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Beneteau 361
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Discussion Starter · #1 ·
Bottom paint on the new to me Beneteau 361 is flaking in spots, probably because of too many layers, and I was wondering what should I do about it before the start of next season. The options are: do nothing, touch up or paint another layer. I know eventually I would have to remove the old paint and start from scratch, but I would rather not do it this year. The paint is Interlux Micron (ablative), and the boat is in fresh water.
 

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Look around Sailnet and you'll see that your problem isn't that bad at all.

I'd get a 6" random orbit sander from Home Depot and attach it to a shop Vac. Sand the entire bottom using 100 grit paper changing every 10 or 15 minutes (2 hrs), dust off, and then apply new paint. Even though I removed all the paint a few years ago, This is what I do each year using Petit Hydrocoat. The key to keeping it from flaking is sanding.

It's not that bad. In 4 or 5 hours you'll be sore but done.
 

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Beneteau 361
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Discussion Starter · #3 ·
You are right the old paint is still looking good...that and the fact that I hate sanding and dealing with dust are the reasons I am reluctant to do anything serious about it this year...

Are you suggesting sanding down to the barrier coat or just prepping the old surface and painting over? How toxic is the dust? What kind of protection would I need?
 

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I did my own work and therefore learned that the best way to have your boat's bottom done is with your pocketbook.

Of course the dust is toxic - the paint is specifically designed to kill things, isn't it?

If you would like to do it really right, have it blasted to the gelcoat, then apply a barrier coat, then the paint of your choice.
 

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Ablative paint such as Micron does this when too too many layers are built up and the earlier under-layers start to loose adhesion. The real solution is to only paint with ablative paint when you NEED to apply ablative paint. The best way to do this is to use a different color for the 'first coat' and only paint again when this 'indicator' coat is showing through.

Best /fastest way to get this off is to use a Fein tool (vibratory multi-tool) with a sharpened chisel blade attached and held at a very low angle. Remove only those sections that have poor adhesion and are easily removed, and wait (another year or two) for those that do not. Sand well, down into where the paint has been removed and fair the edges of where you stopped chiseling with 'thickened' new paint (mix of micro balloons + new paint) and a plastic TROWEL. Take pictures of those sections that need to be chiseled away so that you dont needlessly remove the paint later on when those sections not chiseled begin to lose their adhesion.
This will save time and money ... and shoulder 'bursitis'.

The SMOOTHER you apply Micron, etc. the longer it will last - think 'racing bottom' smooth. Suggest you apply Micron with a thin yellow WEST SYSTEM roller, then 'tip' your final coat with a polyethylene trowel ... but Im a 'fanatic' that likes my 'bottoms' to be smooth as a baby's ass.

Pic is 'after' chiseling with a Fein Tool. The layer that failed was the original 13 y/o indicator coat.


;-)
 

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Beneteau 361
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Discussion Starter · #6 ·
Thanks - this might be exactly what I am looking for if I decide to go that route. Wondering if all this scraping is safe for the original barrier coat?
 

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If you 'get down' to barrier coat, you'll need to 'roughen' it - 100 grit is the choice, just roughened to provide sufficient 'tooth' for the new paint, dont deeply 'sand' into the barrier - especially if you dont know the original lay-up thickness of the barrier.
If the OEM barrier is found to be 'rough' (very pimply) as when applied with a shaggy roller, then consider to 'fair' the surface with epoxy + micro-balloons, etc. before applying new paint.

If the boat was 'hot coated' - bottom paint applied over partly cured barrier - then Id suggest that you also scrub with HOT water to remove any 'amine blush' that formed during the 'curing' of the barrier. Since you dont know, Id suggest a HOT water scrub then 'roughen'.
Boats that are 'hot coated' are more prone to such 'flaking' of their ablative bottom paint later on - just my suspicion.
You dont want to do this job 'twice'; now and several years again in the immediate future.
;-)
 

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...Best /fastest way to get this off is to use a Fein tool (vibratory multi-tool) with a sharpened chisel blade attached and held at a very low angle. Remove only those sections that have poor adhesion and are easily removed, and wait (another year or two) for those that do not. Sand well, down into where the paint has been removed and fair the edges of where you stopped chiseling with 'thickened' new paint (mix of micro balloons + new paint) and a plastic TROWEL...
Would work, but you are just postponing the inevitable - because you have so many coats, you'll have to remove all the paint and do it again someday. Also, there are other brands of multitool for this job, Fein is the most expensive, and its hard to use because its corded.

