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Scrub the bottom-paint or leave it be ?

Dec 1, 2020
92
CAL 27 Illahee / Brownsville WA
We had our new-to-us sailboat painted with Micron CSC on Dec 2nd 2020.

1616348024348.png


It's been sitting in the slip for nearly 4 months now and there is a blackish "scum" on the blue paint now. In May the boat will move to the mooring behind the house for regular sailing.

Is simple sailing enough to get this black slim growth to sluff off or should we hire someone to dive and scrub the bottom before sailing starts? If cleaning is generally considered a worthwhile activity, do most hire someone or use a DIY pvc type scrubbing pad setup that I have seen from time to time?

All thoughts appreciated.
 

Tom J

.
Sep 30, 2008
1,998
Catalina 310 Quincy, MA
A lot depends on the type of sailing you will do. For racing, you want the bottom to be spotless. For recreational sailing or cruising, not to worry, especially if the scum is mostly at the waterline. If you see a heavy green growth or barnacles, then that needs to be dealt with.
In my area, I like to scrub the waterline with a stiff brush every time I go for a swim, and then occasionally dive with a snorkel and deal with barnacles or heavy growth. I suspect the water in your area is too cold for that, so an occasional cleaning from a professional diver might be in order, unless you do your own diving with a wet suit.
 
Dec 25, 2000
5,048
Hunter Passage 42 Shelter Bay, WA
Hi Rick, do you know whether the bottom paint is ablative or hard paint? If ablative, no scrubbing as the green stuff should wash off under sail. Scrubbing destroys the ablative properties. Hard paint okay to scrub.
 
Dec 1, 2020
92
CAL 27 Illahee / Brownsville WA
Hi Rick, do you know whether the bottom paint is ablative or hard paint? If ablative, no scrubbing as the green stuff should wash off under sail. Scrubbing destroys the ablative properties. Hard paint okay to scrub.
I'm 99% sure Micron CSC is ablative.
 
Oct 22, 2014
16,103
CAL 35 Cruiser moored EVERETT WA
Rick. Couple of directions used. If you get your boat out on the water and your able to push it at hull speed frequently the paint should do it’s job and the scum/slime and bottom growth will slough off as intended. Note this takes a bit of time and speed through the water. Going out and floating at a couple knots with the tide is not enough for the water to scrub the hull “clean”.

Since I choose to change my zincs regularly, and I do now have the gear to do it in our chilled waters, I have a diver do the deed. While there he gives the hull a light scrub with a scotch bright pad on the bad spots or knocks off any growth that might be starting. Your frequency will vary. I find the marina mates have me checking and changing the zinc about every 6 months to be sure I keep the shaft and prop safe. The zincs are not completely gone but they will not go a full year with raising my concern. It is a preventative schedule.
 
Jan 4, 2006
3,905
Hunter 310 West Vancouver, B.C.
Have the bottom power washed at you marina every year when you half haul for inspection and zinc replacement. Worth about $100.00 C last year.
 
Oct 22, 2014
16,103
CAL 35 Cruiser moored EVERETT WA
Man if you open the border I’m bringing my boat up to haul, spay the bottom and inspection. It’s more than $350 USD to haul to change zincs and have the boat washed in Port of Everett.

Besides it would be fun to help the support the Canadian economy with some pub and good beer time.
 

dLj

.
Mar 23, 2017
1,829
Belliure 41 Now on the Chesapeake
Rick. Couple of directions used. If you get your boat out on the water and your able to push it at hull speed frequently the paint should do it’s job and the scum/slime and bottom growth will slough off as intended. Note this takes a bit of time and speed through the water. Going out and floating at a couple knots with the tide is not enough for the water to scrub the hull “clean”.

