Joe wrote:


Again, here in this marina the average voltage in the water is .5
volts DC.
If your marina is of any age the discarded metal in the water can
create stray voltage.

Joe

Hi Joe,

Nick is measuring a voltage between his
hull and his negative wiring, with the
battery and AC power disconnected! It is
hard to attribute that to the water.
That's like measuring a voltage between
the water and the air.

Chuck

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Wilbur Hubbard wrote:


You people and your dumb metal boats, the problems you cause. To make a
battery one needs two dissimilar metals and salt water. You have that in
abundance in a marina what with aluminum hulls, steel hulls, various
zincs, bronze fittings, stainless steel fittings, copper paint, etc.
Steel boats are a menace because steel acts as a cathode so you have to
have all these sacrificial anodes (zincs) attached to protect it from
slowly being eaten away and plated on more noble metals.

Would you allow somebody to pull into the slip next to you and commence
to start sandblasting your hull? I doubt it, but that's about what is
happening to your boat's bottom and sundry metal fittings when a steel
boat parks its ugly ass next to your superior and inert fiberglass boat.
Marinas should be required by law to install active cathodic protection
and all metal boats should pay enough more for their slips to pay for
the costs associated with the protection.

Wilbur Hubbard

Hi Wilbur,

The steel boats that can cause problems
are the larger ones using impressed
current cathode protection. These guys
create a very strong electric field in
the vicinity of their vessel that can be
very difficult to protect from.

But the ordinary steel hulls (the
smaller guys you see in marinas)
shouldn't cause any more problems than
fiberglass or wooden boats using iron
keels with welded anodes. Which is
really no problems at all.

The biggest danger from other boats in a
marina is when they are un- or
under-protected and use shore power. But
even that can be easily dealt with.

Of all the things to complain about,
Wilbur. ;-)

Chuck

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On May 20, 1:39 pm, Chuck wrote:
Joe wrote:

Again, here in this marina the average voltage in the water is .5
volts DC.
If your marina is of any age the discarded metal in the water can
create stray voltage.

Joe

Hi Joe,

Nick is measuring a voltage between his
hull and his negative wiring, with the
battery and AC power disconnected! It is
hard to attribute that to the water.
That's like measuring a voltage between
the water and the air.

Chuck

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That is weird, has to have a short to ground somewhere then.

Where do you think it is coming from?

His engine is grounded to the hull, he can claim it is not all he
wants to. Even if he has a flex joint in his shaft he has a steel
exhaust, which carries water through the flex joints and retains
enough moisture to cause a flow of electrons.

And IMO his engine should be grounded to the hull.

My guess is it's in the water, and at .6 V DC it not an issue, it's
normal.

Nick should measure a few slips in is marina. I had a big crewboat
here that had a rat's nest of wires so the owner of the crewboat & I
mapped the voltage in the whole marina. I wanted to make sure he was
not going to cause problems as he restored the boat.

On average it was .5 volts DC. We mapped the area and watched it over
time to see if anything changed, we cut the power to this side of the
marina completely and still had the voltage.

Joe

Joe wrote:

That is weird, has to have a short to ground somewhere then.

Where do you think it is coming from?

His engine is grounded to the hull, he can claim it is not all he
wants to. Even if he has a flex joint in his shaft he has a steel
exhaust, which carries water through the flex joints and retains
enough moisture to cause a flow of electrons.


I think something like that may be what
is happening, Joe. Two pieces of metal
in contact with some bilgewater or
cooling water could easily show a small
voltage between them.

Chuck

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On May 21, 5:05 am, Chuck wrote:

I think something like that may be what
is happening, Joe. Two pieces of metal
in contact with some bilgewater or
cooling water could easily show a small
voltage between them.


After sleeping on it, I have another suggestion. It may be the bottom
paint he's using. Might be high in copper content. Could cause the
blistering of the paint and the barrier as he described, and in the
fashion it is occuring.

Joe


Chuck

Joe wrote:
On May 21, 5:05 am, Chuck wrote:

I think something like that may be what
is happening, Joe. Two pieces of metal
in contact with some bilgewater or
cooling water could easily show a small
voltage between them.


