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Old 14-11-2016, 10:31   #1
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When to strip bottom paint

I need advice on when you need to strip the bottom rather than just prepping and applying a new coat. I am a new owner of a 1978 O'day 30 and she needs some new paint before next season (New England waters). I was inspecting the current bottom and its definitely chipping and flaking off in pretty large pieces. Its clear that it has been painted over many many times. Especially the leading edge of the keel has large pieces separated and I'm not sure how to tell how far down the flakes are (just paint, gelcoat, etc.).

The rest of the story:
This is my first boat and the intent all along was only to have it for 2 years as a learner boat before stepping up to something larger/nicer. Having said that, this means that I don't want to invest any more money into the boat than I have to since I am planning on selling it after the season is done next year. Is it acceptable to just scrape/prep what is there and apply a new coat? Really I am asking at what point in time it has to come off or else you risk damaging the gelcoat and fiberglass?

Thanks in advance.

I found a lot of advice on how to strip/paint the bottoms, but not so much on when to do it. At my yard, all the bottom paint work must be done by their guys. I am afraid to get their opinion since they are almost certainly going to say I should fully strip and barrier coat it.
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Old 14-11-2016, 10:43   #2
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Re: When to strip bottom paint

If your only keeping it for 2 years.

Slop another coat on it and go sailing.

The fish really do not care what your bottom paint looks like.
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Old 14-11-2016, 11:06   #3
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Re: When to strip bottom paint

That's what I was hoping. As far as I can tell as long as you don't need repairs that drive a bottom strip, its ok to just put another coat on. Maybe losing a little performance over the years, but that doesn't matter to me.
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Old 14-11-2016, 11:22   #4
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Re: When to strip bottom paint

cnsutter:

Allow me to offer a different point of view, but not to say you can't do as Cotemar suggests.

If you have not already hauled for the winter [Sorry, I know that is a big "if", but your avatar doesn't give any idea of where your boat is located]*, then find a yard where you can take it back yourself. With a 30 footer, you can probably do it in a weekend. It's a lot of work, but with a re-done bottom, she should sell easier when you want to do that, she'll sail better minus the 500 lbs. of old paint, so she'll be more fun. All those chipped away places create small water swirlies and slow your boat. Herreshoff wrote that water doesn't like surprises, look at the shapes of his hulls. It is a big job, but you'll feel proud of yourself for having beat it into submission.

Ann

*If you choose to change your avatar to indicate the general location of the boat, it will help others tune their response to your location, making the answers more meaningful to you.
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Old 14-11-2016, 12:05   #5
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Re: When to strip bottom paint

Quote:
Originally Posted by Ann T. Cate View Post
With a 30 footer, you can probably do it in a weekend.
Sorry Ann, I burst out laughing when I read this.

The boat dates from the 70's, and we have no idea if he has 40 years of accumulated bottom paint, or 10, or 5.

I have a 40' boat. This past winter/spring I took off about 20 years of accumulated bottom paint. You can't sand it off...even with 30 grit it just burnishes, given the metal content. You can't grind it off unless you have MAD grinder skills. You have to scrape it off. It took me 40+ hours of backbreaking scraping to get down to the original barrier coat and sand. Another 10 hours to fill and fair gouges and repair a few very small blisters, another 8 hours total to apply four coats of barrier, another 3 hours to apply two coats of antifouling. And I've been doing this stuff since I could walk, and have all the skills and tools.

Even if he does it himself he's not going to get back the cost of materials when he sells. Barrier coat is not cheap.

It's not worth it for another knot or two of boat speed for a year.

Sutter, slap a few coats on it and go sailing.
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Old 14-11-2016, 12:29   #6
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Re: When to strip bottom paint

C,
I'm going to give you a suggestion that many might find "unusual" but it has proven to be an effective means to reduce labor on a questionable bottom. First, sand/fair/bevel all edges where the bottom exhibits paint failure so that it becomes a smooth surface. Then, lightly sand the rest of the bottom with 80 grit using a drywall sander. Launch the boat. Although your antifouling properties will be minimal, if at all, an aggressive monthly scrubbing of the hull will remove both accumulated growth and paint from your hull. If you own the boat for two years, a diver could easily remove a great deal of the paint film--perhaps enough so that when you're ready to sell your boat you can give it an aggressive sanding and a fresh coat of paint. It would help to know where you sail since if your boat is in the water for a year or more, the lionshare of your job will be done by the bottom cleaner. Good luck and safe sailing.
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Old 14-11-2016, 13:11   #7
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Re: When to strip bottom paint

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Originally Posted by Suijin View Post
Sorry Ann, I burst out laughing when I read this.

The boat dates from the 70's, and we have no idea if he has 40 years of accumulated bottom paint, or 10, or 5.

