Zinc Protection on Swing Keel?

[CloudDiver]

I'm wondering what your thoughts and/or experiences are with Zinc Protection installed on your swing keel? Especially those of you who have been sailing extensively in salt water, dry sail or slip kept?

I know I'll be sailing in salt water exclusively, but I'm on the fence about dry sailing/trailer launching. I want to keep my rig up, so I have to find a deal on a Marina where I can trailer launch but store rig up, otherwise I will go with a slip or mooring ball.

But keeping on point, if I install Zincs on the keel I'm more concerned about drilling a hole into the Cast Iron I just worked so hard to seal! To get the electrical conductivity between the keel and Zincs the bolt has to make contact with the base metal, so this rules out using thread sealers. My guess at the best approach to this is using a slight counter bore in the threaded hole just like you would do on deck hardware. Thread the bolt in dry through the first Zinc most of the way and then just take a small coil of Butyl Tape (real small coil) around the treads close the back of the Zinc. This will create that "O-ring" seal around the shaft of the bolt while still allowing the majority of the bolt to remain 'dry' as it threads through the cast iron. Repeat on the other side when you install the 2nd Zinc with nyloc nut. Does this sound like the correct approach?

 

[CapnGrumpyBreeches]

I'm wondering what your thoughts and/or experiences are with Zinc Protection installed on your swing keel? Especially those of you who have been sailing extensively in salt water, dry sail or slip kept? I know I'll be sailing in salt water exclusively, but I'm on the fence about dry sailing/trailer launching. I want to keep my rig up, so I have to find a deal on a Marina where I can trailer launch but store rig up, otherwise I will go with a slip or mooring ball. But keeping on point, if I install Zincs on the keel I'm more concerned about drilling a hole into the Cast Iron I just worked so hard to seal! To get the electrical conductivity between the keel and Zincs the bolt has to make contact with the base metal, so this rules out using thread sealers. My guess at the best approach to this is using a slight counter bore in the threaded hole just like you would do on deck hardware. Thread the bolt in dry through the first Zinc most of the way and then just take a small coil of Butyl Tape (real small coil) around the treads close the back of the Zinc. This will create that "O-ring" seal around the shaft of the bolt while still allowing the majority of the bolt to remain 'dry' as it threads through the cast iron. Repeat on the other side when you install the 2nd Zinc with nyloc nut. Does this sound like the correct approach?

I kept my swing keel in salt water from July until late October this year. I had drilled the keel zinc and established good contact with the keel only by means of a snug fit. It did a good job protecting the keel but I think I will be adding either larger zincs or even a second zinc/bolt to the keel. During haul out, the zinc was almost completely gone. I may take your advice on the butyl tape though that's a good idea

 

[CaptDon01]

Luke....The only place I'm aware of in San Diego where you can keep the boat rigged and on a trailer,(dry sail), and have access to a ramp for launching is Pier-32 Marina in National City,(other than a yacht club like MBYC and SDYC that have cranes). A friend of mine keeps his C-22 swing keel boat in the summer down at Chula Vista in a slip. His zinc's dissolve away in 30 days. He believes there is stray voltage in the water that causes the quick loss of the zinc, I believe it's the salt water, cast iron, bronze, and stainless steel battery hanging below the hull. One thing for sure, if you don't take precautions, your keel will end up looking like mine in the attached photos.

Don

 

[Gene Neill]

Don - how much sailing did it take for that to happen?

I had not previously given any thought to zincs, being a trailer sailor, and only in saltwater for maybe three weeks a year.

 

[CaptDon01]

Gene.....That's the swing keel on my 1988 "New Design" C-22. Best I could tell from the paperwork, she was pretty much in a slip at Marina Del Rey, CA from 1988 to 2005. Beautiful boat from the waterline up. The previous two owners never had the swing keel encapsulated with a barrier coating, no zinc's, and only some occasional bottom paint. She was put on the hard in 2005, and hasn't been in the water since. I never had zinc's on my original C-22, but she was enclusively in fresh water, and I did the required swing keel maintenance. If your only in salt water a few weeks a year, zinc's wouldn't hurt, but the key would be an epoxy barrier coating.

