"hot" mooring? - zincs

[sailorboy1]

I was surprised on haul out this year that my shaft zinc was basically gone and my prop zinc showed some good loss.

The boat was on a mooring all season, never had shore power plugged in the past year and was only at a dock for 1 week at beginning of the year.

I had the same problem last year and was blaming a bad ground connection on the fuel tank (I never proved this as I replaced the boat but that boat also never was connected to shore power). But this boat is different this year so it isn't a boat issue I believe. So 2 years in a row on the same mooring with 2 different boats my zinc went a lot faster than I would have expected.

Is it possible there is a power cable etc running under the boat that could be causing this? Only 1 live aboard boat anywhere near me in the mooring field, but could another boat in the field be an issue somehow? Would hanging a large zinc off the boat connected to the grounding system be worth anything as to helping?

[SteveT]

I don't know if it would help but can't see it would hurt either and hanging a large zinc would be an easy way to see if something was attacking your anodes as you could just pull it up and have a look?

[Blue Stocking]

Don,

There is a shallow bay here in Bermuda where all the old TransAtlantic telephone lines come ashore. The mooring chains there, and the boat zincs, loose material within weeks of being replaced.

[sailorboy1]

Guess I should ask the boats around me next season how thier zincs are doing.

Will an extra zinc over the side make difference in making the regular installed zincs last longer? I would think it wouldnt make any difference to the shaft and prop zincs as that extra overside zinc isn't going to to stop the current going into the shaft.

[fstbttms]

Originally Posted by Don Lucas

Will an extra zinc over the side make difference in making the regular installed zincs last longer? I would think it wouldnt make any difference to the shaft and prop zincs as that extra overside zinc isn't going to to stop the current going into the shaft.

Many boaters fail to understand that for an anode to work, it must be in direct electrical connection with the item being protected. Just hanging a zinc over the side does nothing. Hanging it over the side but terminating the inboard end on the prop shaft may provide additional protection.

[captainKJ]

have u checked the chart to see if any cables are close by ?? most likely not since it is an anchorage but you never know,,,,,just some advice from the subway worker,,,, hey are you close to any government test programs areas???? they might be trying some new electrical ray gun for alien defense,,,,that would explain the electrical problem

[sailvayu]

Most boat owners blame outside sources for the problems that almost always turn out to be on there own boat. It is highly unlikely that there is no outside source causing this problem. Also most owners believe that AC power is the source of galvanic corrosion, this also is almost never true as it takes by far more ac current flow than DC flow to cause problems. Check the thread out here http://www.cruisersforum.com/forums/...-do-73924.html

Some of this info may help you. Also the fuel tank bonding wire has nothing to do with corrosion control it is there to prevent static sparks from igniting the fuel.

Look on your boat first and rule out problems there first, then look for outside sources.

[capn_billl]

I'll have to go with Sailvayu on this one. The odds of an external source for stray current on a mooring field is in the lottery ticket range.

Start with the batteries, and work from there. Any stray wire in the bilge, or any malfunctioning electrical device can be the culprit.

You say this happened to two boats? Anything you brought from one boat to the other? Your favorite toaster? chartplotter? Boombox?

Any bad habits you have, IE disconnecting the battey from the neg instead of the pos? Dropping loose wires into bilge?

A coincidence, both boats have same problem? Bad bilge pump? (a damaged wire submerged in bilge water from bilge pump is a common cause).

[fstbttms]

Originally Posted by sailvayu

Most boat owners blame outside sources for the problems that almost always turn out to be on there own boat. It is highly unlikely that there is no outside source causing this problem.

Originally Posted by capn_billl

Bad bilge pump? (a damaged wire submerged in bilge water from bilge pump is a common cause).

The owner of this prop was convinced the powerboat next to him was the source. Turned out to be a bad spot in the insulation of a bilge pump wire.