Made a discovery while working on boat. Help!

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smidge
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Made a discovery while working on boat. Help!

Post by smidge » 22 Mar 2016, 16:55

So the last few days I have been working on my boat and getting it ready for trout season. I rebucked all the rivets on the seams, but the seal inside must be damaged be a use it still Leaked. I sealed the seams with gflex epoxy (didn't have 60 bucks and an hour to drive and get gluvit). It worked great and the seams are not leaking anymore. YAY! I also had a few rivets on the bottom that were leaking but not much, so upon cleaning them up to get ready for the epoxy I noticed the bottom is starting to pit (I previously thought this was just salt or a bad paint job). For now I filled the bad one with epoxy whike I epoxied the rest of the rivets.

My question is, what can I do to prevent this from getting any worse?

And In guessing the gflex has no UV protectant in it, what should I use to paint over this? I was thinking maybe just rattle can clear coat? I have it on the outside and inside seams.

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DaleH
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Made a discovery while working on boat. Help!

Post by DaleH » 22 Mar 2016, 17:48

Only very few - and limited use at that - epoxies have any UV inhibitors in it. Epoxy must be painted over for UV protection.

Are you using this hull in saltwater? Is it moored or just transient use? But WOW, it seems like we're seeing 'pits' on surfaces that aren't anywhere near a seam or rivet. Did you coat those areas?

Hate to say it, but unprotected aluminum in the salt is just asking for trouble. I don't see anyway around it but prepping-to-bright the tin and etching with a good 2-part zinc chromate primer. Then sealing if/as needed. You might also want to be looking into Steel Flex.

That said, I bought an old '78 12' tinny that was always used as a skiff in the salt. It was prepped and steel flex'd many years ago and its still sound. In 2 spots that look just like yours, they added what appears to be gray colored 3M 5200, but that isn't made in gray. Maybe it was a Silka-flex product?

Regardless, it is still somewhat hard, yet still pliable and since it was added over properly primed/etched aluminum, those 2 repair areas are still sound and there is no adverse corrosive attacks in those areas.
#1) 1st tin rebuild, 18' Lund http://forum.tinboats.net/viewtopic.php?f=21&t=36583
#2) 25' Parker refurb from EMPTY hull http://www.classicparker.com/phpBB3/vie ... p?f=15&t=6
#3) 16' V-tin rebuild http://forum.tinboats.net/viewtopic.php?f=21&t=36465
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#5) 16' Starcraft entirely NEW Transom Skins http://forum.tinboats.net/viewtopic.php?f=3&t=37548

smidge
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Joined: 20 Sep 2015, 23:11

Made a discovery while working on boat. Help!

Post by smidge » 22 Mar 2016, 19:27

I do not plan on using it in salt water, but i do live near the beach and may get it in the ocean someday. but not now.

This is how i bought the boat, it had the coating already on the bottom you can scroll through my history and view previous posts.

Where you see bare aluminum was where i prepped for epoxy, What i did was took a wire brush and removed whatever was there down to bare aluminum, and then i applied the epoxy. What should i use to paint over the epoxy? its just a small strip all the way down length of boat on the seam inside/out

Also it will not be moored anywhere. will be taken home daily besides maybe being in the water a week if i go for a long trip with it. fresh water that is

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richg99
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Made a discovery while working on boat. Help!

Post by richg99 » 23 Mar 2016, 11:41

If your epoxy patch is on the bottom of the boat, I don't see a need for UV protection there. It will never see sunlight.

I do wonder what caused the pitting? As you may have noticed if you've read this site at all, using non-treated lumber is strongly recommended for bunks and any other items attached to the hull. It is possible that the bunks on many boats were made of Treated lumber. Their chemicals leak through the carpet and start a reaction with the aluminum boat, whether it was painted or not.

Do the pitted areas line up with where the bunks contact the boat?

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Ictalurus
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Made a discovery while working on boat. Help!

Post by Ictalurus » 23 Mar 2016, 12:13

richg99 wrote:Do the pitted areas line up with where the bunks contact the boat?
My thoughts also.

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DaleH
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Made a discovery while working on boat. Help!

Post by DaleH » 23 Mar 2016, 13:25

If the pits are under the epoxy coating you applied, then I say the surface wasn't prepped correctly and some chemical reaction is taking place ...

A good prep for aluminum, especially if the boat was used in salt waters, is to mix up a solution of 1-gallon warm water with 1-cup of white vinegar and tiny splash of dish soap - just enough to make suds.
#1) 1st tin rebuild, 18' Lund http://forum.tinboats.net/viewtopic.php?f=21&t=36583
#2) 25' Parker refurb from EMPTY hull http://www.classicparker.com/phpBB3/vie ... p?f=15&t=6
#3) 16' V-tin rebuild http://forum.tinboats.net/viewtopic.php?f=21&t=36465
#4 Procraft SV14
#5) 16' Starcraft entirely NEW Transom Skins http://forum.tinboats.net/viewtopic.php?f=3&t=37548

smidge
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Made a discovery while working on boat. Help!

Post by smidge » 23 Mar 2016, 17:23

OK so let me clarify. I bought the boat with bottom paint and epoxy already on it. It looked like the epoxy was applied over the bottom paint by previous owner. I took a wire wheel and got it down to bare metal, then sanded with 80 grit before applying epoxy.

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jigngrub
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Made a discovery while working on boat. Help!

Post by jigngrub » 27 Mar 2016, 02:12

Looks like galvanic corrosion to me, trapped water that has sat and the oxygen has been depleted. As the oxygen depletes the water becomes acidic and pits/corrodes the aluminum.

The best fix is to prep, fill the pitting with a epoxy type filler like JB Weld marine or Loc-tite Marine epoxy, prime with a self etching primer and paint with a quality marine coating/paint.

Have you checked your transom plywood? Chances are you have the same pitting and corrosion between the back of the plywood and the inside of the hull. Use the same fix as described above to repair that mess too.
Rum, wenches, and song... just another day on my boat.

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Captain Ahab
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Made a discovery while working on boat. Help!

Post by Captain Ahab » 27 Mar 2016, 07:55

smidge wrote:OK so let me clarify. I bought the boat with bottom paint and epoxy already on it. It looked like the epoxy was applied over the bottom paint by previous owner. I took a wire wheel and got it down to bare metal, then sanded with 80 grit before applying epoxy.

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BOTTOM PAINT? This likely means the boat was stored in the water and likely salt water at that.

I wonder if the previous owner used bottom paint made for aluminum boats???????


Clean up the areas with vinegar and add some epoxy if the pits look really bad. UV is not going to hurt aluminum - just rinse after any SW exposure and watch out for any dissimilar metals - like steel!
Trying to Fish as often as Jim works :LOL2:

sdm111
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Made a discovery while working on boat. Help!

Post by sdm111 » 27 Mar 2016, 08:15

Looks like a good candidate for steel flex epoxy. I did mine not long ago for the same reason. It's not.easy to.work with though it has the viscosity almost of honey and in hindsight I would have trowled it on with the boat upside down and a brush to feather the edges. Worked great though the bottom is now smooth like glass and very much sealed.

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msumoose
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Made a discovery while working on boat. Help!

Post by msumoose » 01 Apr 2016, 12:30

If it had true "bottom paint" on it, I would imagine that it is galvanic corrosion. Many bottom paints for saltwater boats use copper as an algaecide to prevent bottom fouling. That on the aluminum is recipe for disaster.

As to how to help you...I have no clue. Sorry.
MSUmoose

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