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Old 01-03-2016, 13:44   #1
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Inaccessible Bottom Parts

My 2013 Beneteau Oceanis 48, is on the hard for it’s second bottom job. The first time out, I let the yard do its thing without much supervision or input. This time, interesting questions are surfacing to which neither I nor the yard personnel seem to know the answers.

The elliptical shape of the saildrive shaft drops through a round hole in the hull of the boat. The resulting void is covered by a two part panel that is flush with the bottom of the hull.

There is an approximately 1/2" gap between the panels and the saildrive shaft. I am guessing that the space between these panels and the place where the drive passes through the structural part of the hull is about six inches.

Whatever the precise measurements, there is a void above the bottom of the hull and below the top of the saildrive housing assembly where several gallons of water are free to slosh to and fro.

It seems like it would be a fairly major undertaking to remove those panels to gain access to the top of the saildrive housing assembly for debris removal, cleaning and painting. On the one hand, doing this as a part of a normal bottom job seems excessive. On the other hand, totally ignoring that whole part of the sail-drive seems sloppy.

What is the normal and recommended procedure for dealing with this hidden part of the saildrive housing?

I have a similar issue with the bow thruster. While none of that surface area is hidden, a lot of it is poorly accessible—if not for painting then at least for sanding. Like the saildrive fairing, there is a separate piece that runs the full width of the bow thruster cylinder’s underside. It looks like it was put there to provide access to this area but, perhaps it was put there just to make installation easier. Would it be a major undertaking to remove and replace?

How should I be thinking about removing the old paint from this part of the hull? How to paint it afresh? It looks like the paint was just slopped on with a brush last time. Sooner or later the old paint is going to have to be removed.

Suggestions anyone?
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Old 01-03-2016, 14:17   #2
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Re: Inaccessible Bottom Parts

Does it make any harm if there's grows a few barnacles or algae? If not why to bother. Thou if your boat were steel it certainly would. One STA vessel allmost sinked due bottom work allways done in the same yard. They supported the vessel at the same spot every time which were eventually rusting throw and had a major leak in the Caribean.
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Old 01-03-2016, 15:21   #3
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Re: Inaccessible Bottom Parts

Well, I guess growth won't cause drag in those areas. Just feels wrong to be growing barnacles anywhere on a three year old yacht. I also worry about corrosion on the invisible portion of the saildrive leg.
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Old 01-03-2016, 15:34   #4
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Re: Inaccessible Bottom Parts

Where is the cooling water intake on the sail drive in relation to this non-accessible part of it. That needs to be clean and free from barnacles etc.
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Old 01-03-2016, 17:47   #5
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Re: Inaccessible Bottom Parts

That is well below the insert. No problem there.
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Old 01-03-2016, 20:17   #6
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Re: Inaccessible Bottom Parts

I was going to say, "Be nicer to your lady", but I guess the thread is about something else...
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Old 09-03-2016, 12:40   #7
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Re: Inaccessible Bottom Parts

Well this little project has gotten more interesting. I contracted for the bottom job through the yard specifying that both coats of existing anti-fouling be removed and two full coats of red Trinidad SR be applied followed by a third coat at the waterline and on the leading edges of the keel and rudder.

Initially, the yard roughed up the outer coat of anti-fouling a bit and declared themselves ready to paint. When I insisted that they get all of the second coat (red) and most of the first coat (blue) off, they grumbled about the extraordinary nature of my demand and went back to work. This time they also went all of the way through the barrier coat (grey) to expose the gelcoat on about 50% of her bottom. Then they doubled the original estimate for the job to account for the "extra" sanding + the labor to put on a new barrier coat. I stopped all work and plan to finish it myself. Which brings up a whole bunch of questions . . .

1. Should I have expected them to go through so much of the barrier coat?

2. Given that I intend to use Trinadad SR again, does it matter what paint I use for the barrier coat?

3. How many coats of barrier coat should I plan to put on?

4. Given the experience I just had, I am thinking about starting with a layer of black Trinidad and covering that with a coat and a half of red. Next time, I'll just have them take all of the red off. Good plan?
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Old 09-03-2016, 13:58   #8
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Re: Inaccessible Bottom Parts

1. Should I have expected them to go through so much of the barrier coat? I would say you should have expected them to do it, but it's a pretty common issue. You are talking about a barrier coat of about 5 mills and a very hard bottom paint that takes an aggressive sand paper to remove. Scoring into the barrier coat or gel coat would be a predictable issue.