I have a 40' boat. This past winter/spring I took off about 20 years of accumulated bottom paint. You can't sand it off...even with 30 grit it just burnishes, given the metal content. You can't grind it off unless you have MAD grinder skills. You have to scrape it off. It took me 40+ hours of backbreaking scraping to get down to the original barrier coat and sand. Another 10 hours to fill and fair gouges and repair a few very small blisters, another 8 hours total to apply four coats of barrier, another 3 hours to apply two coats of antifouling. And I've been doing this stuff since I could walk, and have all the skills and tools.

Even if he does it himself he's not going to get back the cost of materials when he sells. Barrier coat is not cheap.

It's not worth it for another knot or two of boat speed for a year.

Sutter, slap a few coats on it and go sailing.
First, i agree with your final sentence...

When younger, I scraped 17 years worth of hard bottom paint off the hull of our previous boat, a beamy 36 footer with 29 foot LWL. I used a 1 1/4 inch wide carbide scraper, and it took 50 hours or very unpleasant labour to do it. The rules at the hardstand required me to sweep up and remove the scrapings, and this allowed me to roughly estimate the mass of removed paint, and it was about 400 pounds!

A job that I would not undertake again! But I suppose that Ann's statement about doing it (the scraping) in a week end might well be possible.

Minaret, who does have good grinding skills, says grinding is the way to go. He has mentioned what disks and grinders to use here on CF a couple of times, and it sounds good when he says it fast... but I keep seeing huge gouges appearing in my hull as I screw up (in my imagination)... I'm neither strong nor brave enough to attempt that route!

Jim
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Old 14-11-2016, 14:29   #8
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Re: When to strip bottom paint

You can apply an ablative over most hard bottom paints but not the reverse.

If you have a diver regularly clean the bottom then he, or she, can advise on the integrity of the bottom paint.

In reality you may have hot spots and the question is moot. Sand it back and replace.

It's best to plan to remove and replace your bottom paint if you're hauling.

For our Liberty 458 we've just moved from San Francisco Bay to the PNW. We took local advice in choosing our replacement bottom paint. It's also a job we outsource and we do everything else ourselves. The yard can do the job in less than two days. I would take much longer. My time is better spent elsewhere.



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Old 14-11-2016, 14:42   #9
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Re: When to strip bottom paint

I would defiantly strip it to the gel coat.

I'm a DIY person. And also frugal ( scotish for a cheap sob) the yard will charge you a fortune and not do as good of a job then you would do yourself.

I was in the same position. Bought a J24 and the bottom had 10+ years of bottom paint at some points almost 1/4 in thick. Boat was very slow and although you don't think it's important to have a faster boat, after you strip it and sail it next year you will be so happy you did.

I would sand down to the gel coat and apply a barrier coat then new bottom paint. It is painstaking and takes a long time but worth it. (rotary 4-5 in with 40 grit as the lowest)

I live in New England so in late feb I started. 2 hours every night. Took me 50 hours of sanding but once complete applying the barrier coat and bottom paint is easy. ( I didn't work every night so took me over a month)

If you take your time wear the proper protection. It will go fast. You plan is 2 years but in reality in 2 yrs you will start looking for a replacement and will wait another 2 before you actually have the new boat.

Just go for it You will be so happy You did. The performance alone is worth it.
Good luck and fair winds
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Old 14-11-2016, 14:43   #10
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Re: When to strip bottom paint

Quote:
Originally Posted by Jim Cate View Post
When younger, I scraped 17 years worth of hard bottom paint off the hull of our previous boat, a beamy 36 footer with 29 foot LWL. I used a 1 1/4 inch wide carbide scraper, and it took 50 hours or very unpleasant labour to do it. The rules at the hardstand required me to sweep up and remove the scrapings, and this allowed me to roughly estimate the mass of removed paint, and it was about 400 pounds!

A job that I would not undertake again! But I suppose that Ann's statement about doing it (the scraping) in a week end might well be possible.

Minaret, who does have good grinding skills, says grinding is the way to go. He has mentioned what disks and grinders to use here on CF a couple of times, and it sounds good when he says it fast... but I keep seeing huge gouges appearing in my hull as I screw up (in my imagination)... I'm neither strong nor brave enough to attempt that route!

Jim
LOL I had typed 50+ hours but then dialed it back for fear of hyperbole and because I did not in fact track how long it took to the hour. Suffice it to say, it took a loooong time.

I don't think it would be possible to do it in a weekend. There are only 24 hours in a weekend...and once you start, you're committed, for the most part. One weekend would stretch into two, then three. I suppose if you had some impressionable friends, some beer and music, and promises of glorious weekends of sailing as payment...

Also, when you haul and dig into a project like that, you want to do it right. You never know what you're going to find under that paint when you get it off, like failing "marine" bondo, failed keel/stub sealing...the list goes on and on . Glossing over that and dashing some barrier coat over it is disrespectful to the boat and downright dishonest to the next owner.