After sleeping on it, I have another suggestion. It may be the bottom
paint he's using. Might be high in copper content. Could cause the
blistering of the paint and the barrier as he described, and in the
fashion it is occuring.

Joe


Chuck

Well, good ideas but my bilge is dry, so no bilgewater. I checked the
bilge pump by disconnecting it just in case.

The antifouling is Micron Extra which is indeed a copper based paint
though it is supposed to be OK for steel.... but I guess that's open to
interpretation. The steel was originally primed with two layers of
different primer then painted over with an epoxy paint before the
antifouling. As I bought the boat used, I cannot say how well it was
done, but from what I have been able to see while working on it, it
looks to have been done well...

I also considered the engine cooling water issue (actually my wife kind
of steered me there with a question about the different metals in the
cooling system - scary I know..). I broke the circuit if you like by
removing a section of the pipework between the hull inlet and the
engine. The exhaust is the rubber pipe with a plastic waterbox baffle
that exits above the waterline. So, that shouldn't be the cause. There
are only a few items that are mounted on the hull, such as the
instruments so they will be next on the disconnect list.

One good thing is that I did discover that one of my main battery leads
was chafing badly against an engine mount and I have been able to move
this before it became a problem...

Again thanks for the suggestions and I'll keep looking. It's going to
be a weekend job now as the boat is back at it's home marina which is
over an hour's drive from home. I'll certainly post any progress as who
knows, it might help someone else down the track.

Cheers,
Nick.

On May 22, 4:06 am, nick wrote:
Joe wrote:
On May 21, 5:05 am, Chuck wrote:

I think something like that may be what
is happening, Joe. Two pieces of metal
in contact with some bilgewater or
cooling water could easily show a small
voltage between them.

After sleeping on it, I have another suggestion. It may be the bottom
paint he's using. Might be high in copper content. Could cause the
blistering of the paint and the barrier as he described, and in the
fashion it is occuring.

Joe

Chuck

Well, good ideas but my bilge is dry, so no bilgewater. I checked the
bilge pump by disconnecting it just in case.

The antifouling is Micron Extra which is indeed a copper based paint
though it is supposed to be OK for steel.... but I guess that's open to
interpretation. The steel was originally primed with two layers of
different primer then painted over with an epoxy paint before the
antifouling. As I bought the boat used, I cannot say how well it was
done, but from what I have been able to see while working on it, it
looks to have been done well...

I also considered the engine cooling water issue (actually my wife kind
of steered me there with a question about the different metals in the
cooling system - scary I know..). I broke the circuit if you like by
removing a section of the pipework between the hull inlet and the
engine. The exhaust is the rubber pipe with a plastic waterbox baffle
that exits above the waterline. So, that shouldn't be the cause. There
are only a few items that are mounted on the hull, such as the
instruments so they will be next on the disconnect list.

One good thing is that I did discover that one of my main battery leads
was chafing badly against an engine mount and I have been able to move
this before it became a problem...

Again thanks for the suggestions and I'll keep looking. It's going to
be a weekend job now as the boat is back at it's home marina which is
over an hour's drive from home. I'll certainly post any progress as who
knows, it might help someone else down the track.

Cheers,
Nick.- Hide quoted text -

- Show quoted text -

Next time you pull her get rid of the copper based antifoulant and go
with an ablative bottom paint.

I've done about 30 bottom jobs on steel from my 42 fter to 225 fter.
Here is what I suggest. Take it down to bare steel, coat with
Endsallrust a dow chem rust converter you can get it from Hillmans
marine in Texas. Then two barrier coats, most any good quality 2 part
epoxy. Then 2 coats of ablative bottom paint. You need to make sure
all paint is applied with zero moisture on the hull, never let the
bare steel sit overnight, and try to paint on a day with less than 20%
humidity. My last bottom job lasted 5 years.

The only way better is to have the hull flame sprayed or met coated,
then the barrier then the antifoulant.

Good luck.

Joe