooth it out with sandpaper.
The crack was the result of stress concentration and fatigue.
Never fly an airplane with square windows! Luckily, nobody is stupid enough to make those any more. De Havilland Comet was a beautiful plane, but had square(ish) windows... Look it up, here are pictures:
https://www.google.com/search?q=come...=1058#imgdii=_

[Darwin Maring]

Stop Drill at the end of the crack to prevent it from going further.

[David Tilston]

Yes, drill a hole at the end of the crack, then grind around the hole, till it is paper thin, just like the rest of the crack, before you start filling back in with polyester resin and glass.

As for adding a radius to that corner, it might be hard to get the window back in if the radius is too large. This is an old Trillium, with jalousie windows after all.

[Darwin Maring]

It would be really nice if you could get something on the inside of the crack (Back Side and glued with at least 1 inch overlap on both sides of the crack)

[deryk]

The only fix is as suggested already...open the crack up a bit with a dremel, grind/sand the surrounding area down around it and lay up a few layers of cloth and epoxy....let it cure then sand and fair it out and paint it.... things should be done right and since its at the corner of a window frame its likely to happen again if it isn't done right.

[parmtree]

Getting together my equipment list....
What type of grinding wheel would I need for this job?
For the fiberglass cloth and epoxy, if I went into a boat repair shop, do I need to be specific on what I ask for?

[KevinScamps]

Don't use epoxy if you are going to gel coat. You can get away with it, but better to use polyester resin rather than epoxy since gel coat is polyester resin and so is the rest of your camper.

It should be noted that I have done all my repairs using epoxy and then gel coat over it. I had a hell of time with amine blush because I was working in the winter in my garage. It won't be such a problem in the summer, but I would still use polyester resin, bondo, etc. if I had to do it over again.

[stevebaz]

If this were mine I would clean the back side and use woven fiberglass 12" wide running almost a foot past where you think the end of the crack is. putting a large repair past the crack will move the stress point way beyound the fracture and stabilize the area. I would use probably 2 layers of 6 to 10 oz fabric. I would not thin or repair the crack on the out side unless you have too. Once you open that can of worms the trailer will look like crap until you get the whole thing redone. The repair isnt complete until you grind the outside and finish with more glass but that doesn't mean the repair is failing its just less ugly. There is a reason this shell cracked eithor the floor is failing or the inner support for the roof has had issues or something allowed this area to flex uncontrolled. I would continue to look for the cause and effect.

[David Tilston]

All I use is polyester resin. Purchased by the pint, or gallon at Princess Auto. They sell glass mat as well.
1 Litre Fibreglass Resin | Princess Auto
8 sq. ft Fibreglass Mat | Princess Auto

I use two different grinder disks, for gouging, I use a flapper disk:
Pro.Point 4-1/2 in. Flap Disc | Princess Auto

And for smoothing, a flat disk with a backing pad:
4-1/2 in. Premium Sanding Disc Backing Pad | Princess Auto

The grinder, if you don't already have one should not be anything special. Fibreglass grinds off fast! Princess Auto has one on sale for $30.
http://www.princessauto.com/pal/Angl...nder/8336166.p

[parmtree]

I think I'm ready to go. Really appreciate all the help.

[D White]

That crack could only be caused by weight on the top like getting on the roof or snow...repair it with polyester fiberglass mat and resin ONLY. As I have said many times before...DON"T USE EPOXY...nothing sticks to cured epoxy except epoxy...so ANY conventional finishing materials won't stick. Also, drilling a hole at the end of a crack in fiberglass to stop the cracking is not correct for fiberglass, only plastic...don't do it...doesn't help...the fiberglass repairs will be strong and hold if done correctly with fiberglass materials...easy to do, cheaper, and has worked for the last 60 plus years...no need to try to reinvent the wheel or fix a problem that isn't there...Dave

[KevinScamps]

I wouldn't go nuts sanding on the outside. First remove any tape residue, the just open the crack up on the outside since the gel coat is super thick and you want to get it all the way into the crack. Then paint some gel coat into the crack and cover with the right plastic. That will make the surface pretty much smooth and limit the amount of sanding required. The business side of the repair is the back with the cloth.

[David Tilston]

Sorry Kevin,

The cloth should be on both the front and back. It is necessary to grind off the gel coat, and thin the fibreglass to paper thin at the crack and feather it to full thickness 3" on either side of the crack. Grind half the thickness from the outside, and half from the inside. Then fill back in with resin and mat. Grind / sand the outside smooth. Then paint.

[KevinScamps]

David,

I don't let the perfect get in the way of the good enough. By the time you have a couple of layers of cloth on the back and filled up the crack with resin, that area will be stronger and stiffer than the rest of the camper. I agree, that technically you are entirely correct, but as others have pointed at, once you start putting cloth on the outside of the camper you create a big mess that creates a lot more cleanup work.