Don

 

[hawk232]

couldn't you seal the threads with di-electric grease? it is conductive but the grease would help to keep water off/out of the keel?

it sure would hurt to drill into that beautiful keel KNOWING that its going to get water in it!!

 

[$tingy Sailor]

I have a blog post on this topic in my queue ready to publish, but it won't be for a few weeks yet, so here's the preview.

The zinc plate on my keel that was screwed into a recessed nut epoxied into the keel fell off easily and the hole rusted out. I'm not going to put a new one back on when I'm done refinishing the keel since I sail in fresh water, but if I were going to be in salt water, I would not mount it to the keel at all. As has been mentioned, there's no reliable and strong way to attach it with electrical conductivity without making it easy for salt water to penetrate and start corroding the keel itself.

Instead, I would do it the way CD recommends for lead keels. That is, mount the zinc on the hull and connect it electrically with a wire to the winch frame, which in turn connects electrically to the keel by the winch cable. The keel stays sealed, the zinc gets attacked remote from the keel, and it's relatively easy to seal the through hole (if any) in the hull for mounting the zinc. Another option would be to use one of the keel weldments and embed it in the hull and attach the wire to the tab on the inside of the hull. Would make replacing the zinc a snap.

 

[allen-deckard]

guess I'll put my 2 cents in here with what I've done.

I'm not saying it's the best setup and I'm sure others have done better but it was the best I could do without major stuff being done and I'm only capable of so much.

I hauled my boat out.

Took it to a local machine shop and with the boat on the trailer had them sandblast the keel the best they could. Yah part of the top of the keel didn't get sandblasted where it's up inside the trunk but it got most of it.

At that point I got a gallon of fiberglass resin and then coated the entire keel that I could get to. Then I painted the entire thing with bottom paint again that I could get it and blobing it up into the trunk best I could.

After all that I got a large zinc plate and drilled threw the bottom of the keel and bolted it on.

After 9 months in salt water thus far I have zero rust. I'm not gonna say it's great and it's gonna last forever but "thus far" it's working and I'm pretty happy.

Yah I know the proper way is to remove the keel and do the same thing but I really had/have anyway of performing the task without taking it to a boat yard and hiring it out. Thing is it would probably cost more than just buying one of the new keels that they make for the new models that are made of lead or just going nuts and forming my own keel of fiberglass and lead which wouldn't really be all that difficult.

Lastly like I said the people I've read on here that really do it right take the keel off and fair the entire thing but that's just not in the cards for me...At this point mine is holding up pretty good and will probably last me for a few years.

 

[Jacktar]

I angle ground the rest spots on my 83 C-22 keel and then covered them with thickened epoxy to match the existing barrier coat (probably epoxy based on how it sanded. Two coats of Trinidad blue SR and sprayed outboard spray bottom paint into any places in keel box i could not reach with brush taped to a stick. Then I took a tap and tapped a threaded hole in one side of the keel near the pivot pin and attached a teardrop zinc with a bolt. This made the electrical connection without piercing through the keel. Will check this year and see how it works, may put a second zinc on other side same way. This way there was no discernible gap between the zinc and epoxy coating. Will post later when I look at it, probably with snorkel when water is warmer here in northwest florida.

 

[Gene Neill]

Gene.....That's the swing keel on my 1988 "New Design" C-22. Best I could tell from the paperwork, she was pretty much in a slip at Marina Del Rey, CA from 1988 to 2005. Beautiful boat from the waterline up. The previous two owners never had the swing keel encapsulated with a barrier coating, no zinc's, and only some occasional bottom paint. She was put on the hard in 2005, and hasn't been in the water since. I never had zinc's on my original C-22, but she was enclusively in fresh water, and I did the required swing keel maintenance. If your only in salt water a few weeks a year, zinc's wouldn't hurt, but the key would be an epoxy barrier coating.

