Need New Anode

[Max Schumacher]

I have a Nissan 90 on my 26X and after seventeen days cruising the San Juan Islands this last September, the trim tab/anode under the cavitation plate was forty percent disolved from the seawater environment.
Can anyone suggest a good source as to puchase a new one?
Thanks,
Max

[Duane Dunn, Allegro]

They are usually just stock parts available at any marine store.

I think you may have some other problem however. I've had my Tohatsu in Puget Sound salt water for years now and haven't experienced much change in the anode condition. It gets pitted, but it shouldn't disolve nearly as fast as your's did. It looks pretty much the same as it did when I bought it used 5 years ago.

Our longest trip was 23 days this last summer, over 500 miles, mostly under power from Seattle north through the San Juans, Gulf Islands, across the Strait of Georgia and up Jervis Inlet to Princess Loiusa Inlet, then back. There was no noticable change in the state of the anode during this trip.

[Catigale]

Sounds like you must have stray current from either your DC or AC to eat the anodes up that much. I did my first saltwater trip to Nantucket last summer and it did crap up my zincs but only on the surface.

IF you were moored for any length of time it could have been stray current from a friendly neighbor too, so it might not be anything in your rig.

Catigale

[craiglaforce]

For sure check your charger out. Sounds like you are electrically dissolving the anode with charger current or possibly with a screwed up dock plug. The 120V third wire ground on the charger should be isolated from the boat's 12V negative. You can check out the dock plug with a $5 yellow plug diagnostic tool from radio shack or home store. The thing has lights on it that will indicate if the neutral and ground are reversed for example.

For reference, I think there is a page or two dedicated to this in one of Nigel Calder's maintenance books.

I saw a fellow that had just bought a sailboat and installed a new charger on it that had dissolved all exterior metals in just about a week. it dissolved all 4 thru-hulls, his rudder inside metal, his anodes, etc. This was a traditional keel boat that he used offshore. (he had just sailed the thing up the NJ coast in winter to come to the marina.) Very scary! He could easily have sunk way offshore in the cold ocean. As it was, his rudder broke off as he was leaving the marina.

I am not a fan of electrically bonding fittings on a boat. Nigel discusses the pros and cons involved.

[waternwaves]

Max
As far as the original situation with the anode consumption........

Which marinas did you stay at, and were any of them for multiple days on dock AC??

Secondly, as far as the stray current.........many boats. As Craig noted have the neutral and/or Ground bonded to the 12 Volt ground bus.... This may be hidden inside the generator if you are using a gas or diesal powered generator. IF this is the case. modifications will have to be made to generator. But this is very common on the honda and coleman gensets.. (Most come from the factory bonded together) and can be changed. But the easiest solution is often grounding the genset with an overboard drain with a 3 lb zinc hanging on the end. This will protect the boat and motor quite well........

[mgg4]

...Secondly, as far as the stray current.........many boats. As Craig noted have the neutral and/or Ground bonded to the 12 Volt ground bus....

I have seen texts that suggest, nay almost require, the AC ground to be bonded to the ship's ground (i.e., the same place the 12V neg is grounded); but no where have I seen anyone recommending bonding the neutral to the ships ground. This would be dangerous as it would provide too many paths for current to flow. The shock hazard of using any AC appliance would be much higher.

There is only one place where the neutral and ground should be bonded together, and that is at the source of the current. Normally, this is the AC power company. But, as is the case mentioned below, it can be any source of AC current.

... This may be hidden inside the generator if you are using a gas or diesal powered generator. IF this is the case. modifications will have to be made to generator. But this is very common on the honda and coleman gensets..

It damn well better be common in ALL gensets. For safety sake, the ground and neutral should be bonded at the SOURCE of any AC current, and NEVER anywhere else. If your neutral and ground are not bonded in your genset, then you better bond them right where the neutral leaves the case of the generator. Otherwise your installation is dangerous, and not up to the code requirements of ABYC.

The best way to protect your boat from stray current electrolysis is to make sure you use a ground isolation device (transformer or diode). The transformer will block all DC current, but is heavy and expensive. The diode will block DC current below a certain voltage, but above will allow both DC and AC to pass. This will prevent the stray low-current decay of your zincs and other metals from your shore power connections.

--Mark

[craiglaforce]

From what I understand, small generators do not ground the neutral. They generate the power across the hot and neutral like + and - 55 V rms.
Found this out the hard way, don't ask how. If you ground the neutral on a generator, it will trip the overload even when there is no load applied.

I guess there are 2 schools of thought. "To bond or not to bond, that is the question." I favor "not to bond". But there are pros and cons to either arrangement that should be evaluated by the skipper to see which is best for the specific boat and its environment.

[Moe]

Craig is correct. If you have a Honda EU look at the schematic in your manual. If you don't, look at the EU2000 Manual online.

IIRC, the NEC does not require neutral to be grounded when it comes from an ungrounded (i.e. portable) generator, and electrical devices powered from it are plugged directly into outlets on the generator.
--
Moe

[Max Schumacher]

Thanks for all the unput, Gents,
We have no AC power capability, she's DC only with a second battery which I installed three years ago. Two wetcell deep cycle batts not of the same amp/hr. The smaller is for engine start only and the larger is for the cabin; interior, exterior lights, VHF. Both are run through a battery selector switch, which is set on "both" when charging from the Nissan engine generator. I have had no problem with the trim anode disolving in our fresh water lake, which was nil, as it did in the short time it was exposed to sea water.
Max

[waternwaves]

Mark,
Lest anyone wonder.
my comment was prefaced with:
"
As far as the original situation with the anode consumption........ "


1) I did not identify which wiring configuration does or does not meet AYBC or other codes.. I merely identified where connections exist.
The issue was anode consumption, not miswiring

2) I have observed boats that have been miswired with neutral and ground connected at various locations on the boat, I did not say that it was the proper way

3) Depending on the configuration, Generator sets can be hooked up various ways with common grounds or independently derived grounds...[especially those sets used for instrumentation and control)

AYBC does not specify which is correct. It allows both, based on the needs of the equipment and safety of the operator..


All I was trying to point out was possible connections of stray AC to engine zincs.

The issues of correct or incorrect wiring of a mac with various equipment is covered on other threads. Galvanic Isolation should be standard equipment on a boat with a genset.



I hope this clarifies....