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Old 07-12-2022, 21:31   #1
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Removing bottom paint and saving my marriage

We hauled our Tayana 37 for a quick in and out insurance survey. We had to renew and the insurance company insisted on a haulout.

While out, I noticed there was some sort of crack in the fibreglass under the bottom paint, just behind the prop. When I pressed it with my finger, water spurted out. A crack about a metre long showed itself in the bottom paint. Scary.

Not sure I understand how our boat is constructed, but the layer of fiberglass that flexes below the crack seems to be only about 5mm or 1/4" thick, but perhaps it's an illusion created by how easy it was to press it in.

The surveyor is a sweet guy. He did not notice the crack but did recommend the replacement of a prop anode. Luckily we had one ready.

Anyway, we went back in and began preparing to repair the hull. Plan is to remove the bottom paint, assess the situation, drain, dry and glass over the crack.

I want to do it as soon as possible.

It's complicated, but my loving wife has rented a cottage out east where we will have a family reunion of sorts and she wants me there, not here mucking about on the boat. To hell with my happiness.

So time is short. Plan is to remove the bottom paint, and while out east let the hull drain and dry, even if that means drilling holes into the fibreglass to drain.

A local sandblasting company says it can be done in two days, they quoted $7,500. I passed. Even if it took me a week to scrape the bottom, I've never earned $1,000 a day.

But I need a quick way to remove bottom paint. I'm not afraid of work. Online, I've found some people use chemical softeners followed by a vacuum scraper. Has anyone cleaned their bottom this way?

Any suggestions, chemicals, scrapers or other solutions, would be much appreciated.

My marriage depends on it.
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Old 07-12-2022, 22:01   #2
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Re: Removing bottom paint and saving my marriage

I would be surprised if you can scrape the bottom paint by yourself in a week. Maybe 4. Then consider the additional cost of time in the yard.

I've researched the chemical thing, and a friend did it and thought it worked well. But it was still a couple weeks, and a lot of work. Paint the hull with the chemical. Then apply plastic film to it so it won't dry out. Then tent the boat and use a heater to get it hot and let it sit a couple days. Then scape, and it comes of easy instead of difficult if you hadn't used the chemical.

The fast ways are soda blasting, or hiring a few people to attack it with sanders. A few people with sanders could strip it in a few days, but then you will need to address any damage sanding causes.

I would consider just hauling out, and let it dry without removing the paint. Then deal with the work/expense when you get back. If nothing else, you won't have your wife telling everyone at the family event how much money you just spent.
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Old 07-12-2022, 23:29   #3
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Re: Removing bottom paint and saving my marriage

Sounds like you have a cored hull. Expect to open it up and remove the damaged core. Replace with balsa or a synthetic option then reskin with fiberglass……. Big job.

To remove bottom paint I was told lye mixed with lime and water into a paste and roll it on. Then power wash and it comes right off. Inexpensive and effective.

Good luck!
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Old 08-12-2022, 00:02   #4
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Re: Removing bottom paint and saving my marriage

@foojin:

Something serious is wrong there.

If you have a mate with a big side yard, maybe you can arrange to crane it in there. You will, I'm afraid, have a long saga ahead of you. Best will be to store the boat on the hard somewhere free or nearly free.

The first thing to do is find out what is wrong, and this will mean grinding back where the crack is till you find sound fiberglass.

Once you figure out what is wrong, then you can start planning to fix it all.

Go to the family reunion, and let your subconscious mind work on it. Be very nice to everyone. (Consider it a deposit on some help later on.)

Take pictures of what you find, it helps to imagine.... What you've described could be a little delamination, and maybe some separation between layers of what is still a sound hull, or it could be something requiring a more intensive fix. Worrying is a waste of time. You'll get the data you need in due course.

Sorry for your troubles.

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Old 08-12-2022, 00:57   #5
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Re: Removing bottom paint and saving my marriage

Do you need to remove the paint on the entire bottom or just around the repair? I'm guessing $7500 presumed the entire bottom.

How hard it is to remove bottom paint depends on the type. Ablative is much easier. Certainly if you just do a 1 meter by 12 meter area, it should be a lot less (or DIY).

A quick look online shows a solid glass hull (not cored). Also, it appears to be an integrated keel (not bolted on).

This should make repairs straight forward (assuming it's not some crazy deep crack where the keel is ready to fall off but that's unlikely). Remove bottom paint around the crack and then grind back the fiberglass until you get to a clean non-cracked surface. Then build back up.

