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Catalina/Capri 25/250 Sailor's Forums

Catalina 25 Specific Forum

zincs

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stampeder
Master Marine Consultant

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1608 Posts

Initially Posted - 11/17/2004 : 01:08:47

I launched my new to me 1981 SR/SK this weekend in Esquimalt Harbour (Victoria, Vancouver Island) and it was suggested that I install zincs.
I did an search through previous threads but could not find conclusive info on where to install zincs. One of the Old Salts suggested I screw them into my keel, another guy suggested I dangle a 'fish' when at moorage, another said that because I have no serious electronics - that I don't need zincs.
Do I needs zincs and where do I install them?
Thanx in advance from a Newbie still reeling from the excitement of the first sail and the weight of having to decide which expert to believe.

Edited by - on

D Wrate
1st Mate

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38 Posts

Response Posted - 11/17/2004 : 01:32:34

Firstly let me welcome you to the Wonder West Coast. Are you keeping the boat out here permanently?

For what its worth, a zinc of some sort is a must if you have exposed metal in salt water. My hunch would be that you need to establish an conductive route between any metal in the water and the zinc. Eg the keel and the zinc, outboard and the zinc.

If the keel is fully encapsulated by a waterproof barrier, epoxy or the like, then you may be able to get away without a zinc.

I have zero experience with a swing keel in salt water. I have an 34 ft'er fixed keel with inboard in Sidney Harbour. I have two zincs on the prop shaft. and check them on a monthly basis. If they become excessively eroded I dive and replace them...

Hope that helps somewhat, and again welcome!
David

Edited by - on

Steve Milby
Past Commodore

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USA
5932 Posts

Response Posted - 11/17/2004 : 08:48:30

I keep my 1981 fin keel in fresh water, and believe a zinc is necessary on an exposed cast iron keel, even if you don't use a battery on board. For years I had no zinc on the keel and developed bubbles under the keel fairing material every year. It was a big job to re-fair the keel every year.

I drilled two small holes in the keel, tapped them with threads, and installed a teardrop shaped zinc, and have had no bubbles since. I installed the zinc on the port side of the keel about six inches up from the bottom of the keel, where it would be easily accessible for replacement.

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Ed Montague
Captain

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USA
499 Posts

Response Posted - 11/17/2004 : 15:52:15

My swing keel came with two tear drop shaped zincs, one on each side. Whoever installed them drilled and tapped the holes to except stainless machine screws. I believe they are a must!!! If you have a West Marine catalog there is good information about zincs in it. For those of us in fresh water magnezium (sp)is the recommended material for protection.

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stampeder
Master Marine Consultant

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1608 Posts

Response Posted - 11/17/2004 : 17:08:27

David, which marina are you in? My daughter is in Navy Reserves, so I moored the boat at CFSA (cdn forces sailing association)Marina. I'm going to leave the boat there until late spring, then trailer it out to Kootenay Lake. I live in Calgary, so the next I see the boat will be mid December. I would like to sail up to Sidney and would like to know which Marina would be best for a one week moorage in December.

My outboard has a zinc. I'm a diver, and I have a trailer, so I can put a zinc on anytime. I looked at some zincs at West Marine and was told a self tapping screw - into the keel would work.
If I dangle a zinc fish, I suppose I will have to attach it to the correct boat part.

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stampeder
Master Marine Consultant

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1608 Posts

Response Posted - 11/17/2004 : 17:13:39

Thanx Ed & Steve - I think I'll get one of those big round Zincs and thereby have an additional reason to scuba dive. Maybe I can skulk around the marina and retrieve tools and stuff.

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Leon Sisson
Master Marine Consultant

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USA
1893 Posts

Response Posted - 11/17/2004 : 18:48:50

stampeder,

For maybe 7 years I've kept my 1979 swing keel C-25 in salt water year round except when hauled out for maintenance. For zincs, I have a pair of 5" pancakes attached to the keel with stainless steel allen bolts in tapped holes near the lift cable, and a pair of 5" teardrops on the hull near the pivot, electrically bonded to the keel pivot hardware and mast base. I replace all 4 zincs every other year, at which time what's left looks like swiss cheese or moonscape. At the same time, I also replace the keel cable, cable attaching bolt, and pivot hanger bolts. So far, so good.

-- Leon Sisson

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Dave Laux
Captain

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318 Posts

Response Posted - 11/17/2004 : 20:32:52

Any time you have two different metals that are in contact and submerged you need a zinc, or a magneizium (can't spell it either) The zinc should be in close association with the dissimilar metals, ie. attached to one of them. From what Leon is describing above his system may have too much zinc (thats possible) I would cut back one at a time. Epoxy coating can reduce the metal exposed to the water but will consentrate the damage that occures. Dave

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Steve Milby
Past Commodore

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USA
5932 Posts

Response Posted - 11/17/2004 : 22:22:17

<blockquote id="quote">quote:<hr height="1" noshade id="quote">...was told a self tapping screw - into the keel would work. <hr height="1" noshade id="quote"></blockquote id="quote"> I wore out a drill bit drilling two holes in my cast iron keel. You really need to tap the threads in there with a die. I kept the die well lubricated and worked slowly.