Since I choose to change my zincs regularly, and I do now have the gear to do it in our chilled waters, I have a diver do the deed. While there he gives the hull a light scrub with a scotch bright pad on the bad spots or knocks off any growth that might be starting. Your frequency will vary. I find the marina mates have me checking and changing the zinc about every 6 months to be sure I keep the shaft and prop safe. The zincs are not completely gone but they will not go a full year with raising my concern. It is a preventative schedule.
John, seems too frequent to me. Have you thought to double up your zinc's? I was always taught zinc's should really last a full year or you are under zinced... So to speak

dj
 
Feb 14, 2014
5,708
Hunter 430 Waveland, MS
John, seems too frequent to me. Have you thought to double up your zinc's?
John, @jssailem has a AgCl reference probe to check his Zinc's and look for stray DC Currents.
Peace of Mind and saves $$ to know how his boat is protected too.
Jim...
 

dLj

.
Mar 23, 2017
1,829
Belliure 41 Now on the Chesapeake
John, @jssailem has a AgCl reference probe to check his Zinc's and look for stray DC Currents.
Peace of Mind and saves $$ to know how his boat is protected too.
Jim...
@JamesG161 and @jssailem Nice to be able to measure, but it is generally considered that your zinc's should last at least 1 to 2 years, not every 6 months. If desired, the zinc's can be increased in size and location if longer than that is desired.

If John has to change out his zinc's every 6 months, he's under zinced.

dj

p.s. reference being used for above is "The Corrosion of Metals in the Marine Environment" by Fink and Boyd, page 78.
 
Dec 25, 2000
5,048
Hunter Passage 42 Shelter Bay, WA
I have our diver place two heavy zincs on the prop shaft; good for year. Due soon. Been doing this ever since owning the boat in 2002. Prop and all the bright work below the waterline remain as new.
 
Jan 4, 2006
3,905
Hunter 310 West Vancouver, B.C.
Man if you open the border I’m bringing my boat up to haul, spay the bottom and inspection.
OMG o_O ..................... sorry if I made you spill your afternoon coffee but that $100 dollars was in addition to the half haul out charge. If you want to scrub-a-dub-dub by yourself in the water, you can save the $100.00.

1616369648562.png


So all in for a half haul and pressure wash is ($274 + $100) = $374 for me.
For you ($308 + $133) = $441

C'mon, American exchange and a few other bonuses thrown in, how can you go wrong ? I'll even meet up with you and from there we can go to Snug Cove on Bowen Island and really get hammered without anyone knowing who we are. Everyone over there knows @Meriachee from previous incidents so he can't come along.
 
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dLj

.
Mar 23, 2017
1,829
Belliure 41 Now on the Chesapeake
Well errr uhhhh NO.
Lot of variables on Zinc consumption.
Jim...
All variables are known, or can be known. Correct zinc sizing and placement should give 1 to 2 years of service - I cited a known external reference document for that statement - what reference are you using for your answer? Just curious.

dj
 

Tom J

.
Sep 30, 2008
1,998
Catalina 310 Quincy, MA
Well errr uhhhh NO.
Lot of variables on Zinc consumption.
Jim...
:plus:Experience shows that no two seasons on the water are alike. I might anchor in a new area for a couple of weeks. I might get a new neighbor at the dock. I generally put a new zinc on at the beginning of the season, and check it periodically. I can change the zinc in the water fairly easily if needed.
 
Oct 24, 2010
2,399
Hunter 30 Everett, WA
Here in Puget Sound it's illegal to scrub ablative copper based paint while in the water. And the fine is significant.

Ken
 

dLj

.
Mar 23, 2017
1,829
Belliure 41 Now on the Chesapeake
Ah that venerable old book... Good one... Yeah, I've got that one also as you know.

Actually, I think you are misunderstanding what I'm saying. I'm not saying there is no variability in corrosion rates - what 'm saying is that the basic design is that you should have between 1 and 2 years of protection minimum for a sacrificial anode installation. If you find your boat is in a situation where the zincs that are on it aren't giving you at least that, then put more zincs on. If you think there's a problem with your boat, then at least it's protected while you sort out the problems on our boat. If you think there's a problem in the marina for whatever reasons those may be, same thing - put more zincs on until you can sort it out. Other than space limitations, you can't have too many...

I monitor my boat every year and watch to make sure the zincs look like they are running correctly. I personally like to have at least 3 years of protection just to not have to worry about transient issues... I was in a marina once where there was a huge stray current problem. It took out a number of props on boats around mine, almost took out mine as well. But instead I caught it just as it was finishing off all my zincs... Zincs are a lot cheaper to replace than props...

dj
 
Aug 1, 2011
3,959
Catalina 270 255 Wabamun. Welcome to the marina
There is one upside to Covid, few of the staff will be returning, so we're probably safe. Best to go there and find out as soon as it is safe to do so.
 
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