# New bottom paint blues



## cptmclark (Jul 29, 2013)

I hope this hasn't been discussed recently here.
I just had my bottom painted on a Precision 23 that I use primarily for club racing. Old paint was a soft ablative and had to be blasted off, which is a sad tale in itself.

The sailboat shop convinced me that I don't want VC17 in our inland lake because I haul the boat out sometimes and also because we need a higher crud resistance. They recommended Sea Hawk Cucote. I now have a new Cucote bottom with Seahawk's extra anti slime additive.

The painter applied two coasts of "primer" paint and three coats of the Cucote. The paint job looks very nice but feels very rough. Very rough, like coarse sandpaper maybe. The idea he gave me earlier was that I'd want to burnish the paint, and there is enough on there to do that. I expected that to happen while it was lifted.

The issue is that to my surprise the painter refused to burnish the paint while the boat was hoisted. It's now on it's trailer, with the standing rigging up.

How do I burnish the paint? He suggested 320 sandpaper. I've tried that on the rudder and it did smooth it a bit. Some forum posters say to use a piece of carpet and just rub it.

Before I start, I would really appreciate any advice. My goal is to pick up maybe a tenth of a knot or more over what speed I had with the old soft ablative. After spending almost three grand I don't want to mess it up.

Thank you in advance,

Mike
Carmel, (landlocked) Indiana


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## Galo (Jun 8, 2015)

Mike:
The answer will depend on the condition/situation of the paint.

If the roughness is in the form of an 'orange peel' -observable irregularities in the paint that cause it to look like the skin of an orange, with observable 'bumps' and ridges- the only way to smooth it is sanding. U will remove some material, so....320 is good -and keep it wet. Use a flexible sanding block so that you sand off only the high spots in the paint. 

If the roughness is just 'grit' -meaning, it feels like sand got into the paint but you don't have that 'orange peeling'- I would also sand but with a finer sandpaper...600 or so. Keep it wet, use a block as u would for fixing the orange peeling. From your description, this last is what I think u have, so......I would try this on a small section of hull and see what happens....


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## cptmclark (Jul 29, 2013)

Thank you Galo,

Your second example is what I have, except there are roller marks and so forth as well, meaning it's not a smooth finish with some sand on it. Although it's an ablative paint it's a "hard ablative" meaning it won't come off on your hand without rubbing with water like the old chalky stuff would.

I sanded with 320 wet and a hard block, and with water of course it changes the color of the jet black paint to a brown color, more where the paper was the most wet, leaving a mottled look. Made me wonder if i could perhaps just "wash it smooth" with wet rags after getting the obvious ridges and high spots off.

The 1500 paper I followed with created more smoothness, and I'm not sure how much I should risk doing. When I use the word "smooth" I'm referring to before sanding, not the ideal. Someone mentioned brass wool saying it would just burning without removing any paint. I'm not sure that could be but eager to learn.

Anyway, thank you very much for the reply,


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## Stumble (Feb 2, 2012)

How crazy do you want to get? Burnishing is just sanding but typically with bronze (not steel) wool. The goal is to knock off the high points to reduce wetted surface and drag. A typical serious racer will wet sand to around 400 grit and call it a day. On the crazy end, the 70' race boat I worked for, was wet sanded to 1000, then used a polishing compound to make the bottom paint like glass.


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## cptmclark (Jul 29, 2013)

Stumble,

How crazy?" assumes some ability to guess how much work is needed to see some speed improvement. Comparing to the way it came from the paint shop, I know I've done some good (assuming that you really only need to do the front part and leading edges)

While I have it out is the time to do it, and if I could gain a tenth knot by more work, I'd do it. I don't really know how to measure smoothness without a microscope, except by feel. Each of the two go overs I've done made it smoother than the condition before. I thought of continuing to sand with the 1500, in once over sessions, until I couldn't feel any difference. I suppose I could leave a small area without further sanding so I could do a one-two check.

whadayathink?


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## Galo (Jun 8, 2015)

cptmclark said:


> Thank you Galo,
> 
> Your second example is what I have, except there are roller marks and so forth as well, meaning it's not a smooth finish with some sand on it. Although it's an ablative paint it's a "hard ablative" meaning it won't come off on your hand without rubbing with water like the old chalky stuff would.
> 
> I sanded with 320 wet and a hard block, and with water of course it changes the color of the jet black paint to a brown color, more where the paper was the most wet, leaving a mottled look. Made me wonder if i could perhaps just "wash it smooth" with wet rags after getting the obvious ridges and high spots off.


I second the post above....u can get as crazy (or anal -LOL!) as u want, but....I would do the 320 to remove ridges and roller marks and call it good. That will get you to the 90th percentile. The color will go back to black once the boat is in the water.

Once the boat has been in the water for a few weeks, if you snorkel, you can take 600 or 800 grit to it very lightly while the boat is in the water and that will take u to the 95th percentile...


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## cptmclark (Jul 29, 2013)

Thanks. I'm sold on stopping the work now. 

What do you think of the wisdom of front third only? I've been told that the rest is wasted work because the flow is turbulent there anyway. I'm lazy, but not so much that I wouldn't go farther for a good cause after coming this far. This is my first experience with the subject.

m


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## Stumble (Feb 2, 2012)

Nope, you need to do the entire hull. Leading edges are more important, but all of it matters. The entire hull needs to go down to 350-400 wet sanded, after that you get progressively less speed increase for a lot more work. You might want to consider doing just the leading edges to 700-800 however.


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## cptmclark (Jul 29, 2013)

Drat. I truly liked the first third only opinion better.

Very hard to do sitting on a trailer with the 18 inch high eight foot long keel in a track. Centerboard is impossible.

Back third is not so bad but the middle requires a young and limber body.


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## Stumble (Feb 2, 2012)

I feel your pain. I wound up taking my J-22 on a trailer all the way to polishing compound on the trailer. Took me more than a month in total.


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