I know people who can grind a bottom down to the barrier coat...but it's not just a skill, it's an art. Your average first-timer would end up with a result that took more hours to fill and fair than it would have taken to just scrape in the first place.
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Old 15-11-2016, 08:31   #11
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Re: When to strip bottom paint

Simple ... take pride in your boat ... strip off the old on with the new.
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Old 15-11-2016, 08:33   #12
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Re: When to strip bottom paint

You might also want to look at this - Strippit Anti Fouling Remover, Paint Remover

Reactive Resins - a company based in Cornwall, UK - produce an antifoul remover. I haven't tried it yet, but intend to - albeit on a much smaller job.

Whether they will ship abroad, I don't know. But if they can produce this surely someone else is? It probably won't remove the need for manual labour, but if it does what it says it ought to make it a much quicker and easier job. And your boat should get a much better price when you sell if the hull looks tidy.
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Old 15-11-2016, 09:06   #13
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Re: When to strip bottom paint

The problem with the various stripping chemicals is they only tend to take a couple of layers off at a time. International Paints also have a version which I have used. Took 4 days to strip a 22ft rib sitting on a trailer and even though I used a plastic sheet underneath it took a year for the drive way to recover. The stripper stuff is like wall paper paste so needs to remain damp to work also you must not let it dry or it sets in lumps on the hull. Wall paper scrapers on a long pole help to remove the gloop.

Now during the winter would be the best time as it won't dry, whilst in the summer it will.

If it is chipping off and leaving smooth patches of GRP then you are in luck because it means the hull wasn't keyed before the first coat was applied so will make removal easier to get a good finish. Not sure a barrier coat of presumably epoxy is worth while on such an old hull. Plus you need the hull completely dry or blisters may form between the GRP surface and the epoxy. It would be better just to apply a thin layer of Primocon and then antifoul.



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Old 15-11-2016, 09:30   #14
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Re: When to strip bottom paint

Quote:
Originally Posted by Cotemar View Post
If your only keeping it for 2 years.
Slop another coat on it and go sailing.
The fish really do not care what your bottom paint looks like.
Totally agree with this advice. Obviously grind/scrap back flaky areas. But give it a good water blast when she comes out of the water. They always find the flaky spots.

I've been doing that with my boat for 14 years and no reduction in performance. Also the hull surface is still pretty good. I work on the theory that the more anti foul paint is on the boat the better the protection. And in reality it's actually not that much paint. We measure applied paint thickness in microns for a good reason.

The existing paint will be soft anti foul (she's a yacht).

Without meaning any disrespect to Ann I don't understand how she can possibly think stripping the paint is a weekend job. It will be a big old weekends job to just slap on the antifoul.

If you go down the paint removal road it will be a huge amount of work, and will go on for several weeks. And if you're paying people to do it for you! As well as time, this approach always uncovers other issues that need to be dealt with. There will be some blisters, gel coat abrasions etc that need to be carefully sorted and may need drying time. At the moment they're being nicely looked after by paint.

She'll need antifoul again every 12 months or so, so use this first opportunity to learn how to do the antifoul this time. Once you've got the boat out and painted her you'll have a really good idea of the actual hull you're dealing with. You'll have also learnt something about yourself. Are you a perfectionist, someone who's actually just into boat maintenance or do you just like sailing and near enough is good enough (certainly that's me). If you decide she does need the entire strip/repaint process then you'll have a year to prepare, save up and and get organised. And that decision will be based on the condition of the hull not on what a bunch of youtube videos and broken down old boaties tell you on the internet.

As an aside, except for the stupidly wealthy, antifouling is a job you do yourself. It feels great, and you get to hang out with a bunch of other boaties for a couple of days. And it's so easy. Plus it's important to get up close and personal with your hull from time to time. And in painting you're forced to look carefully all over.
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Old 15-11-2016, 14:47   #15
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Re: When to strip bottom paint

Quote:
Without meaning any disrespect to Ann I don't understand how she can possibly think stripping the paint is a weekend job. It will be a big old weekends job to just slap on the antifoul.
I think that Ann was extrapolating from the experience we had with our Standfast 36. As reported above, I hand scraped 17 years of hard bottom paint off her, and it took me a fairly accurately noted 50 hours to do so.

The O'Day 30 of the OP is quite a lot smaller boat, with appropriately less wetted area. Further, the OP has stated that large areas of the antifouling have spontaneously fallen off which also reduces the work load. So, it seems to me that a motivated worker could accomplish the scraping in one hard weekend's work.

No one said that the weekend also included other bottom prep or painting. However, for comparison, working essentially alone, I have several times prepped and painted the much larger bottom of our current 46 foot 44 foot LWL boat (two coats overall, three in high wear areas, Primocon where needed) in two long days. It takes me about two hours to roll on each coat of antifoul High cost of lay days in Oz drives even lazy buggers like me to superhuman (?) efforts!

But enough of talk about scraping, etc. IMO, considering the nature of the vessel, the stated usage and the experience level of the OP, waterblasting followed by antifouling would be my approach. Gilding that particular lily seems counter productive to the OP's desired outcome.

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