When I put my CD27 in the water last April, it had a zinc nut (perinut is it) at the end of the propeller shaft and I also put on a brand new zinc on the prop shaft between the prop and the boat. When we took the boat out of the water in November, boat zincs were COMPLETELY gone and the end of the prop shaft look like it had just been polished to a high gloss. My boat was in a slip all season right next to a large 35 foot power boat that had shore power running ALL THE TIME! I'm wondering if stray current from that set up just ate up my zincs? I don't use alot of electronics on my boat. I use the batteries for starting the engine and running the knotmeter and depth sounder. That's all. Do you think it was stray current from that boat or might I have a problem somewhere else?
Thanks,
Warren
Sine Qua Non
cd27 1980 #166
Setsail728@aol.com
Stray Current
Moderator: Jim Walsh
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John Sill
Re: Stray Current
I had an apparently similar problem with zincs disappearing (not quite as fast as you). However, I also had problems with the ground fault circuit breaker popping when I first applied ac shore power. Finally I disconneted the shore power from the boat in the next slip (using constant shore power) and that solved the ground fault for the moment!
That boat moved to another part of the marina at the end of the season and I haven't had a zinc or ground fault problem since. Don't know how you would identify your problem since the evidence occurs slowly. However, maybe an ammeter might do the trick.
Has anyone else tried to identify stray ground problems with an ammeter?
Beholder's Eye
CD 31
jesill@erols.com
That boat moved to another part of the marina at the end of the season and I haven't had a zinc or ground fault problem since. Don't know how you would identify your problem since the evidence occurs slowly. However, maybe an ammeter might do the trick.
Has anyone else tried to identify stray ground problems with an ammeter?
Beholder's Eye
CD 31
jesill@erols.com
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M.R. Bober
Re: Stray Current--two questions
1) How often/how long is shore power connected to your boat?
2) You don't have a galvanic isolator, do you?
Temporary solution (??) get another set of zincs that you can attach with a battery clamp (to your bonded CD grounding system). Use it when you are in the slip. I think a product called "The Grouper" is available.
Good Luck.
Mitchell Bober
RESPITE
CD330
2) You don't have a galvanic isolator, do you?
Temporary solution (??) get another set of zincs that you can attach with a battery clamp (to your bonded CD grounding system). Use it when you are in the slip. I think a product called "The Grouper" is available.
Good Luck.
Mitchell Bober
RESPITE
CD330
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Warren Kaplan
Re: Stray Current--two questions
Mitchell,M.R. Bober wrote: 1) How often/how long is shore power connected to your boat?
2) You don't have a galvanic isolator, do you?
Temporary solution (??) get another set of zincs that you can attach with a battery clamp (to your bonded CD grounding system). Use it when you are in the slip. I think a product called "The Grouper" is available.
Good Luck.
Mitchell Bober
RESPITE
I have NO shore power connected to my boat. Large cabin cruiser in slip next to mine has shore power running ALL the time. I'm moving to a new slip next season and hopefully that will help if stray current is the problem in the first place.
Warren
M.R. Bober wrote: CD330
Setsail728@aol.com
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M. R. Bober
Stray current
Two years ago RESPITE went throught zincs at an alarming rate. I followed Nigel Calder's procedure to attempt to locate the source of the trouble, assuming a stray current aboard. By serially disconnecting all electrical circuits, I found a constant 20 mA flow, which proved to be the "pilot" light for the "battery on" switch. He should mention in the book that this is a normal condition. Seriously I was concerned about a few things: 1) when the shafting was replaced (but that's a another story) the bonding was improperly connected (loosely) to the aft bolts of the shaftlog/cutlass bearing's housing, 2) the battery charger, 3) the bilge pump and submerged switch, and 4) the shore power outlet on the dock.
I reattached the bonding wire. Couldn't prove anything about the battery charger or bilge pumps. Found .6 VAC between ground on the pier outlet and the water (not great), but the dockmaster was unable to improve the circuit. I really tried (it's my pier) but short of adding a grounding stake to a branch circuit (not nice) I was stuck. During the winter on the hard I measured resistance between & among all through hull fittings, the earth and the AC & DC circuits. All were correctly "open".
I installed a galvanic isolator to the grounding cicuits of the ship.
I cannot state with certainty what "cured" the problem, but it seems resolved. It drove me crazy and worried me quite a bit.
Good luck.
Mitchell Bober
RESPITE
CD330
I reattached the bonding wire. Couldn't prove anything about the battery charger or bilge pumps. Found .6 VAC between ground on the pier outlet and the water (not great), but the dockmaster was unable to improve the circuit. I really tried (it's my pier) but short of adding a grounding stake to a branch circuit (not nice) I was stuck. During the winter on the hard I measured resistance between & among all through hull fittings, the earth and the AC & DC circuits. All were correctly "open".
I installed a galvanic isolator to the grounding cicuits of the ship.
I cannot state with certainty what "cured" the problem, but it seems resolved. It drove me crazy and worried me quite a bit.
Good luck.
Mitchell Bober
RESPITE
CD330