We are experiencing something strange looking on our keel. See picture. We've been told that it may be something that is seeping through the keel. Has anyone ever seen this? Experienced this?
Strange thing happening to keel
- Thread starter Dunham
- Start date
We have seen some of this over at NYC. It is a particularly hard to remove growth- an algae. Only happens in certain areas of our docks. Don't think it is from inside your keel.
Since you are in Toronto, I'm assuming that you are using VC-17 as a bottom paint on a lead keel.
The problem is likely an AC leak, especially if your boat is bonded and there is connection between the keel and the DC negative system. The AC ground (green wire) should be connected to the DC negative at the common ground on the engine.
Depending on how the boat was wired, the source could be anywhere, chargers, refrigeration, inverters, GFCIs, and so on.
On my boat, with the same symptoms, I found a small 2v AC leak from the AC hot to the engine block, but couldn't find the source of the leak. Several surveyors confirmed the electrolysis/current leak theory. My short term solution was to not connect to shore power and that stopped the problem, didn't cure it.
Carefully check your prop strut, prop, and all metal fittings below the waterline. The leak can leach out metals from those fittings.
It could also be tied to a marina AC problem.
Good Luck. Be sure to post if you find the culprit!
We've tried to scrape off whatever it is.. and it did come off (or at least it looks like it has) Thinking it may be algae that grew on it. But, it's still weird since no other boat at our marina has this problem.
Oh the other thing I should add is - our anode goes every year. Does this happen to you as well??
No. Mines been in Georgian Bay for 6 seasons and 1 on Lake Ontario with original anodes. Could have been replaced last year but will be replacing this year.
Do you disconnect your batteries for the winter?
Yep, we do.
The dealer says that's normal to change it every year. But most of my boating friends don't!
The dealer says that's normal to change it every year. But most of my boating friends don't!
We use a magnesium anode as we are in freshwater. They last about 2 years. Local boaters who use zincs don't replace them very often, which would be expected. Freshwater boats need magnesium or aluminum anodes.