Stump strike repair (Was: Oh, Glassman...)

[Speedling]

Yes, that was the object. I may have missed one or two small spots, I guess. But tomorrow when I clean up the epoxy, I will have a chance to double check those.

That, and, I strongly believe that the bottom of the boat was put on the bottom for a reason. And it wasn't so everyone could inspect it.

My bottom has a repair but no one would know except that i tell them!
And it's not even red like the hull!

 

[CrankyGypsy]

like @ClemsonTiger , I don't want to be the guy that ruins the party, hurts feelings, and/or regrets throwing his opinion out there. but here goes...

unless you are only looking to get through the weekend and re-fix it later, the repair you are currently doing is a poor solution: 1) damaged glass has to be completely removed and the repair area actually extends further out. you can track the edge of damage by wiping with acetone - it will "highlight" the cracks. 2) gelcoat (poly based) doesn't always stick to epoxy. to me, that's too big of a risk. besides, epoxy is overkill ...and I usually like overkill.

here is an in-depth thread for the FRP newbie:
https://jetboaters.net/threads/how-to-beginner-frp-repair-in-the-driveway.8184/

 

[tdonoughue]

Thanks, @CrankyGypsy . I know everyone is trying to help and no one is trying to be a wet blanket. I posted here to get some advice and the benefit of your experience. I appreciate your risking giving it. Absolutely no hurt feeling here; only gratitude.

I absolutely accept that I may be messing the whole thing up here. However, a few factors I consider: a) I am only into this for 2 hours worth of work and about $13 in materials, b) as far as I can figure, if I mess up this repair, I (or someone I hire) will need to take it all off and remove the fiberglass, which is basically the alternative anyway, so I am doing no harm c) even if I do something temporary, if I can get about a month or 1.5 months out of it, everything else can be cleaned up on the off season, d) I might even learn something, and e) I already started (for good or ill), so I may as well finish. I am also acutely aware that the boat cannot go in the water as it is.

When we last left our intrepid Spaceman Spiff, his craft had been shot by Vogons and he was trying to fashion a repair to get off of XJ-12 in time for his brother to get there for the weekend. Today, I started by re-evaluating the stripped area. Pretty happy with the spots I epoxied (there were basically 3 small spots)--it smoothed things out. But there were still some edges on the gelcoat that I had not been able to get well-feathered with the grinder. I broke out the Dremel tool with a hyperbolic cone sanding bit and completed the feathering, catching some of the spots I missed along the way. I also hit on the epoxied spots to remove the surface epoxy and expose glass. Basically cleaned the whole thing up. Went over the whole area and pushed on each spot to make sure that nothing was soft or squishy or giving way.

Then, I flushed thoroughly with isopropyl alcohol to get off all of the dust and to evaporate as much water as possible (that is what the drips are):



I should hasten to add that, while cleaning up, I did find that @CrankyGypsy was exactly right (though I did not read his post until I got home). I found several areas of spider cracks around the repair area, particularly on that bottom face. The major ones I expanded the repair area to include them entirely. A couple of the minor ones I Dremeled out a little trench along them. Yes, I probably missed some; I will need to try the acetone trick to see how badly I did.

Once all dried and heated, I mixed up my gelcoat. This time I went and bought some flux brushes. I was very pleased with how they worked with the thickened gelcoat. Previous repairs I used a plastic Bondo tool. That worked ok, but was a bit large. It wound up spreading the stuff a lot when I really wanted to just lump it in one area. These little brushes were the ticket, I think. Basically, I could use the heavy bristles to dab the gelcoat into the repair area to make sure I had good contact to the glass and no air bubbles. And I didn't get the gelcoat everywhere. Covered with Saran Wrap and...


I am sure that it will not be as smooth as when I used the hard plastic cover, but I found that the hard plastic is really better only on flat surfaces. It does not bend around corners very well.

We will see tomorrow what it looks like and go from there. Hopefully it will at least be serviceable. Thanks everyone for the continued help and opinions.

 

[Ronnie]

Nice work @tdonoughue .

 

[buckbuck]

Watch out for those Vogons. They are a nasty species.

 

[tdonoughue]

Lessee... This would be day 3 of repair (well, not full days). Brother got here late last weekend, so we did not wind up going out. Good thing I hurried. So, today was the next day I got up to work on the boat. Removed the Saran Wrap and everything was cured (of course--after a week). So I went to sanding.

