I boat in the great lakes (only fresh water) and switched to magnesium
anodes last year instead of zinc. After one season (5 months in the
water) the magnesium anodes are completely shot. They are riddled with
holes and are falling apart. The zinc anodes took years and years to
look this way.
I know that's what's supposed to happen, but is it possible something
is wrong if they deteriorate so quickly? I'm putting a new pair on
this week for this new season, but I didn't expect to have to change
them every year.
By the way, it's a 30 foot cruiser with twin Volvo duoprops so I have
to change 4 anodes total, 2 for each outdrive.

One more thing, someone told me to add a round, disc anode to each
stainless trim tab and that it would work better.

Ideas, comments?

Thanks

Big Daddy wrote:
I boat in the great lakes (only fresh water) and switched to magnesium
anodes last year instead of zinc. After one season (5 months in the
water) the magnesium anodes are completely shot. They are riddled with
holes and are falling apart. The zinc anodes took years and years to
look this way.
I know that's what's supposed to happen, but is it possible something
is wrong if they deteriorate so quickly? I'm putting a new pair on
this week for this new season, but I didn't expect to have to change
them every year.
By the way, it's a 30 foot cruiser with twin Volvo duoprops so I have
to change 4 anodes total, 2 for each outdrive.

One more thing, someone told me to add a round, disc anode to each
stainless trim tab and that it would work better.

Ideas, comments?

Thanks

You have stray current someplace. My dockmate is on his 3rd year with
magnesium (Lake Ontario)

Ask you marina to check for stray electrical current in the water. They
should last longer than a year.




"Big Daddy" wrote in message
oups.com...
I boat in the great lakes (only fresh water) and switched to magnesium
anodes last year instead of zinc. After one season (5 months in the
water) the magnesium anodes are completely shot. They are riddled with
holes and are falling apart. The zinc anodes took years and years to
look this way.
I know that's what's supposed to happen, but is it possible something
is wrong if they deteriorate so quickly? I'm putting a new pair on
this week for this new season, but I didn't expect to have to change
them every year.
By the way, it's a 30 foot cruiser with twin Volvo duoprops so I have
to change 4 anodes total, 2 for each outdrive.

One more thing, someone told me to add a round, disc anode to each
stainless trim tab and that it would work better.

Ideas, comments?

Thanks

"Big Daddy" wrote in message
oups.com...
I boat in the great lakes (only fresh water) and switched to magnesium
anodes last year instead of zinc. After one season (5 months in the
water) the magnesium anodes are completely shot. They are riddled with
holes and are falling apart. The zinc anodes took years and years to
look this way.
I know that's what's supposed to happen, but is it possible something
is wrong if they deteriorate so quickly? I'm putting a new pair on
this week for this new season, but I didn't expect to have to change
them every year.
By the way, it's a 30 foot cruiser with twin Volvo duoprops so I have
to change 4 anodes total, 2 for each outdrive.

One more thing, someone told me to add a round, disc anode to each
stainless trim tab and that it would work better.

Ideas, comments?

Thanks


You are using the correct type of metal.....magnesium is the choice for
freshwater.

Here is some useful information on corrosion, galvanism and electrolysis you
may want to read:

http://yachtsurvey.com/corrosion.htm

http://yachtsurvey.com/corrosion_in_marinas.htm

http://yachtsurvey.com/SternDrive.htm

Yes, I am in fresh water (Lake Erie) exclusively. I'm in a state run
marina and I suspect if I asked them to check for 'stray current' first
they'd laugh at me, then they'd put me on the standard 6 month waiting
list - at which time, my boat would be out of the water for winter
storage! Sorry I'm being sarcastic, but I don't expect much action
from the marina.

Is there a way I can check for stray current?

Also, you say shore power cords in the water can cause a problem? How
close do they have to be?

One more thing, I like to back my boat into the slip so the outdrives
are really close to the shore power receptacles all along the dock. I
wonder if that could have something to do with it?

Thanks, this is interesting.

"Big Daddy" wrote in message
oups.com...
Yes, I am in fresh water (Lake Erie) exclusively. I'm in a state run
marina and I suspect if I asked them to check for 'stray current' first
they'd laugh at me, then they'd put me on the standard 6 month waiting
list - at which time, my boat would be out of the water for winter
storage! Sorry I'm being sarcastic, but I don't expect much action
from the marina.

Is there a way I can check for stray current?

Also, you say shore power cords in the water can cause a problem? How
close do they have to be?

One more thing, I like to back my boat into the slip so the outdrives
are really close to the shore power receptacles all along the dock. I
wonder if that could have something to do with it?

Thanks, this is interesting.


By any chance do you have any aluminum hull boats docked next to or near
you? An example of an aluminum hull is the Marinette.

"Big Daddy" wrote in message
oups.com...
Yes, I am in fresh water (Lake Erie) exclusively. I'm in a state run
marina and I suspect if I asked them to check for 'stray current' first
they'd laugh at me, then they'd put me on the standard 6 month waiting
list - at which time, my boat would be out of the water for winter
storage! Sorry I'm being sarcastic, but I don't expect much action
from the marina.

Is there a way I can check for stray current?

Also, you say shore power cords in the water can cause a problem? How
close do they have to be?

One more thing, I like to back my boat into the slip so the outdrives
are really close to the shore power receptacles all along the dock. I
wonder if that could have something to do with it?

Thanks, this is interesting.


I would report it to the marina management. Inform them that there may be
stray electric fields in the water, and you remember reading where some
teenagers were stunned and drowned because of the electricity. They will
check very quickly. The story about the teens is true.

On 20 Apr 2005 09:15:14 -0700, "Big Daddy" wrote:

I boat in the great lakes (only fresh water) and switched to magnesium
anodes last year instead of zinc.

The new rage is titanium anodes. Try them, they work great.