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Catalina 25 Specific Forum

Zinc placement

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H20boy
1st Mate

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USA
31 Posts

Initially Posted - 10/29/2002 : 11:53:43

I have a 79/swing keel, and need to place zinc's what do you all have to say about the best placements for these? Thanks

Rick Price
"79" 25 swing
Tacoma, Wa

Edited by - on

Douglas
Master Marine Consultant

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1595 Posts

Response Posted - 10/29/2002 : 13:15:36

Hey Rick: I didn't realize you were in Tacoma. Ruth and I have a slip at Foss Waterway Marina ( X Totem ) We will have to get together some time. Raft ups are great with other locals. Do you keep your boat in the water or is she on a trailer ? Its easy to do zinks if she is on the trailer. Where were or are the old zinks located ? or is this a first time install ? Here are a couple of tips. The lagest item to protect isnt so much the keel. Its the pivot pin/bolts and cable assy.
You will want to locate the zink on the keel somwhere between the two. It will need to be closer to the leading 1/3 so as not to get in the way when the keel comes up. Tear drop shape looks ok or you can use the disc. Here is one little trick I learned. Once you drill and tap for the bolt and before the zink goes on put a small "O" ring on the bolt on the thread side between the zink and keel. This will keep water out of the threads area and make the bolt easyer to remove in the future. If you dont want to mess with all that you can purchase a zink fish with bonding line. Clip the wire to your keel cable and hang the fish in the water over the side. Not as efective but will work untill you pull the boat out. If you ever need a hand give me a call. (see profile)

Doug&Ruth
Boatless in Seattle
Tacoma Wa.

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H20boy
1st Mate

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USA
31 Posts

Response Posted - 10/29/2002 : 15:48:36

Actually we were at Day Island, but will be in the waterway after December at Picks Cove. So we will have to meet up. Thanks for the help. Rick

Rick Price
"79" 25 swing
Tacoma, Wa

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H20boy
1st Mate

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USA
31 Posts

Response Posted - 10/29/2002 : 18:15:59

I took a closer look and it appears there has never been a zinc added..so I will follow your advice ...Thanks

Rick Price
"79" 25 swing
Tacoma, Wa

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Douglas
Master Marine Consultant

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1595 Posts

Response Posted - 10/29/2002 : 22:14:13

Picks cove ? I thought they had closed up. Lots of open slips at Foss. 25' slip 150 with power and water.

Doug&Ruth
Triska (Alberg 29)
Tacoma Wa.

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IndyJim
Navigator

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USA
130 Posts

Response Posted - 10/29/2002 : 22:14:49

Okay Skippers Rick, Doug & Ruth,

Sometimes this site makes me paranoid. I know there are no dumb questions, just dumb people who ask good questions...

What are zincs? Do I have them? Do I need them? Will she sink without a zinc? (just kidding on that last one, it rhymed!)

Seriously, I am very curious.

IndyJim
"Itza Dew Sea"
'84 SK/TR

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dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 10/29/2002 : 22:31:23

A zinc is vaht you vahsh your dishes in! <img src=icon_smile_wink.gif border=0 align=middle>

Don Lucier, 'North Star'
Catalina

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dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 10/29/2002 : 22:36:52

From an article on the West Marine website,...

"Zincs"

Sacrificial Anodes and Galvanic Corrosion

Whenever your boat's hull is submerged in water-salt or fresh-there is the danger that various metal components will be eaten away by galvanic corrosion. This chemical reaction occurs when different metals are touching one another or are electrically joined together by a conductor in an electrically conductive fluid (an electrolyte). The least noble metals are referred to as active and are electrically positive in polarity, while the most noble metals are passive and electrically negative.

Sacrificial anodes can extend the life of your boat's hull, engine, rudder, propeller shaft, engine cooling system, refrigeration condenser and other components by protecting them from the deterioration caused by galvanic corrosion. When dissimilar metals are joined together in an electrolyte, the voltage or potential difference between the two causes formation of a galvanic cell in which one metal (the anode) will corrode while the other (the cathode) remains unharmed. Simply put, because anodes-usually zinc or aluminum-are made of a less noble metal than that of the parts they are designed to protect, they corrode instead of the components.

Galvanic self-corrosion can also occur in a single piece of hardware that's immersed in sea water and not in contact with a more noble metal. This happens when electric current flows internally, near the surface, between the bits of the less noble of an alloy's components, for instance zinc, and a nobler, copper component. Because it is less noble, the zinc can be eaten away, leaving a spongy copper residue. That is why it is so important to use marine-grade fasteners in underwater applications, so they are not destroyed, allowing a hose clamp to fail or your propeller to fall off. The higher the salinity and temperature of the water in which your boat floats, the greater the danger that corrosion will occur."

Don Lucier, 'North Star'
Catalina

Edited by - on

IndyJim
Navigator

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USA
130 Posts

Response Posted - 11/01/2002 : 00:19:19

Don,

Thanks for that science lesson. Now I know all about metal nobility. Believe it or not, I understand the entire concept even though I dropped out of physics and chemistry before mid semester (20 years ago).

So, here's my $64,000 question: Just where do you put zincs? I'm trying to picture this. Just imagine me with my head stuck in that cabinet door under my stove or under the sink in the head.

Do I just walk into West Marine and tell the guy I need some zinc?

Even though my humor is pathetic, I'm very serious with my questions. Should this be part of my spring preparation each year?

IndyJim

Edited by - on

dlucier
Master Marine Consultant

Members Avatar

Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 11/01/2002 : 01:20:44

"...Just where do you put zincs?..." - IndyJim

I own a fin keel boat, but the swing keel zincs that I have seen are round, flat zinc discs that are attached(bolted) directly to the sides of the swing keel somewhat near the cable-to-keel attachment point.

"Do I just walk into West Marine and tell the guy I need some zinc?"

I don't know if West Marine would carry this particular zinc, but Catalina Direct sells a swing keel zinc set for $11.50.

Should this be part of my spring preparation each year?

The Catalina Direct Handbook states,

"Keel zincs are mandatory in saltwater, recommended in freshwater to protect this entire assembly from electrolysis. Replace the zincs yearly. Zinc, a less noble metal, corrodes first and protects the iron, stainless steel, and bronze from corrosion."

With that being said, I think it depends if you are in saltwater or fresh. If you are wet slipped or dry. In the water all year or just the summer season. Is there stray voltage leaking at your slip?

Maybe inspecting the condition of the zinc on a yearly basis and replacing it as needed is probably the wisest choice.

Anyone out there with any first hand knowledge?

Don Lucier, 'North Star'
Catalina

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