Bottom Paint Question

[The Hedgehog]

I have a friend that is going to bottom paint a 16' dink. How much paint and primer is needed for such a job.

[silverghost]

I would say less than 1/2 quart of primer and 1/2 quart of bottom paint !

[Buddyc]

Silverghost is right. a quart of each is all you need.I dont think you can buy any less than a quart? seal it tight and you can use it again

[The Hedgehog]

Thanks guys.

[Conquistador_del_mar]

I have a friend that is going to bottom paint a 16' dink. How much paint and primer is needed for such a job.

Bill,
Are you talking antifoul paint or something else? Another Bill

[The Hedgehog]

Bill,
Are you talking antifoul paint or something else? Another Bill

Antifoul . Freshwater

[Conquistador_del_mar]

Antifoul . Freshwater

In that case, he really should roll on two coats. As you know, it is a self sacrificing paint that sloughs off over time. One coat will not last very long at all. A roller will absorb quite a bit, but if he wraps it in plastic then he can roll on a second coat using the same roller. I think he will need two quarts to do the job right. Just my thoughts. Bill

[The Hedgehog]

In that case, he really should roll on two coats. As you know, it is a self sacrificing paint that sloughs off over time. One coat will not last very long at all. A roller will absorb quite a bit, but if he wraps it in plastic then he can roll on a second coat using the same roller. I think he will need two quarts to do the job right. Just my thoughts. Bill

Yes, for the price point difference, the next step up is a gallon. He will probably do that and do several coats of the antifoul

[CHACHI]

Bill, paint the last coat a different color than the first coat.

Being an ablative paint, when the second color (first coat) starts to show, it is time for another coat.

If both coats are the same color you won't see a difference until the paint is all gone and you are down to the gel.

Ken

[The Hedgehog]

Bill, paint the last coat a different color than the first coat.

Being an ablative paint, when the second color (first coat) starts to show, it is time for another coat.

If both coats are the same color you won't see a difference until the paint is all gone and you are down to the gel.

Ken

I would do that. This guy is doing it on a budget and does not want to buy anymore than he needs to use.

[MOP]

If it is a new boat first time prep is of extreme importance, gel loves to shed bottom paint. First time around it should be lightly sanded and solvent washed to get rid of the mold release wax, then a light but even coat of primer and paint of choice. Doing right from the get go will save a lot of grief down the road.

Phil

[glashole]

use the proper primer

[silverghost]

I have always had good luck with a good liquid floor de-waxer & a scotchbrite to get rid of the mold release wax agent~~~~~~~

Followed up by Interlux AL-200 Primer !

[fysis]

Just read the thread here about antifoulpaint. Just curious if anyone have measured/noticed any topspeed difference beetween a "clean hull" and an antifoul painted. Heard the fastest hull should bee 400 grit finish then you have water to water contact which should bee the least restrictive way for the hull through the water?

[Walt. H.]

[ QUOTE=$originalposter]fysis

Antifoulpaint vs speed.
Just read the thread here about antifoulpaint. Just curious if anyone have measured/noticed any topspeed difference beetween a "clean hull" and an antifoul painted. Heard the fastest hull should bee 400 grit finish then you have water to water contact which should bee the least restrictive way for the hull through the water?

{$pagetext}[/QUOTE]

Yes regarding the 400 grit sanding, it breaks the surface tension also known as stiction especially with shiny waxed bottoms.

Regarding bottom paint vs not painted: yes paint will cost you mph but crusted hanging marine growth will cost you more.

[silverghost]

I boat 95% of the time in Ocean City NJ in saltwater.
All my boats sit in the boatslip with direct saltwater contact all summer season long for six months.

The very last new boat I bought lost approx 12% in top speed with Micron CSC extra antifouling ablative bottom paint.

I first de-waxed this hull bottem, then lightly sanded followed by Interlux AL 200 primer followed by several coats of Interlux Interprotect osmotic blister barrier coat followed up by the blue Micron CSC extra antifouling paint.
If I had not used this paint system I would have picked up all sort of marine growth & possibly gellcoat blisters..
The extra Interprotect layer was applied as insurance to prevent any possible gellcoat blisters from forming.

The 12% speed loss wit a painted bottom is my cost of letting my boats sit season long in saltwater.

[Ghost]

There's an interesting article in Power & Motoryacht right now about a new bottom paint that works by being nonstick. Such that if you leave your boat in the water, but take it out (13 MPH or more they say) at least once every two weeks, anything that does get on it will just slide right off. (I presume the transom would need a quick brushing.)

Claimed to improve speed both by keeping the bottom clean AND by being a better running surface than other paints.

Supposed to last 5 years.

$800/gallon, however. Probably because they sell a lot to the military.

[biggiefl]

I have owned MANY boats with bottom paint, especially when I lived in NJ. I never noticed much of a loss, 12% seems way extreme as my 21 Scarab was painted and did 60+. 12% loss would have made it a 68mph boat clean...not gonna happen. If the job is good it should not rob more than 1-2mph max...if any.