Assuming you don't find something wild, any decent fiberglass guy should be able to fix it without it becoming a major production.
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Old 08-12-2022, 01:30   #6
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Re: Removing bottom paint and saving my marriage

I have always had problems sanding bottom paint with discs. I find that the discs get clogged really quickly, especially if there is any water in the glass, as you have in the damaged area.

So I would use a 7 inch sander polisher with some 40 or 28 grit. Test how to use it on something before you apply it to the boat. Then also have a large wire wheel mounted on a grinder too, for when you find it clogging.

I would not do a job like this with a time deadline. Hopefully you have a quick fix, but I wonder, why is the glass lifting? Why is there delamination, even of a solid laminate. Such questions are worrying and you don't know what you will find.

Remove anitfoul only over the affected area, that should reduce the time a lot. Then grind out the glass until you get good stuff. Then feather the edges really well. If the problem is, let's say, 800mm long, 100mm wide and 5 mm deep, then once I have finished grinding I should have a shallow vee groove about 1000mm long, about 500mm wide and probably 6-7mm deep. Then lay up nice glass and resin, I would use epoxy if it was mine because I love its excellent adhesion and stitched fabrics like double bias. Layup new glass, each edge stepped in by about 50mm. Then grind smooth, fair with microballoons and cover with epoxy and then epoxy primer. Then rubber antifoul primer.

Some may argue for poly but it is up to you to decide what you will be doing with the boat later on. I don't see the point of using poly for secondary bonding if the area will not be laminated on again.

cheers

Phil
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Old 08-12-2022, 02:15   #7
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Re: Removing bottom paint and saving my marriage

FJ, I used International's paint remover once on a 24ft rib on my driveway as it was a trailered boat.

I did it in the summer and despite covering the thick wall paper glue like substance with cling film, it seemed to dry too quickly and needed to be re-applied. It took 25L for 24ft and lots of scraping once softened. Despite putting down plastic sheeting it went everywhere. The tarmac drive eventually recovered after a year and my hair grew back.

It wasn't a great experience, but I don't know of an easier DIY solution. Scraping with a multi tool and then sanding would take several weeks.

That price sounds way too much, in comparison 31ft of hull would cost 700-1000 in the UK with sheeting and disposal assuming the boat is out of the water.

How bad is the rest? could you just do a patch where the crack is, say 2 metre square?
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Old 08-12-2022, 03:34   #8
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Re: Removing bottom paint and saving my marriage

Invest in a Festool Rotex with vaccuum, and sand it all yourself with very little mess, and save thousands over the course of many bottom jobs.

In the zone of the crack, I wouldn't even bother sanding off the antifoul first--just build a local tent, attack the crack with a grinder, and see what's down there. If the crack is all ground out, it will have a chance to dry while you're out east cavorting with the relations.
Ironically, I have to put my tools down to go WEST and see the relatives this winter.
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Old 08-12-2022, 04:08   #9
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Re: Removing bottom paint and saving my marriage

To determine the extend of the crack get a detail scraper with carbide blades and follow the cracked line.

https://www.leevalley.com/en-ca/shop...r?item=97K5210

My bottom sanding setup is a Festool vacuum 5" random orbit sander (DeWalt), Oneida Dust Deputy cyclone. I use Abranet sanding mesh discs by Mirka but similar ones are available at Home Depot.

Takes about 8 hours with long breaks in-between to do my CS27.
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Old 09-12-2022, 00:54   #10
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Re: Removing bottom paint and saving my marriage

Thanks to all for the great advice. I have to do research on some of the products suggested.

Yes, $7,500 was for the entire bottom below the waterline.

Pete, I also thought it was too much. Maybe a typo in the quote? It's not. There are complicating factors. The yard/marina where I usually haul has a strict policy about tenting and cleanup of any sanding, etc. The sandblaster in question is the only such company approved by this marina. I suppose I could get a better deal, but would have to find a different yard to do the work. I might anyway. They are not the cheapest yard.

Those who suggest I focus on the area of the crack... the bottom other than the crack doesn't look too bad. I suppose I could get away with just scraping a smaller area, but I've had a couple groundings and hit some logs over the years and think I just need to know what else is down there.

Benz, I have a Festool Rotex RO125 FEQ. It's a good sander, but I wonder if it's robust enough for this job. Which model do you use? Which vacuum?

5BTM, I have one of those scrapers. Thanks for reminding me. I'll dig it out. Dewalt has lots of sanders. Would you go with the same orbital again if it died tomorrow? Those Abranet discs look good. What grit do you use?

wholybee, do you remember the chemicals that you used? Hiring some young fellas might be a good idea. Maybe I will looking into renting a few vacuums.

