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Diving to clean boat bottom

Jan 19, 2010
6,814
Hunter 26 Lake Martin AL
In some areas diving within a marina is prohibited. The reason given is the hazard of stray current due to damaged or possibly improper shore power wiring. There have been at least a couple of fatalities here in Michigan, and with the present high water conditions there is a lot of potentially dangerous wiring that is actually submerged.
My understanding is that this is only a concern in fresh water. At least that is what @fstbttms told me in another thread. Makes sense to me though.
 
Jan 19, 2010
6,814
Hunter 26 Lake Martin AL
Can you offer advice on how to scrape the bottom under water without taking off too much paint? Do you use something like a plastic window scraper that one would use for taking ice off of a car windshield.
I have one of these...
1570727406571.png


I keep it on my boat. Every now and again, I like to sleep at anchor in a cove. I will usually put a cold beer in a coozy and wear a life vest like a diaper and then float around my boat scrubbing the bottom with this brush. I have ablative and I'm in fresh water. This does a great job of knocking the slime off. I can't say how it would work in brackish or salt water environments.
 
Apr 12, 2007
73
Hunter 420 Herrington Harbor South
Thank you Doug! "The reason given is the hazard of stray current due to damaged or possibly improper shore power wiring":plus:
 
May 21, 2004
742
C&C 110 Mt. Sinai, NY
Hi Guys,

Long Island Sound sailor here (same harbor at NYSail). Sailing season is from May - October. I use the boat for casual racing, day sails, and some weekend cruises.

Over the years I have use a number of different bottom paints. Some worked well, others not so much.

Being a cheap sailor, what works for me is:
Paint the bottom with Pettit Ultima SR60. Two coats all around, a third coat on the water line and leading edge of keel and rudder. i use 2 gallons
Sail as often as possible.
Spend the winter in a slip.
Sail the the next season as often as possible
Have the boat hauled out at the end of season two.
In the spring, sand / scrub any remaining paint off and repaint before the boat goes in.

In year one I drive the boat 2-3 times. There will be some light slime that comes off very easily. I just use a dobe pad type scrubber. Very little paint is removed when I clean the bottom. In year two I have to clean the bottom a little more often. By the end of the second season most of the paint has worn away.

Some miscellaneous information:
-On my boat the paint definitely ablates when I sail.
-A friend and I bought a hookah rig. Best investment I ever made. It paid for itself in year one.
-I used to paint every year. What a pain it was / is to sand the bottom. Since the paint is over $200 / gallon I was sanding off a lot a money!
-Other paints used - Pettit Hydrocoat - a single season ablative - worked very poorly. Lots of growth. Cheap to buy. Never used again. Pettit Ultra SSA - better than Hydrocoat but only a single season. For me, Ultima SR60 (or 40) is the best deal.

Barry
 

SG

Feb 11, 2017
1,488
J/Boat J/160 Annapolis
I guess the rationale was cleaning an ablative hull causes more paint to "ablat" if that is even a word. That was not my rule it is what the marina enforces as they are a "green" marina or something like that.
ab·late/əˈblāt/
verb
verb: ablate; 3rd person present: ablates; past tense: ablated; past participle: ablated; gerund or present participle: ablating
  1. 1.
    remove (body tissue) surgically.
    "therapeutic intervention to ablate existing cancer cells"

  2. 2.
    gradually remove material from or erode (a surface or object) by melting, evaporation, frictional action, etc., or erode (material) in this way.
    "drying winds slowly ablate away the ice"
 
Oct 24, 2010
2,105
Hunter 30 Everett, WA
Where live (Puget Sound) it's illegal to clean the bottom in the water. So we try to sail it regularly in summer. In the winter it just sits (in fact due to medical issues for 8 months last year). In the spring a weekend sail and it was clean. Our Micron 66 has given us 3 years. I tried Micron CF (copper free) and it had a full beard in 8 months. Copper free is now mandated for 2021 in Washington. I don't know what we'll do then.

Ken
 
Nov 3, 2018
59
Beneteau Oceanis 35.1 Firth of Tay Herrington Harbour North
Ken: In the Chesapeake Bay area it is illegal to release toxins into the water. So cleaning a bottom that has ablative paint is not permitted. But a bottom with hard paint can be cleaned as the amount of toxin released is no more than when the boat is moving.
 
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May 17, 2004
2,007
Beneteau Oceanis 37 LE Havre de Grace
Ken: In the Chesapeake Bay area it is illegal to release toxins into the water. So cleaning a bottom that has ablative paint is not permitted. But a bottom with hard paint can be cleaned as the amount of toxin released is no more than when the boat is moving.
Do you have a regulation you can cite for that? The best I can find is https://dnr.maryland.gov/boating/Documents/ts2bottompa.pdf which states “Ablative paints should not be cleaned in the water as the scrubbing action will release paint and its associated biocide. If they must be cleaned while in the water, care should be taken to use soft material such as terry cloth.” Not exactly a prohibition.
 
Feb 26, 2011
1,141
Achilles SD-130 Alameda, CA
Do you have a regulation you can cite for that? The best I can find is https://dnr.maryland.gov/boating/Documents/ts2bottompa.pdf which states “Ablative paints should not be cleaned in the water as the scrubbing action will release paint and its associated biocide. If they must be cleaned while in the water, care should be taken to use soft material such as terry cloth.” Not exactly a prohibition.
Your link is for the Maryland Clean Marina Program. This is a voluntary program that marinas can choose to adopt or not. The program's best management practice for in-water hull cleaning states that ablative paints should not be cleaned in the water (although I guarantee there is no data available that can justify why that should be) but again, this is strictly voluntary and on a marina-by-marina basis. It is not state law.

What people (especially those who create water quality regulations) fail to realize is that copper-laden anti fouling paints (hard, soft or otherwise) release their biocide into the water 24/7/365, whether the boat is cleaned or not, and whether the boat is moving or not. And in-water hull cleaning is proven to contribute just a small fraction of the the total copper that enters the water column from anti fouling paints, regardless of the type of paint involved.
 
Last edited:
May 24, 2004
5,942
CC 30 South Florida
Which marina is going to be shamed for non-compliance? It does not matter if it is law or not. Take the boat out to a sand bar and do your own cleaning.
 
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May 17, 2004
2,007
Beneteau Oceanis 37 LE Havre de Grace
Which marina is going to be shamed for non-compliance? It does not matter if it is law or not. Take the boat out to a sand bar and do your own cleaning.
Agree. I think the point is that there’s no law against doing exactly that.