[MOP]

I have posted on this a few times, as some know I was an avid sail boat racer. For many years I spent hours sanding then we sanding bottom paint to make is as smooth as possible. Those of you that follow the Americas Cup may remember that Dennis Conner applied Boeing Rivulets to USA when he raced in Australia. It got me thinking and looking into "The Stiction Layer" after much poking and reading the next spring I rolled my bottom paint on with a very short nap roller. The result was better speed across the board, I had already done well locally and decided to give the Block Island race a try. I did way better than expected ended up winning my division plus boat overall, got a nice write up in Soundings. I proved to quite a few that light stipple is faster than smooth! Does the stipple carry into higher speeds? Someone who stays in the water needs to try it on their Donzi, for now my bottom is sanded with #220.

[biggiefl]

Maybe but I doubt it at higher speeds. Sombody has tried it though and a quick google search should find it.

There was a company(1960's?) that thought since dimples on a golf ball make it go farther it would make a boat go faster. What it actually did was cause suction and the boat would literally stick to the water. Many differences between aero and hydro dynamics.

[Greg Guimond]

Dragging this one back TTT. I have never used bottom paint and have a question. If your goal is to be able to easily remove bottom paint so that a next owner can go back to the unpainted bottom, can you just roll on two coats of bottom paint, with no primer? Will this let the anti-fouling just wear off more quickly or will it cause bottom problems?

[silverghost]

Greg~~~
Because I have a boat that sits in saltwater all season long for six+ months I have used Interlux interprotect to prevent underwater osmotic blistering, and then I applied their aluminum AL 200 primer~~~after de-waxing & sanding the bottom.
Finally I top-coated with Micron CSC Extra ablative(shedding) bottom paint.
It would be very tough to ever get my bottom paint , primer, and blister coat off & free to the bare fiberglass ever again.

My neighbor however did Not use the interprotect blister coat and then not the aluminum AL 200 primer.
He put the Micron CSC Extra ablative bottom paint directly on his bare un-sanded hull bottom after de-waxing.

In the fall he uses a high-pressure washer and gets a flood of shedding bottom paint color in the street.
His bottom paint seems to shed far more easily than mine does~~~~We both use the very same Micron bottom paint.
Still that un-sanded & un-primed bottom with Micron ablative style bottom paint still hangs on fairly tightly to his un-primed & unsanded slick bottom.

I would hate to have to ever try to remove it completely to the bare fiberglass with Interlux stripper !
Soda Blasting the bottom would be the only real option to easily remove that bottom paint it in my opinion.

If you use standard non-ablative, or Vinyl, bottom paint without primer it might be far harder to remove later that the more expensive ablative shedding style such as Micron CSC Extra .

Just my thouhts~~~
I suspect few on this forum use any bottom paint on their Donzi speedboats ?

[Greg Guimond]

What is I did not de-wax and sand the bottom? Just roll on two coats and done?

[silverghost]

What is I did not de-wax and sand the bottom? Just roll on two coats and done?


Greg~~
If you do not de-wax , or sand, or prime, the bottom hull first I think it would be far easier to remove the bottom paint with a very strong pressure washer, or by wet sanding , scotchbrite, etc later if ever needed.

Be sure to use soft Ablative (shedding style) bottom paint as this type of bottom paint is FAR easier to totally remove if necessary, & ever desired, later .

Why not try to roll-on ONE coat with a low nap roller so less total paint thickness is on the hull ?

I get two complete, six month+, summer saltwater seasons out of two coats of Micron on my skiboat.

[Greg Guimond]

That sounds interesting and what I was hoping to hear. I'm thinking you could go back to a glass bottom with not a lot of effort for a next buyer. I've never used bottom paint so have to think it through.

[Morgan's Cloud]

If you put bottom paint on a bare/unsanded/unprimed gelcoat bottom it will indeed come off easily. Too easily . It will all come off while the boat is in the water.

If you sand/rough up the bottom without any primer/barrier coat and apply anti fouling , the scratches will absorb and hold the colour pigmentation , thus later when the paint is removed , there will be a nasty blush on the bottom that wont come out.
This is also what a lot of people out here used to do in the early 60's and onwards for a long while when fiberglass boats were getting established. I've since seen many if those boats out of the water and they're an osmotic blister fest.

If you really do need to put paint on the bottom of a boat don't worry about the guy after you. You're doing it for yourself so do it right. No shortcuts and it will pay off in the long run.
A good epoxy barrier coat is essential and when done right later on down the road a guy who knows his stuff with blasting can remove the anti fouling all the way down to the barrier coat without harming it and you can start fresh again without re-barrier coating.

[Greg Guimond]

Good feedback all around. Thanks guys. It sounds like you either do it complete for the long haul, or leave it bare fiberglass and crane it out on occasion to power wash and elbow grease the bottom clean which is a total PITA. Maybe a compromise is to do a "bikini" anti-fouling application. Just half the actual bottom so that at cruise speed you would not even see the bottom paint. Keep it under the side chines so no water line and no transom. Maybe this would cut the work effort on the rest of the bottom down substantially and still be a proper application for the area that was treated.