NYSail, Will look into lye and lime. Sounds like it might eat the hull, solid or cored

vahalla360, thanks for the encouraging advice. I was hoping that was the case, but still not sleeping so well. (PS: are you the same Vahalla who lived in SE Asia and had a website with various nautical solutions? If so, cheers)
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Old 09-12-2022, 01:01   #11
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Re: Removing bottom paint and saving my marriage

Quote:
Originally Posted by foojin View Post
vahalla360, (PS: are you the same Vahalla who lived in SE Asia and had a website with various nautical solutions? If so, cheers)
Ironically, I'm in SE Asia at the moment but no must be someone else.
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Old 09-12-2022, 03:04   #12
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Re: Removing bottom paint and saving my marriage

FWIW: Some years ago I scraped 17 years of accumulated hard bottom paint from our previous boat, an old IOR one-tonner, 29 foot LWL, 12+ foot max beam. Using a 1 1/4 " carbide blade scraper, it took me around 50 hours of hard labor. I was required to clean up the resulting mess and it came up to nearly 400 lbs of old paint. A hard weeks work, but beats the hell out of 7500 bucks!

I won't advise on the repair, for it is out of my league, but in general fibreglass repairs are not too difficult... just messy and fraught with chemical hazards. Good luck with it!

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Old 09-12-2022, 04:11   #13
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Re: Removing bottom paint and saving my marriage

Quote:
Originally Posted by foojin View Post
Thanks to all for the great advice. I have to do research on some of the products suggested.

Yes, $7,500 was for the entire bottom below the waterline.

Pete, I also thought it was too much. Maybe a typo in the quote? It's not. There are complicating factors. The yard/marina where I usually haul has a strict policy about tenting and cleanup of any sanding, etc. The sandblaster in question is the only such company approved by this marina. I suppose I could get a better deal, but would have to find a different yard to do the work. I might anyway. They are not the cheapest yard.

Those who suggest I focus on the area of the crack... the bottom other than the crack doesn't look too bad. I suppose I could get away with just scraping a smaller area, but I've had a couple groundings and hit some logs over the years and think I just need to know what else is down there.

Benz, I have a Festool Rotex RO125 FEQ. It's a good sander, but I wonder if it's robust enough for this job. Which model do you use? Which vacuum?

5BTM, I have one of those scrapers. Thanks for reminding me. I'll dig it out. Dewalt has lots of sanders. Would you go with the same orbital again if it died tomorrow? Those Abranet discs look good. What grit do you use?

wholybee, do you remember the chemicals that you used? Hiring some young fellas might be a good idea. Maybe I will looking into renting a few vacuums.

NYSail, Will look into lye and lime. Sounds like it might eat the hull, solid or cored

vahalla360, thanks for the encouraging advice. I was hoping that was the case, but still not sleeping so well. (PS: are you the same Vahalla who lived in SE Asia and had a website with various nautical solutions? If so, cheers)
Sorry to quote the whole post just for the question that applies to me, which is about the Festool Rotex. You ask if it is robust enough: have you seen a better sander anywhere? I've never sanded cleaner and faster than with the Rotex 6". It's hooked into one of the smaller Festool vaccuums, so I can get it around the boat, and it is the most dust-free, efficient sander I've ever met in twenty years of sanding and grinding.
And if the paper's expensive, I'll just say that it lasts so much longer than the cheaper paper that it comes out more economical.
Just shove some 40-grit paper on the Rotex and get 'er done.
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Old 09-12-2022, 05:54   #14
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Re: Removing bottom paint and saving my marriage

"5BTM, I have one of those scrapers. Thanks for reminding me. I'll dig it out. Dewalt has lots of sanders. Would you go with the same orbital again if it died tomorrow? Those Abranet discs look good. What grit do you use?"

No, I would get a Bosch model GET75-5N.
Same principle as a Festool, but a lot cheaper.
However, you have a Rotex, so you are set for the paint removal.

80 was the coarsest grit I could get. I would have preferred a 60.
woodessence.com has coarser grits; 40 to 80.

I strongly recommend the Oneida cyclone.
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Old 09-12-2022, 06:43   #15
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Re: Removing bottom paint and saving my marriage

The large female mold is separated longitudinally for cleaning and mold preparation.The gelcoat is sprayed in and the first glass layer is laid up. The mold is then joined and all the remaining layups are done in the assembled mold

I found this in the net , seems to me its a split mold at the begining, the crack you found it behind the prop happen very often in a split mold construction...
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