Thinning West CPP bottom paint.

[wdonovan]

My boat had epoxy Barrier coat done by previous owner. The coat of bottom paint over it looks very thin and I think that was his intentional plan. I like that approach because I would prefer just as much of this highly ablative paint as is needed to get through a season. That way I don’t wind up with a buildup that Hass to be removed after a few years. I sell toms River in Barnegat Bay New Jersey and the barnacle problem is nearly nonexistent here. I can count the number on the hall with one hand and probably have just two dozen between the Keelen Rutter . Does anyone thin this paint? If so how much?

 

[dlochner]

I would only thin the pain according to the manufacturer's recommendation.

Use a short nap roller to get a thin coat, sometimes called a mohair roller.

https://www.lowes.com/pd/Purdy-White-Dove-2-Pack-6-5-in-x-1-4-in-Mini-Woven-Synthetic-Blend-Paint-Roller-Cover/1002554986

 

[Davidasailor26]

+1 for the short nap roller. I use 3/16” (shorter than you can get at most big box stores) and it puts on a pretty thin layer.

 

[Ralph Johnstone]

Can't see why you'd want to thin out the paint when the manufacturer recommends two coats - unthinned. I switched from Micron CSC to WM CPP ten years ago and it's the best thing I ever did with bottom paint. In 2012, applied two coats of CPP and didn't need to re-coat until 2019. Seven years and no show through of the bottom coat. And that's with good mileage every year.

I gauge the need for new paint by the first black coat, subsequent coats are blue. Keep going until the black shows through and you avoid excessive thickness. Maybe you've experienced thick coats falling off which makes one hell of a surface. Avoid by always allowing a full day for the bottom paint to dry out from the water after being hauled. I may have excessive thickness in place but they're all so smooth you can't detect them.

 

[Joe]

Ablative paint, by its very nature, doesn't really "build up" It is designed to slowly erode as the boat moves through the water. If you're using a hard shell, modified epoxy type paint, then yes, it can build up over time, because it works by slowly emitting its anti fouling properties rather than sloughing off microscope layers. Boats that are not kept in the water year round normally use the ablative type paint because it's not affected by sun, air and weather the way the hard shell paints are.
What is my point? You should be able to simply apply a few new coats of paint each year, right over what's left of last year's covering. Don't try to get too smart when it comes to expensive marine paint. Read the manufacturer's directions and follow them... especially temperatures at application.

 

[RoyS]

Use a chemical resistant foam roller for an adequate and thin coat. Been using foam rollers for over thirty years. Generally I only do a full recoat about every four years with just hand spot touch ups with a brush between. I never sand. One gallon of bottom paint will cover my 33' with a foam roller. I use Petit Hydrocoat. No build up with this system.

 

[Art12050]

+1 for the use of a foam roller. Very smooth, easy to use and applies a nice even coat with the right mil thickness. Mixing is always a hassle as after sitting for months it gets pretty well separate. If you’re on good terms with a local paint or hardware store they’ll usually shake it up for you. Otherwise you can dump it into a 2 gallon plastic pail and give it a good stir.
I’ve been using Blue Water Paint Copper Pro SCX for a number of years but they’ve stopped production because some of the additives have been ban. I’ll probably go with Petit Odyssey or Hydrocoat.
Our mooring is located at the Sound End of Plum Island Sound in Ipswich Ma. There’s a huge estuary above us that drains and fills with the tide so there’s water constantly moving over our hull except for a few hours at slack water. Even a multi-season ablative get worn down in one season.

 

[wdonovan]

Thanks for all that guys. My plan to thin was because my last boat (also my first) had probably 1/8" paint and steps where the loose paint had been scraped off. I never want to get to that so I thought by thinning I could get through a season and each year, replace what it had lost. I will take heed and refrain from thinning.

 

[Crazy Dave Condon]

As a dealer I always painted a third time at the water line and down for a foot as that is where the paint takes a beating.