re-gelcoating - how much of old needs to be off?

[ktm_2000]

Hi All,

I was originally going to paint my transom but I found a product from System3 which advertises that it can go over epoxy based repairs and allow you to then coat with gelcoat if you sand and apply gelcoat within 48 hours of application. So my new goal was to just do the bump-out portion of the transom where the twin outdrive holes had been sealed in.

My Bertram like many of its era have gelcoat issues where the gelcoat has loads of tiny cracks which do not seem to be related to any stress or fractures as they are pretty consistent and are over large areas.

The enemy of good enough being better I was considering gelcoating the whole transom.

Last night I gave the bump out portion a good sanding and while I was at it I sanded the gelcoat on the rest of the transom above the waterline. I took the area down a fair amount but there is still gelcoat remaining. I am assuming that if I did straight gelcoat over those areas the gelcoat would eventually crack in the same locations.

Questions:

Could I just sand the gelcoat down to the point that it is no longer opaque so that it still seals up any imperfections in the glass - aka avoid filling and fairing? I am assuming that it would eventually crack but the more I sanded the less likely or longer until it did crack

or

Should I coat the whole transom in 2 coats of the tie coat epoxy with the thought that the epoxy could be a bit more flexible and not print through previous cracks?

or

Am I pumping a dry well and need to do this right and take all of the gelcoat off and do multiple coats of high build primer, then paint?


I don't need this boat to be a show boat - I do have the transom with easy access right now and no signs of getting a motor so I've got a little time on my hands.

Your thoughts?

[Tony Meola]

I have always been told that the only way to get rid of the cracks was to get rid of all the gel coat.

Then I saw this You Tube video.

https://www.youtube.com/watch?v=tisqPlnTN34

Might be an easier option for you. Sand it to get a bite, then put a layer of cloth over it.

[ktm_2000]

Tony,

That may be a solution for when I do the hull sides some time after I get a motor, I am thinking more down the line of sanding as much off as I can and or not doing the rest of the transom.

[CamB25]

It's not hard to remove the gel coat and build up from the glass. 36 grit grit disk or flapper on your high speed grinder will vaporize the gelcoat. grind-fair-block-prime-block-paint

[Ironworker]

With the quality of paint these days, I'd have a hard time fooling with gelcoat. Paint it.

[ktm_2000]

over my years I've tried a few paints and none have been all that good for too long. I emphasize too long....

In my experience if one wants to paint every 3-4 years, use a single part paint. If you want to paint every 5-6 years , use a 2 part paint. Gelcoated surfaces tend to stay in better shape much longer. Any one of the options will show the cracks in the original gelcoat if those are not taken care of in advance.

I went out over lunch and bought a bunch of 80 grit 6" da pads and will sand down the transom as there isn't a huge amount of area left to clear.

[ktm_2000]

The enemy of good enough is better

https://photos.app.goo.gl/y7avJC7cVbv8xSzV7

1.5hrs of labor to sand the 2 side portions - no way would I do this for the whole hull.

[John F.]

Sorry, but I couldn't get the pic. to come up. What did you decide to do here? I'm really interested because my B20 has lots of the gelcoat cracks--looks like shattered safety glass--all over the bottom and extending up where the chine is submerged. I keep her at my dock. The hull sides were painted about 15 years ago and look barely OK, but the boat is ready for a rebuild. I'm pretty sure that the stringers are rotten, and deck is water logged, and she needs a bottom job and hull/topsides paint. So, I'm really interested what you're doing

[ktm_2000]

John,

I had a good portion of my transom already worked on, I had filled in the bump out where the 2 outdrives were and made a motor well. so @60% needed to be dealt with at a minimum. My thought process is that while the boat is under repair and I still have no ETA on when I am getting a motor I should try to redo the surface of the transom while it is easy to get at.

It took me 1.5 hrs to sand out the gelcoat on the transom side portions. I mostly used a grinder and a Norton 60 grit flap disk and was somewhat taking it easy because I did not want to make a huge fairing mess for myself. Even still I will have to fair out the surface and am planning at least 2 passes of fairing compound with sanding in between.

I am going to gelcoat the entire area - the thought is 3 passes, 2 with no wax gelcoat, 3rd with waxed gelcoat. All coats to be thinned 10-15% with styrene and rolled on. Once done I expect orange peel and will wet sand by hand with 400, 800, then compound with 3m Finesse it.

As for doing the hull sides - that is excessive... and not in the cards anytime soon for me. When I do eventually take it on, I think I would go down the path of the link that Tony presented and would do a relatively fast sand with 80 grit, Laminate 1 layer of 10oz cloth, come back with a 2nd coat of resin to fill as much of the weave as possible, then do the dreadful fairing and longboarding plus a similar gelcoating process as done on the transom.

Like I said, I have no plans for doing that anytime soon, my hull sides have plenty of the spider cracks and it has been that way since I've owned the boat in 2003 - there not changing much and don't look all that bad from 10' away so it is not high on my bucket list.

[Tony Meola]

John

If the hull is showing stress cracks below the water line, I would get it sand blasted. That will open up a world of sins. But then you could just give it a coat of Interprotect fairing compound, smooth it out then coat it with 3 to 5 coats of interprotect.

https://www.interlux.com/en/us/boat-pai ... /watertite

https://www.interlux.com/en/us/boat-pai ... cing-putty

[Raybo Marine NY]

If your plan is to sand and polish the gelcoat 3 coats will not be enough

[ktm_2000]

agreeing with Rabo I put 4 coats of gelcoat rolled on saturday and let it cure out sunday.

Let the fun begin Lets just say the orange peel even with thinning out the gelcoat is fairly bad. I did a small section with 400 wet and knocked down the worst of it but I may have to use a more course paper for the initial. I will break out the buffer and compound and see what the small section looks like first.

[ktm_2000]

an update, I ended up sanding with the transom 220 grit on a small 5" random orbital sander and then moved over to 400 wet by hand and sanded till my arms wanted to fall off. There is one area where the sanding wore through the gelcoat and it is in the upper corner of the transom so I will touch it up when I gelcoat the next area.

I am quite happy with how the transom looks and I will do a light compounding tomorrow, hopefully no other burn through spots appear.