Swim platform zinc

[96TL]

Does your swim platform zinc disintegrate? Two seasons in a wet slip and I can still read the model number and brand off mine. My friend has had his 2520 in the water for three seasons and his zinc looks brand new also. I also noticed both mine and his were covered in barnacles. That can't be good. :?:

Anybody else experience this? Is it possible the zinc was bolted right to the gelcoat/paint and is not making metal to metal contact with the swim platform?

I'm going to pull it off and check it out as soon as we get some decent temperatures. Its cold in NY today!

Thanks.

 

[samsims]

Mine looks new after a year. Make sure the zinc has good contact with the bracket. I wouldn't worry unless you Start seeing corrosion on the bracket.

On a similar note the anodes on my trim tabs are almost gone after a year, how have yours held up? If you have replaced them, where did you get them? I can only find rudder anodes in that size, but one of the halves doesn't have the nut, in the anode.

Stacy

 

[DaleH]

Yes, you need FULL CONTACT between the zinc and the parent metal. I go so far as to take the zinc and 'sand' it on crocus cloth in a figure 8 pattern to ensure it sits flush and square up against the metal it is designed to protect.

There are ways to use a multi-meter and perform an electrical check between the zinc anode and the metal it is on (cathode). Salinity of the water and electrical activity will exacerbate the errosion of the zine. At a minimum I would expect to see it discolor to form the white powder and would expect to lose maybe 20% of the material per season. I bet yours was applied over the powder coating on the bracket ... but I hope I'm wrong.

Also not that depending on the bracket and hull weight distribution, your zine 'could be' out of the water some or maybe all. On my '92 hull, the OB bracket isn't fully immersed.

 

[96TL]

I dont have any corrosion on my bracket, buy my friends 2005 has paint/gelcoat peeling from around the engine mounting bolts. This may be the reason.

Thanks for the info Dale.

 

[DaleH]

... my friends 2005 has paint/gelcoat peeling from around the engine mounting bolts. This may be the reason.

No, I'd bet considerable $$ that the paint peeling around the bolt is caused by galvanic reaction , a by-product of and caused by 'unlike' metal-to-metal contact, otherwsie known as dissimilar metals. It should NOT be confused with electrolysis. It is exacerbated in a saltwater environment. No 2 boats or setups will react alike.

One also sees this on fishing reels where a SS screw holds on the sideplate of an aluminum frame/covered reel.

He needs to REMOVE those bolts and coat them liberally with Tef-Gel to isolate and insulate the aluminum bracket (less nobel) from the stainless steel (more nobel) fastener. He should also ADD a 1/4" thick HDPE washer under the SS fender washers so that no SS bears up against the aluminum bracket.

I myself would drill out the hole bigger and fill with thickened epoxy to make a permanent (and waterproof) 'plug' for bolt to pass through, then goop up with 3M 5200.

 

[96TL]

... my friends 2005 has paint/gelcoat peeling from around the engine mounting bolts. This may be the reason.

I myself would drill out the hole bigger and fill with thickened epoxy to make a permanent (and waterproof) 'plug' for bolt to pass through, then goop up with 3M 5200.

You would do that to the aluminum bracket? The epoxy would adhere to it with enough strength to hold up the engine weight?

Can we remove these bolts one at a time and coat them with Tef-Gel without putting a jack on the motor?

Dale, one more thing. Do you have any CP burgees left?

Thanks.

 

[DaleH]

You would do that to the aluminum bracket? The epoxy would adhere to it with enough strength to hold up the engine weight?

Good clarification, I would only do that epoxy plug to the wood-cored fiberglass hull.

I have also used heatshrink on the 'body' of a SS bolt to insulate/isolate it from the parent aluminum it is holding.

Can we remove these bolts one at a time and coat them with Tef-Gel without putting a jack on the motor?

Sure can! Simple and easy to do! One tube of Tef-Gel will last you many boats. On occasion, I have also used that OMC/Bombardier 'Triple Guard' waterproof, synthetic, blue-colored grease I am so fond of.

Dale, one more thing. Do you have any CP burgees left?

You bet! The last few weeks have been a blurrrrrrrr for me ... I am just getting caught on life, work, and other stuff, like CP.

