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Catalina/Capri 25/250 Sailor's Forums

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Water ballast valve sacrificial sinc

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zeil
Master Marine Consultant

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Canada
1317 Posts

Initially Posted - 05/01/2011 : 19:48:33

This is how the sacrificial sinc, attached to the water ballast valve, looks like after only 5 weeks in salt water. It received somehow from somewhere lots of direct hits...

Wonder how to protect the bronze turning ball and under water center board up-haul mechanism after the installation of a Vectran non conducting up-haul cable...

Henk & Johanna
"Floating", a few off your "barnacles".
"Someday Lady" '95 C250WB #151 ('03 - 2016)
"Sea ya" 30ft Bayliner (04-2018 - 09-2018)
"Mariah" '96 C250WB #191 (05-2019 - 15-05-2023)
"Lady J" '00 C250WK #499 (05-2021 - 09-2022)

Edited by - zeil on 05/01/2011 19:50:27

Dave5041
Former Mainsheet Editor

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USA
3758 Posts

Response Posted - 05/01/2011 : 20:29:32

That is pretty aggressive corrosion. If your system has a path to a common ac-dc ground, not unlikely with saltwater in the ballast tank, stray current in the marina would be a real possibility. There is no way to check for stray current since you have left the marina, so the point would be moot. Bronze is very high on the nobility scale, so I would probably check it but not expect to see any damage. A Vectran cable would certainly isolate the parts with greater flexibility and comparable strength but greater susceptibility to abrasion. The zincs are cheap and obviously doing their job, and I would just be happy with that and that your centerboard doesn't weigh 1500 pounds.

Edited by - on

britinusa
Web Editor

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USA
5404 Posts

Response Posted - 05/02/2011 : 03:24:58

Henk, I was not aware that the WB valve had a zinc! I removed our WB Valve a couple of years ago to repair / upgrade the hump. There was no zin anywhere to be seen

Paul

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zeil
Master Marine Consultant

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Canada
1317 Posts

Response Posted - 05/02/2011 : 16:40:15

Just to see if there would be any electrolysis attacks to the metal water ballast valve arrangement I wound & taped a heavy gauge wire to the top of stem of the valve (inside the valve housing) and together with a line suspended it over the side for the 5 weeks while in Mission Bay, CA.

By the way we filled the ballast tank with fresh tap water, it took nearly 2 hours using the air-vent hole and plenty of burping

Charlie owner of Sea Angle (Mission Bay, CA) reported awhile back on this forum that his WB valve nearly fell off and wonder if this could be due to electrolysis attacking the welds and/or parts of the metal.

Sure glad the center board is not heavier and sincs are inexpensive but... how would one protect the turning ball, block and eye of the center board located in the boat's trunk when using a non-conducting Vectran cable... or... perhaps just don't worry about it?

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Dave5041
Former Mainsheet Editor

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USA
3758 Posts

Response Posted - 05/02/2011 : 17:08:38

I probably wouldn't be concerned beyond an annual inspection. I use zincs on my iron keel and I have had no corrosion issues anywhere in the system yet, but the system is conductive from the pivot assembly to the winch. If the WB's centerboard isn't metal, a clamp on zinc near the CB attachment on a stainless cable would connect and protect the entire system. My personal preference would be to go the connect and protect route instead of trying to isolate the components because you would have the zinc as an indicator. I would also keep a zinc attached to the pump system or electrically tie the the pump system to the lift system and protect the whole thing.

Edited by - Dave5041 on 05/02/2011 17:17:37

britinusa
Web Editor

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USA
5404 Posts

Response Posted - 05/02/2011 : 17:30:25

Dave B. in the later model 250 WB's, the cable is vectran. True, it's attached to the CB via a stainless shackle.

Not sure what you refer to when you mention 'the pump system'. Are you referring to the head (ie. not the porta potti)

Paul

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Dave5041
Former Mainsheet Editor

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USA
3758 Posts

Response Posted - 05/03/2011 : 07:26:07

I meant the valve system. I am not familiar with the components of the WB and am only offering general approaches to corrosion control. In general, the metals, especially different metals, need to be either electrically isolated or tied together and protected with a zinc as finding ways to protect each fitting would be challenging. Welds and alloys contain different metals and will often sacrifice the less noble components even when isolated from all other metal parts. If the turning ball, pin, and supporting through hull are all bronze or stainless, then there isn't likely to be a problem. I would be inclined to regularly inspect and protect the valve if there are reports of failure. Another thing to keep in mind is that if you add a zinc to an isolated, bronze fitting, you have created an active cell and the zinc will corrode even though the noble fitting didn't need the protection to begin with. I protect my keel because it has a bronze pivot assembly, iron keel, stainless lifting components, and a galvanized winch - I could almost use it to charge my batteries.

Edited by - Dave5041 on 05/03/2011 07:34:10

britinusa
Web Editor

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5404 Posts

Response Posted - 05/03/2011 : 07:54:14

Thanks Dave, thorough explaination.

I'm pretty sure the turning ball is brass/bronze and the pivot is stainless.

the Keel pivot is bronze ( I have inspected ours before) but the keel is fiberglass.

The issue with welds is appropriate.

The amount of time the boat is kept in the water is also relevant, in our case, we keep JD on the trailer except for about 5 days a month when she is in the water.

The good news is that the WB Valve is easily inspected when the boat is on the trailer!

Paul

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The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.