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 11/17/2004 : 22:31:09

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Dave Laux
 Any time you have two different metals that are in contact and submerged you need a zinc...
<hr height="1" noshade id="quote"></blockquote id="quote">
Also, if there's stray current in salt water, as if often the case in a marina, then ANY metal is subject to electrolysis--you don't need dissimilar metals. If a zinc is attached to a less-active metal, then the zinc will take the hit ("sacrifice" itself) and the other metal will be relatively protected.

Electronics that are not grounded to something that's in contact with the water are safe from electrolysis. The keel, cable, and winch are not. A zinc on the keel will protect all three.

BTW, self-tapping screws might not do that well in cast iron--you're likely to twist the heads off trying to drive them in. I'd drill and tap. Keep some cutting oil on the drill bit.

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stampeder
Master Marine Consultant

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1608 Posts

Response Posted - 11/17/2004 : 23:35:29

thanx,sounds like good info. I just read the owner's handbook that PO had onboard, it states that 'keel zincs are mandatory in salt water and are recommended in fresh to protect against electrolysis'
Guess I should have listened to expert #11.

Edited by - on

D Wrate
1st Mate

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38 Posts

Response Posted - 11/18/2004 : 16:47:46

I am in North Saanich Marina in Tsehum Harbour. The Sidney North Saanich sailing club has a reciprocal dock there so if you are a member of CFSA they likely have a reciprocal agreement between the two clubs. Check with the reciprocal officer @ CFSA.

I notice you said you are going to trailer to Kootenay Lake. If you install a zinc for salt water it will have to be changed to a magnesium "zinc".

I take it that Kootenay lake will be the more permanent home?

Edited by - on

Dave Laux
Captain

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318 Posts

Response Posted - 11/18/2004 : 19:48:14

Steve,
Taps are the part that cut female threads, dies do male threads. You drill a hole and tap it to put a machine screw into a keel for example. You would use a die to cut threads on a rod to make it into a bolt. Dave

Edited by - on

stampeder
Master Marine Consultant

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1608 Posts

Response Posted - 11/19/2004 : 00:46:25

I saw some zinc fish at West Marine, and had it suggested to me that dangling a zinc fish was a good alternative to a permanent installation. Does anyone have the real poop on this? From what I've heard and read, it would seem to me that a dangled fish would have to make contact with the correct area of the boat.

Dave, my plan is to divide the year between the west coast and one or more interior lakes. The reason I bought a C25 with swing keel on a trailer - is to take advantage of the fabulous lakes in the BC interior in the warm weather, and while still being able to experience the west coast whenever its feasable. We've only sailed this boat for a couple of hours but the Admiral, Executive Officer and I know that this is exactly the right boat for the kind of sailing and vacationing we want to do.

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Steve Milby
Past Commodore

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USA
5932 Posts

Response Posted - 11/19/2004 : 07:45:52

<blockquote id="quote">quote:<hr height="1" noshade id="quote">I saw some zinc fish at West Marine, and had it suggested to me that dangling a zinc fish was a good alternative to a permanent installation. Does anyone have the real poop on this? From what I've heard and read, it would seem to me that a dangled fish would have to make contact with the correct area of the boat.<hr height="1" noshade id="quote"></blockquote id="quote">I would think so, too, but it makes more sense to me to install a zinc and then not have to handle it again until it needs to be replaced.

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D Wrate
1st Mate

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38 Posts

Response Posted - 11/19/2004 : 11:48:44

Well good on ya man, I look forward to seeing you out there!!!

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 11/19/2004 : 20:18:01

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by stampeder
 I saw some zinc fish at West Marine, and had it suggested to me that dangling a zinc fish was a good alternative to a permanent installation. Does anyone have the real poop on this? From what I've heard and read, it would seem to me that a dangled fish would have to make contact with the correct area of the boat.
<hr height="1" noshade id="quote"></blockquote id="quote">
Dangling a "fish" will only help if it has a conductive connection to the other metal that's subject to electrolysis--that is, any metal in the water or with a conductive connection to metal in the water. Just hanging it from a string tied to a cleat will do nothing. Most of us don't have "bonding systems" (connecting all metal hardware) in our boats. On swingers, the keel, cable, and winch are isolated, and generally no other metal is permanently in the water. With cast iron fins, the keel is isolated. Both of these configurations should have a zinc on the keel. Lead wings and fins have no electrolysis issues as long as the outboard is kept out of the water when not in use. Inboards need a zinc on the shaft.

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JoergK
Navigator

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USA
140 Posts

Response Posted - 11/22/2004 : 17:25:43

As said above - swinger in salt water: you must have zincs, preferably two pancakes close to the cable end, mounted with ss machine srews. Drill hole, tap slowly, with oil. No more than two turns forward and then one turn back (you'll break off the tap if you force it faster). Make sure keel metal is exposed where the zinc touches.
Plus - replace cable every two years.

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