Don

For having spent seven years in the salt, that keel doesn't look too bad! Is it worse in person?

That boat was such a great find. I'm still a little jealous!

 

[CaptDon01]

For having spent seven years in the salt, that keel doesn't look too bad! Is it worse in person?

That boat was such a great find. I'm still a little jealous!

Yes, huge chunks of rusted iron that have either fallen off, of are loose.

Don

 

[CloudDiver]

Stingy, those are two great recommendations and honestly it has me wiping the sweat off my brow knowing I have two other choices besides drilling a hole in my keel! Thanks!

With option #1, The eyebolt in the end of the keel should have its threads sealed with a soft bedding caulk like or Blue Loctite, wouldn't that hinder the electrical conductivity to the cast iron? I can use dielectric grease but that really has little thread-locking effect, but my eyebolt is pretty dang tight when you get it turned down and parallel to CL. I have my new eye bolt threaded in and tightened down dry at the moment and won't seal it until after barrier coat primer.

Option # 2, what is the wire going to, still the winch? Using the weldment, isn't the idea to glass it into the hull with threads going to water so the zinc is on the outside of the hull, or do you mean have the zinc on the inside? Is the zinc more, less, or equally effective when in the bilge rather than in the water?

I have a blog post on this topic in my queue ready to publish, but it won't be for a few weeks yet, so here's the preview.

The zinc plate on my keel that was screwed into a recessed nut epoxied into the keel fell off easily and the hole rusted out. I'm not going to put a new one back on when I'm done refinishing the keel since I sail in fresh water, but if I were going to be in salt water, I would not mount it to the keel at all. As has been mentioned, there's no reliable and strong way to attach it with electrical conductivity without making it easy for salt water to penetrate and start corroding the keel itself.

Instead, I would do it the way CD recommends for lead keels. That is, mount the zinc on the hull and connect it electrically with a wire to the winch frame, which in turn connects electrically to the keel by the winch cable. The keel stays sealed, the zinc gets attacked remote from the keel, and it's relatively easy to seal the through hole (if any) in the hull for mounting the zinc. Another option would be to use one of the keel weldments and embed it in the hull and attach the wire to the tab on the inside of the hull. Would make replacing the zinc a snap.

 

[allen-deckard]

want to put my 2 cents in here and someone else can correct me.

Did electronics and electrical work for 40 years. If it was an electrical connection then I'd have to say no on the lock tight.

However the current that's flowing threw this connection is next to absolute nothing and would take only the absolute smallest of electrical conduct to work in my opinion.

Even with the lock tight I cant imagine unless your threads are extremely wore out that the metal of the bolt isn't making an electrical connection to the keel.

It's a simple test if you have an ohm meter just test it and see what the resistance is by running a separate wire or one leg of an extension cord you have laying around and connect it to the wench then to the keel and see what kind of resistance you have going. My guess is that your gonna have a small amount.

Anyway that's my 2 cents. Well probably 4 or 5 but anyway.

 

[CloudDiver]

Good points Allen. After all the work I did to my Keel I really want to be sure I don't get any water into the base metal, including the treads for the eye bolt. My original eye bolt was just a tad longer and had a split lock washer. When you tightened it down it would be a perfect fit, just shy of bottomed out with the lock washer fully depressed ant the eye bolt on center-line. The new one from CD is slightly shorter and does not have the 'collar' on its shaft to support the use of the lock-washer, so I really need to make sure I Loctite the threads, plus I don't want water in there. So if I can go that way and still have just enough contact to make the electrical connection then I feel good about that.

I do have an Ohm meter, I will have to give this a test. I have plenty of time before I will be applying the paint and locking down the eye bolt for good.

want to put my 2 cents in here and someone else can correct me.

Did electronics and electrical work for 40 years. If it was an electrical connection then I'd have to say no on the lock tight.

However the current that's flowing threw this connection is next to absolute nothing and would take only the absolute smallest of electrical conduct to work in my opinion.

