On Thu, 09 Sep 2004 08:06:35 +0200, Meindert Sprang wrote:

"Mac" wrote in message
news

I believe that the effectiveness of a zinc diminishes somewhat as distance
from the protected metal increases. So you probably want to hang the zinc
pretty close to the prop. I'd use galvanized steel wire to suspend the
zinc.

Uhm, what do you think would happen to the zinc coating on the gavanized
wire?

Meindert

Well, as far as the water is concerned, everything in this system looks
like zinc. So in the absence of stray electric fields, there isn't any
strong reason for the galvanization (or anodes) to wear away too fast.

If the electric fields in the water (or time) cause the galvanization
to wear away, then the anode will protect the steel until the anode is
gone. Then the steel will rust. This will be obvious upon inspection, and
can be dealt with by replacing the cheap galvanized wire and adding
another anode.

I specified galvanized wire, as opposed to copper or stainless wire,
because the galvanized wire won't cause the anode to disappear as quickly
as those other metals will. Aluminum wire might work OK, too. But once the
anode is gone, the aluminum might disappear rapidly, and the oxidation
might not be as obvious as rust on steel. I've never used aluminum wire
for anything, so I don't really know what would happen.

Anyway, for similar reasons, never use stainless seizing wire on your
galvanized anchor shackle. Use cheap galvanized wire. The stainless (or
monel) wire some people use actually causes the rode to function as an
anode. Eventually the links near the shackle will rust, long before the
rode as a whole needs regalvanization.

--Mac

Hi,

As a diver who replaces zincs and cleans bottoms among other jobs I will
tell you to get someone to dive your boat and put the zincs on the shaft and
any other places that are at risk. Too often I see boats that have not been
protected and it gets rather costly to repair the damage.

Diving in warm clear water must be nice, I haven't done it in years.

Brian

On Thu, 09 Sep 2004 12:58:19 -0700, Brian Combs wrote:

Hi,

As a diver who replaces zincs and cleans bottoms among other jobs I will
tell you to get someone to dive your boat and put the zincs on the shaft and
any other places that are at risk. Too often I see boats that have not been
protected and it gets rather costly to repair the damage.

Diving in warm clear water must be nice, I haven't done it in years.

Brian


Me neither. ;-(

--Mac

Risk analysis ..... what can go wrong, what are the consequences. Then
what are the costs?

Given that we are talking about a boat where the potential for things to go
wrong is .... words fail me, and the consequences of and cost of
rectifying them when they do is .... again words fail me ..... I'd have the
fish-on-a-wire there right now, and be looking for the diver to put on the
real zinc as well.

David
( who was bitten by electrolysis recently and is going to buy a reference
electrode so he can check the level of protection the zinc every few months
.... when he gets around to it. Do as I say, not do as I do? )





"Jonathan" wrote in message
...
Because of a miscommunication with the yard, my Alberg 35 was relaunched
after a haulout for bottom painting without replacing the zinc. I had
taken the old one off (not much left).

Years ago I had a friend drop a fish shaped zinc overboard every time he
came back to his slip. It was supported on a line for the weight, and a
wire from the zinc to....actually I don't remember what it was to, but I
think it was the green wire grounding system on the boat.

If I adopt a similar plan, attaching a wire to the zinc that did not get
mounted and attaching the other end to engine block or shaft, will this
suffice sufficiently until my next haul out? which will not be until 2006
probably....

I am concerned as the boat had been in since August 2002, and the zinc on
it was almost completely gone. The boat spends May thru October on a
mooring then November through the end of April at the dock for the winter.

Thanks,

Jonathan
--
I am building a Dudley Dix, Argie 10, for my daughter. Check it out:
http://home.comcast.net/~jonsailr