incredible corrosion on seacocks

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Steve J.

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Jun 5, 2004
1
-Beneteau Oceanis 321 Sarasota, Florida
Can anybopdy suggest a reason why my two thru-hull fittings have taken on 1/4 inch corrosion over the entire fittings? The color of this corrosion goes from white to pink. These are the original fittings and have never been changed on my oceanis 321 in its 12 years.
My dive guy changes my sacrificial anode every two or three months ( or as he claims, "when necessary" )
Can there be THAT MUCH stray current in my marina?
Also, what replacements thu-hull seacocks are recommended?
 
Don S/V ILLusion

Don S/V ILLusion

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Sep 25, 2008
7,401
Alden 50 Sarasota, Florida
Going through zincs that fast (2-3 months) indicates you have a serious problem more than likely on your boat rather than the marina which is impossible to diagnose via the internet. You should start by going through every single connection on the boat, both AC and DC.
 
Gunni

Gunni

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Mar 16, 2010
5,937
Beneteau 411 Oceanis Annapolis
Do you have an shore power electric system isolator? None of these seacocks should be bonded.
 
C

cuz928

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Jan 13, 2012
4
Beneteau 473 Qld
If you check out yahoo groups beneteau 473 you will find a thread about the thru hull fittings used by beneteau. There appears to be a metal reaction betweem the brass and bronze. If any Beneteau owners here haven't replaced all of their orginal thru hull fittings you are asking for big trouble sooner or later.
Steve J. said:
Can anybopdy suggest a reason why my two thru-hull fittings have taken on 1/4 inch corrosion over the entire fittings? The color of this corrosion goes from white to pink. These are the original fittings and have never been changed on my oceanis 321 in its 12 years.
My dive guy changes my sacrificial anode every two or three months ( or as he claims, "when necessary" )
Can there be THAT MUCH stray current in my marina?
Also, what replacements thu-hull seacocks are recommended?
Click to expand
 
catsailor

catsailor

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Jan 10, 2009
590
PDQ 32 Deale, MD
cuz928 said:
If you check out yahoo groups beneteau 473 you will find a thread about the thru hull fittings used by beneteau. There appears to be a metal reaction betweem the brass and bronze. If any Beneteau owners here haven't replaced all of their orginal thru hull fittings you are asking for big trouble sooner or later.
Click to expand
Bingo. Your describing brass, not bronze. With that much corrosion, your time is limited.
 
M

msade

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Feb 3, 2011
21
beneteau oceanis 440 haifa
Brass is an alloy which contains copper and zinc
Sooner or later the zinc is disintegrating and the thru hull looses its strength
However 3 month period between replacing sacrificial anodes is not usual
It seems you have a shore problem which creates galvanic voltage in your electrical system
The best and immidiate action to take is not to connect shore power untill you solve the problem
 
ph034495

ph034495

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Oct 20, 2012
14
beneteau 42S7 honolulu
just want to add.. I am currently hauled out (beneteau 42S7) and pulled one of the ball valves for a sink drain, during the dismantle the thru hull snapped off, it was a bright copper color on the inside.. started looking at them all. As of today removed eight, all that was required was a tap of the hammer and they would break off at the hull nut... as stated . bad recepie for safety...
 
Maine Sail

Maine Sail

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Feb 6, 1998
11,704
Canadian Sailcraft 36T Casco Bay, ME
ph034495 said:
just want to add.. I am currently hauled out (beneteau 42S7) and pulled one of the ball valves for a sink drain, during the dismantle the thru hull snapped off, it was a bright copper color on the inside.. started looking at them all. As of today removed eight, all that was required was a tap of the hammer and they would break off at the hull nut... as stated . bad recepie for safety...
Click to expand
A lot of the EU branded boats ship with sub standard below water fittings because the "service life" over there, to meet code, is 5 years. If replacing use UL Marine rated bronze by Groco or Apollo. This will be an 85-5-5-5 bronze not a DZR-1 brass or yellow brass... Alternatively you can order Marelon OEM/93 series valves but you'll need to go up one full size on each fitting as they are not "full flow"....

While you are at it I would urge you to install "proper" flanged seacocks and not a valve threaded directly to a thru-hull fitting....
 
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