I only did the 320 wet sand with block. I still had a pretty high spot of glass apparently, because it poked through almost immediately. So I sanded everything else flush to the undamaged area, then brought the grinder back out to take down that epoxy/glass ridge just a little bit more. Have I mentioned I hate sanding? I hate sanding. But it went fine. Then it looked like this:


So, I had taken some professional advice from a real fiberglass pro friend. He advised the Preval sprayer and to use the paste gelcoat, but thin it out with acetone. Never did that before. But, off I went. So I mixed up the gelcoat with the hardener as normal (used 11 drops rather than 10, in case the thinning affected it). Then I began carefully thinning. I had an eyedropper and added 2ml at a time--up to 8ml for the half a jar. I removed the little filter from the straw for the sprayer. I carefully strained it into the container for the sprayer--only to find it barely came up to the straw when I put the top on. Uho.

I tried it, but no dice. Not enough to spray. So, I took off the sprayer top and unceremoniously dumped some more acetone into the mix, covered with one of the covers, and shook it around. Put the sprayer back onto the reservoir and I was in business. It really did spray very nicely, but I do wish that I had had more material with which to work. I still ran out rather quickly, but I had enough to get a good coat on the whole area.

Next, I took some PVA mold release, cleaned out the sprayer well with acetone, dried it all, and put in the PVA. See, same pro friend clued me in that I shouldn't cover with Saran Wrap--instead use this stuff to spray over the wet gelcoat. It will dry, leaving a coating on top which is airproof, which then will cure the gelcoat. So, armed with this knowledge, I sprayed the PVA (full strength) onto the area. Now I have:

(the repair area is at the very left side of the second picture, as I was looking practically into the sun and need to frame it that way or it would darken the whole pic).

Anyway, I think this is great progress. I still have lots of divots there to fill (not sure if I will do the paste or the spray again--but now I know how to do both!). But at least when this dries I am pretty sure the boat is runnable. By the way, the PVA will come off with a Scotch pad, I am told.

Oh, pro tip: remember that PVA stuff? Don't try to clean it up with acetone. If you pour in acetone it immediately gels. Left a nice thin, strandy film in my sprayer when I poured it in. Very much a mess:

This is what I fished out of the reservoir and dumped onto the nearby groundcover. Yuck. Almost ruined that sprayer, I am sure (but at $5, not all that bad). Fortunately, I saved it.

End of this report.

*Only one computer was damaged in the making of this report. Dropped my Surface Pro. Glass pieces everywhere... Don't all PETC on me. People for the Ethical Treatment of Computers, of course.

 

[tdonoughue]

Report number... Um.... Next:

So, got back to the boat tonight to take off the PVA mold release and get the next coat of gelcoat on the boat. Warning in advance--no pics on this post. Ran out of time.

So, to get the PVA off, a Scotch Brite pad. Had some old ones, so went to work. On the smooth parts, it worked like a charm, as long as I went slowly. When I went too quickly, it seemed to almost melt the pieces back into the surface. It does require some elbow grease. And, had I had a much smoother surface, I would have had it done in about 15 minutes. Of course, I did not--mine has all sorts of pits. I didn't want to put more gelcoat on over the PVA release agent in the pits (that just could not end well). So I was scrubbing with the Scotch Brite pad, then broke out a toothbrush, then added acetone to the toothbrush. Finally I think I got it all. Cleaned it up with a paper towel soaked in acetone and it looks pretty good. But it took me 60-90 minutes to get all the spots of PVA off.

More pro tips if you try this:
1) Use a new Scotch Brite pad. Mine were old and brittle and made a real mess.
2) If you do it this way, best with a smooth surface. Otherwise, I think I would go with the plastic, maybe. I should note, the smooth surfaces this worked VERY well--they are still all smooth and ready for sanding/buffing.
3) Might try a stiff nylon bristle brush if you have contours left in your gelcoat. Wish I had had one with me rather than just the toothbrush.

Next edition: he cleans up those pits with the paste gelcoat.

 

[Glassman]

Can't wait to see the final result

 

[tdonoughue]

So, I started today with a light brush with a soft metal brush, to make sure I had all the PVA off:

You can see the pits.

So I mixed up the paste and went to work. I went slower this time and worked the gelcoat with a flexible metal scraper to spread the goo. The edge was the trickiest. Now I have:

And...


Then I sprayed more PVA and headed home happy. Much closer.