Cleaning bottom paint scum

J

Jazzmanic

New member
As you may recall, we got C-Dancer bottom-painted by the factory almost exactly a year ago in anticipation of mooring the boat in salt water last summer. In hindsight, I realize it was the right thing to do but we got so used to looking at our clean, smooth, beautiful C-Dory green gelcoat on the bottom of the hull when it was dry-stored for so many years. Now, after a season in the water, the bottom looks pretty ugly with lots of dried green and white scum. I'm 95% sure we'll probably go back to dry storage this season and can't stand looking at that ugly bottom, especially when it's on a trailer for everyone to see. I wouldn't mind a clean, black bottom but the way it looks now is unacceptable.

So I have some questions: What is the easiest way to clean off all that ugly green scum? Should I pressure wash or would that take a lot of the bottom paint off as well? Since it's on a trailer, should I have a professional haul it off the trailer, put it on stands and pressure wash? Will it come off with heavy scrubbing with a brush?

What do you do?
 
Is the boat out of the water now? Some bottom paints require periodic wipe downs when they are in the water, even with bottom paint--what bottom paint was used?

When you first haul the boat out of the water, at the end of a season, the pressure washer, or even a green scotch pad will take the slime off easily. Now that it has dried--is an entirely different story--and may be hard to get off.

I happen to like Vivid bottom paint--and have used it for 3 years now on the Caracal--2 years were in the water full time--and I pressure washed it one time. It has been in and out a bit during the last 6 months--and just in for 3 weeks. At the end of the 3 weeks, there was a little slime and growth right at the water line. That came off with a wash cloth. The paint still looks great, with bright colors--although I will put another coat of paint on if I leave it in the water more than a month at a time.

You are pretty much stuck with some bottom paint now--It will be difficult to get all of the paint off, and back to the "clean" gel coat.
 
The boat is on a trailer right now and has been since November. So it sounds like the time to get the greenish slime off would have been when it came out of the saltwater. Would pressure washing get it off or would it wash off the bottom paint too? We had Micron Extra put on, two coats. It seems to be holding up well after only 6 months in the salt.

I'm not planning on taking the bottom paint off and repainting it with topcoat, I just want the black bottom paint to look black again without having to add another coat of paint.

Peter
 
I would start with a power wash and see how you make out. As others have said, the ideal time is to power wash as soon as it comes out of the water.

Good luck with the effort.
 
matt_unique":1jbw4q71 said:
I would start with a power wash and see how you make out. As others have said, the ideal time is to power wash as soon as it comes out of the water.

Good luck with the effort.
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Now you tell me.... :roll: :wink

Peter (lol)
 
Peter,

I have a similar problem every year. Even though I do a power wash on haul-out it generally looks pretty cruddy by the time we put back in.
So I do another wash just before lauching. This also exposes a "new" surface of paint to the "beasties" and re-activates it.

A good pressure washer is quite capable of removing all of your bottom paint and probably the gelcoat too so it needs a gentle touch and you need to let it dry out to see the spots you have missed :-)

You can also wipe gently with one of those 3M dishwasher pads but be aware that you are dealing with a toxic substance. My marina does not allow any bottom washing (Boat bottoms that is) :monty so I am occasionally forced to go very fast for a few miles. Believe it or not it does work. I can measure the difference after about 30 minutes.

Merv
 
Remember, it doesn't need a great big power wash. A good washer is this from Harbour Freight:Electric Power Washer.

It has several advantages: Cheap and electric, so you don't have another gas engine to maintain. It'll do the job whenever you've pulled the boat, but you do have to pull the boat.

Boris
 
Grumpy":349yqqvs said:
Peter,


A good pressure washer is quite capable of removing all of your bottom paint and probably the gelcoat too so it needs a gentle touch and you need to let it dry out to see the spots you have missed :-)

:monty so I am occasionally forced to go very fast for a few miles. Believe it or not it does work. I can measure the difference after about 30 minutes.

Merv
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The soft ablative paints will be removed by a pressure washer, but hard paints will not be completely removed. Even a 4000 PSI, 4 gal per min commercial (13 hp gas engine) will not remove gel coat--you need soda blasting. However, you can damage gel coat by pressure washing it with high pressure.

As for running the boat at speed and removing any slime or growth on the bottom--I am very pessimistic. For example, I had some "whiskers" on my lower unit, where the skeg was in the water for 3 weeks--and I had not refreshed the TBO bottom paint. Running the boat for 30 minutes at 30 knots made no difference in the amount of "whiskers"--or growth on the lower unit.

When we raced sailboats, we either wiped the bottom down with coarse rags or 600 to 1000 sandpaper each week (depending if there was any visible "slime" to be sure we had an absolutely clean bottom.
 
Peter,

I hope you did not understand my post as suggesting that you should try to remove your bottom paint with a pressure washer. It was just warning that you can easily remove more than you intended depending on the paint. I can drill holes with my washer !!

Bob, I agree that speed seems to do nothing for the whiskers on my lower units or my trim tabs but I have on numerous occasions noted that a burst of speed for 30 minutes or so changes my cruise speed by a knot or so for identical rpm afterwards. I did not notice this in my last marina which was a covered slip but I am now in an open slip and have much more soft growth even on the tabs which I have had to paint. Must be the excessive sunlight we get up here :-)

M
 
Our bottom paint discolors (goes from black to a grayish/green) at the waterline after a couple months in the water. No amount of scrubbing takes away the discoloration without removing a bunch of the ablative paint. If it really bothers you, touch up the area along the waterline. I did that after a couple seasons with our first bottom paint go-round, and got another year out of it.

I have had to endure the agony of sneers and stares when folks look at the boat with wearing bottom paint. :wink: Price out a gallon of bottom paint - it will help you get over the shame.

Best wishes,
Jim
 
The vest solution is to put the boat in the water so you can't see the bottom paint. Other than that (as Jim points out) you're pretty much stuck with it unless you want to repaint with bottom paint. For what it's worth, I still like you regardless of what your bottom looks like. :wink:
 
ROFLOL!!! :lol:

Ok, ok, I know I need to get over it. I'll scrub the best I can without pressure washing (although that was a nice pressure washer at Harbor Freight, Boris), and then just live with how it looks until we repaint in 2 or so years. I guess the good thing is that we won't be trailering that much so I guess I can deal with the snickers Jim. :oops:

And Roger, lookey but no touchie!

All the rest, thanks for your contributions. At the very least, it will give me an excuse to open it a WOT and see how much green falls away.

Peter
 
Peter,

Whichever way you do it the green that falls away will be US $ :-) unless you are North of that dotted line on the water.

Why the heck are you worried about how your lower 48 looks on the trailer.
As Jim says. put your butt in the water and ignore them all.

You can tell it's that time of year again and that's even without FDD's in the equation :-))


M
 
Grumpy":300rhc1x said:
Peter,

Whichever way you do it the green that falls away will be US $ :-) unless you are North of that dotted line on the water.

Why the heck are you worried about how your lower 48 looks on the trailer.
As Jim says. put your butt in the water and ignore them all.

You can tell it's that time of year again and that's even without FDD's in the equation :-))


M
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You're so right Merv. I'm ready for boating season to start!

Peter
 
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