Even with the lock tight I cant imagine unless your threads are extremely wore out that the metal of the bolt isn't making an electrical connection to the keel.

It's a simple test if you have an ohm meter just test it and see what the resistance is by running a separate wire or one leg of an extension cord you have laying around and connect it to the wench then to the keel and see what kind of resistance you have going. My guess is that your gonna have a small amount.

Anyway that's my 2 cents. Well probably 4 or 5 but anyway.

 

[CaptDon01]

Luke....Just remembered about "Campland Marina" at Mission Bay. They have a dry storage lot, not sure if you can take a sailboat rigged from their lot to their ramp.

Don

 

[uncledom]

couldn't you seal the threads with di-electric grease? it is conductive but the grease would help to keep water off/out of the keel? it sure would hurt to drill into that beautiful keel KNOWING that its going to get water in it!!

Di-electric grease is not a conductor it is an insulator.

 

[CloudDiver]

Called twice and left messages about exactly that, still no response.

Luke....Just remembered about "Campland Marina" at Mission Bay. They have a dry storage lot, not sure if you can take a sailboat rigged from their lot to their ramp.

Don

 

[Terry in Naples]

For what it is worth. Here in sw florida in saltwater i am told adding an extra zinc on the shaft will only attract more electrolysis and will not add any more protection. So following this premiss adding 2 zincs will not add any extra protection or last longer than just one.

 

[$tingy Sailor]

CloudDiver,

I agree with Allen-Deckard about conductivity through the eye bolt. It would be almost impossible to completely isolate the bolt with thread sealant of any kind and any significant torque applied. Since it's more important to seal it from salt water ingress and be 100% tight, I'd focus on that and just check for conductivity periodically as he suggested during your regular keel maintenance schedule.

I think you get the idea of the remote mounted zinc. Bedded in the hull with the threads outside the hull and the tab inside. I'd mount it as practically below the winch as possible (but in a thin enough part of the hull) so that it's always in the water and is the shortest wire run to the winch frame (appropriately routed and fastened out of the way).

Screw the zinc onto the outside, drill the tab and attach the wire with a crimped eye terminal, SS screw, lock washer, and nut. I'd seal all exposed metal at the tab attachment in liquid electrical tape so any bilge water doesn't eat up the connection. Crimp another eye on the winch end of the wire and attach to any convenient screw or bolt in the winch frame. Then test for conductivity between the zinc mounting bolt on the outside of the hull and the nearby eye bolt in the keel.

If it's all good, watch as the zinc mysteriously disappears and your keel stays pristine.

This is untried by me, mind you. But you're just the guy to prove it works! I might do it if our trip to the San Juan islands this summer materializes.

 

[CloudDiver]

Stingy Sailor challenge accepted :dance:

Who wants to bet I can do this for less than $20?

CloudDiver,

I agree with Allen-Deckard about conductivity through the eye bolt. It would be almost impossible to completely isolate the bolt with thread sealant of any kind and any significant torque applied. Since it's more important to seal it from salt water ingress and be 100% tight, I'd focus on that and just check for conductivity periodically as he suggested during your regular keel maintenance schedule.

I think you get the idea of the remote mounted zinc. Bedded in the hull with the threads outside the hull and the tab inside. I'd mount it as practically below the winch as possible (but in a thin enough part of the hull) so that it's always in the water and is the shortest wire run to the winch frame (appropriately routed and fastened out of the way).

Screw the zinc onto the outside, drill the tab and attach the wire with a crimped eye terminal, SS screw, lock washer, and nut. I'd seal all exposed metal at the tab attachment in liquid electrical tape so any bilge water doesn't eat up the connection. Crimp another eye on the winch end of the wire and attach to any convenient screw or bolt in the winch frame. Then test for conductivity between the zinc mounting bolt on the outside of the hull and the nearby eye bolt in the keel.

If it's all good, watch as the zinc mysteriously disappears and your keel stays pristine.

This is untried by me, mind you. But you're just the guy to prove it works! I might do it if our trip to the San Juan islands this summer materializes.