 

[grouperjim]

Now that you mention it, neither my 2320 or my previous 23DV has shown any significant corrosion on that particular zinc. I keep it on a trailer and wash the boat after every use. I have not noticed any corrosion problems anywhere else.

jim

 

[96TL]

Does the Tef-Gel harden up when it cures, or does it remain soft? Would we have to re-apply it every once in a while? I noticed they also have Tuff-Gel too, but it looks like its more of an adhesive.

And where can we source the HDPE washers?

Can you please email me an invoice for a CP burgee? I will PM you my fiancees email. She has a PayPal account.

Thanks!

Dom

 

[96TL]

Dale, I got some pics of the corrosion. I see how I can easily add Tef-Gel and plastic washers to the top bolts, but the bottom bolts are caulked. Would I still be able to do it to those? I see some corrosion around them as well.

And doesnt this mean ALL the swim platform bolts should be treated the same way?

 

[DaleH]

I see no problem with the bottom ones, there's probably enough 'goop' in there to isolate the SS fastener from the aluminum where it passes through.

 

[96TL]

I see no problem with the bottom ones, there's probably enough 'goop' in there to isolate the SS fastener from the aluminum where it passes through.

At first glance I thought the same thing, but if you look at the pic closely you'll see blistering around the bolt.

 

[96TL]

Anyone else suffering from this problem? I went and looked at my boat today, and I can see early signs of the same problem.

Seems strange that it doesn't bother anyone else? :?:

 

[96TL]

I'd like to update this thread. I finally got around to removing the swim platform zinc. Two seasons and it still looked brand new, besides a white powdery layer along the surface.

I took the nut & bolt off and the zinc was still held firmly in place. I had to use a putty knife and a hammer to remove it. It was caulked! And I don't mean a drop of caulk either, almost the whole zinc was covered. Plus it was caulked right to the swim platform paint. That zinc would've lasted for years to come!

The old zinc left a perfect outline for me to sand off all the caulk and paint. I bought a new Campo R-2 and I now have full metal to metal contact. I only caulked the inside half of the zinc inside the bracket.

So anyone who hasn't checked this zinc, definitely should. I guarantee you'll have the same findings I did.

 

[bdgrbu]

Hey, good post. Ive noticed issues with all of the fasteners that secure my bracket to the transom as well as the area around the swim ladder. In my case too, my zinc looks like the original (2003 Parker). Each year, the zinc loses very little, if any, and just gets coated with slime, small barnicles. I just bought a replacement because I figured something wasnt right. After hearing what you found, my guess is that its a simialr situation.

Ive also been reading the post on bottom painting the bracket, and I'll be making some changes there too.

Someone asked about the trim tab zincs, I can tell you mine are almost gone every year when I pull the boat.

Dom

 

[Chop~Chop]

I looked more carefully myself this afternoon...
Indeed, you can see a light colored ring around the edge of the circle.

Bet that ain't bare aluminum; it's getting ripped out this week.
It will be easy to prep the inside of the tub to make good contact.

I suspect the bracket paint should be carefully sanded/ground to bare aluminum in the shape of the zinc?

 

[96TL]

I suspect the bracket paint should be carefully sanded/ground to bare aluminum in the shape of the zinc?

Exactly. When you take off the old zinc it will leave you a perfect outline. I started with a dremel and a small fine grit sandpaper wheel at slow speed, and then finished it up with some 100 grit sandpaper.

 

[Chop~Chop]

Looked more carefully after removing zinc.
I noticed the hole actually looked as if it had been threaded to accept SS bolt.

I Decide to call Armstrong. Their guy suggested to replace as is...Just use a little dab of adhesive sealant around the bolt/thru-hole.

Electrical connection to the tub is made with the spider washer used under the nut inside. Better be sure too, the bolt makes good contact to zinc on the outside.

 

[96TL]

Electrical connection to the tub is made with the spider washer used under the nut inside. Better be sure too, the bolt makes good contact to zinc on the outside.

I wouldn't trust that little star washer to make enough contact by itself. It's pretty small.

We'll see what my zinc looks like in the winter. I'll be sure to update this thread.