Thanks - this might be exactly what I am looking for if I decide to go that route. Wondering if all this scraping is safe for the original barrier coat?
Are you sure you have a barrier coat or just the gelcoat? If it is just the gelcoat, I would just sand and paint over the patches, then later on when you are ready, have someone soda blast the paint off (PM me for recommendation - I am doing it on my boat this year) and you then apply the barrier coat and new bottom paint. This will be the ultimate protection.
 

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Would work, but you are just postponing the inevitable - because you have so many coats, you'll have to remove all the paint and do it again someday.
My preference is to only do this backbreaking job as necessary and as needed, removing only the paint that has failed adhesion.
Sure, eventually all will be removed but not as one whole single-step whopping job. With Micron CSC now approaching ~US$200/US gallon (Micron extra @ ~$240/gal) why would anyone prefer to remove such expensive paint especially if its still 'adhering' and still 'working'?
;-)
 

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Beneteau 361
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Discussion Starter · #10 ·
I am sure the boat has barrier coat since new. Soda blasting and starting over is another option I would like to explore, although it does seem wasteful considering the overall condition is not so bad.
 

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I intended to describe a quick sanding such that the existing paint is scuffed up. It's not necessary to go all the way down to gel / barrier coat if you're just over painting.

Using a shop vac hooked to the sander reduces dust tremendously. If you wear eye and ear protection, and a 3M dust mask and ball cap, you'll be adequately protected. I use the 3M commercial disposable masks that are thicker than the cheap paper masks.

Others are correct that ultimately, you'll want to go all the way to barrier coat which is of course a more involved project. But the method that I described is sufficient for an overcoat. Unfortunately, short of ignoring it or paying someone to do it for you, there is no escaping the grunt work. I hate bottom work too, but I hate paying people more. :)
 

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You got good advice here...

I'll add that I hand scraped the bottom of my trailerable, then sanded, and barrier coat, and it's a miserable job. It's extremely toxic, and just "vacuuming" it away isn't really enough, the stuff goes everywhere.

My $0.02 is if you are even slightly considering doing this WHOLE job, look into soda blasting. The painting isn't really hard, that includes the required replacement barrier coat after blasting. But removal is the big deal.

If you spot sand out the chipping places, you are nearly guaranteed to have more come end of next season. So it's a do it now, or do it later kind of thing.

This is what a bottom looks like that has been patched and patched over the years:


This is what it looks like to have ruined your back for life...


This is when things start to get better:


This is what it looks when you apply your brandy new barrier coat:


And this is what you get when you complete your bottom job and topsides in one winter (no I never want to do that again):
 

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And this is what you get when you complete your bottom job and topsides
Sweet job.

We did a similar job several years ago, removing the paint with wood chisels and carbide scraper followed by sanding with the 6" random orbit sander. Key was using 6" vs 5" because there is so much more surface area in the larger disk. Also key was using the ShopVac. Sucking off sanded paint keeps the disk clear and the job goes much faster. I also change pads frequently - every 10-15 minutes because the metal in the paint kills sanding pads. A link to the job follows.

Victoria Bottom Stripping & Fairing
 

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and thats a small boat!

yeah it sucks...if it where me a simple chisel scraper and touck up with a brush then roll over the touch up spots with a nice roller

however the inevitable is that what failing is not the top coat but the bottom adhesion so unless you want to do a complete job like the above boat you can do it every so often to your liking since the rest of the paint that is still stuck looks SPLENDID

that way you save a few $$$
 
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