2. Given that I intend to use Trinadad SR again, does it matter what paint I use for the barrier coat? paint isn't a barrier coat, use an epoxy Barrier Coat and put it down first, then you paint. The new barrier coat needs to be compatable with the old barrier coat, or you also have to remove all the old barrier coat. Since you are staying with the same paint, just reuse whatever barrier coat you used the first time.

3. How many coats of barrier coat should I plan to put on? i would suggest reading the instructions on the can. The number of layers depends on the application method. The thickness required depends on the specific product used. All of this is easily available from the manufacturer.

4. Given the experience I just had, I am thinking about starting with a layer of black Trinidad and covering that with a coat and a half of red. Next time, I'll just have them take all of the red off. Good plan?[/QUOTE] Nope this sounds like another disaster in the making. Again if your refer to the paint label it requires two coats to be applied after the barrier coat is on. So put two full coats on. It is a good idea to use contrasting colors so that when you burnish it you know when to stop.


Frankly this sounds like you caused a massive mess. A good barrier coat job is typically something you do once in a boats lifetime, racers may need to do it more often, when the film thickness of the hard paint gets too thick and has to be removed, but this certainly isn't a every year thing.

The proper way to handle Trinidad SR is first a good barrier coat to the manufacturers specs, two coats in contrasting colors initially, then once a year (typically just before the spring) a light sanding with 80 grit to provide some tooth for the next coat, and then a single coat of new SR applied over the top. Basically what the yard tried to do and you told them not to.
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Old 09-03-2016, 15:55   #9
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Re: Inaccessible Bottom Parts

Thanks for the detailed reply. A few clarifications/new questions in blue.

2. Given that I intend to use Trinadad SR again, does it matter what paint I use for the barrier coat? paint isn't a barrier coat, use an epoxy Barrier Coat and put it down first, then you paint. The new barrier coat needs to be compatable with the old barrier coat, or you also have to remove all the old barrier coat. Since you are staying with the same paint, just reuse whatever barrier coat you used the first time.
What's left of what is on there now is whatever Benneteau put on, probably in France, less than three years ago. I will try to find out. Seems like though—unlike anti-fouling paint—epoxy based barrier coats should all be more or less compatible. I was wondering if a Pettit product like Pettit Protect would be a better choice than something from a different manufacturer relative to it's compatibility with the Trinadad.

4. Given the experience I just had, I am thinking about starting with a layer of black Trinidad and covering that with a coat and a half of red. Next time, I'll just have them take all of the red off. Good plan?[/QUOTE] Nope this sounds like another disaster in the making. Again if your refer to the paint label it requires two coats to be applied after the barrier coat is on. So put two full coats on. It is a good idea to use contrasting colors so that when you burnish it you know when to stop. Hmmm. Looks like what you are calling a "disaster in the making" is the same thing you are also advising the only difference being my extra bit of red at the waterline and on the leading edges. Perhaps you thought I was considering skipping the barrier coat step.


Frankly this sounds like you caused a massive mess. A good barrier coat job is typically something you do once in a boats lifetime, racers may need to do it more often, when the film thickness of the hard paint gets too thick and has to be removed, but this certainly isn't a every year thing. I did come at this from a lifetime of racing which may have created my problem. For my last ride (Evelyn 32) we hauled her annually and took all of the anti-fouling off ourselves (two coats of ablative paint in contrasting colors) without material disruption of the barrier coat and put two, new contrasting colors of ablative back on.

The proper way to handle Trinidad SR is first a good barrier coat to the manufacturers specs, two coats in contrasting colors initially, then once a year (typically just before the spring) a light sanding with 80 grit to provide some tooth for the next coat, and then a single coat of new SR applied over the top. Basically what the yard tried to do and you told them not to.
The first coat of anti-fouling paint (blue) was very well done. In retrospect, I should have left that one mostly intact. The second coat (red) was much less well done and was flaking off in chunks especially near the waterline. That crap absolutely had to go. All of it.

Live and learn. Thanks again for your input. I think if I had been in your yard, my education would have been less expensive.
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