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Old 31-03-2014, 22:05   #1
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Preventing Corrosion on Galvanised Anchors (April 1)

Galvanised anchors eventually suffer some corrosion, especially around the leading edges where the galvanising can be worn away.

There is an excellent solution that significantly delays the corrosion. It involves coating the whole anchor in a thick layer of sunscreen. The high concentration of zinc oxide in these products is more anodic than the underlying zinc in the galvanising. The sunscreen corrodes in preference to the galvanising, protecting the surface and keeping it like new. In addition, the coating acts like a grease, keeping seawater from making direct contact with metal, giving it dual action.

For best results you need a waterproof sunscreen rich in zinc. Fortunately, these tend to be the lower priced products. The SPF 50+ solutions have more of the important zinc.
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Old 31-03-2014, 22:16   #2
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re: Preventing Corrosion on Galvanised Anchors (April 1)

At first glance I thought this was a good joke but when I thought it through, it is probably a good idea!!!

Thanks noelex
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Old 31-03-2014, 22:18   #3
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re: Preventing Corrosion on Galvanised Anchors (April 1)

It is April 1 so be careful out there.
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Old 31-03-2014, 23:51   #4
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re: Preventing Corrosion on Galvanised Anchors (April 1)

Quote:
Originally Posted by Wotname View Post
At first glance I thought this was a good joke but when I thought it through, it is probably a good idea!!!

Thanks noelex
Awww, come on, Geoff! It IS 1 April after all!

BTW, I've heard that hot dip galvanizing your face will save on your sunscreen costs...

Cheers,

Jim

PS Glad you got out on the river!
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Old 01-04-2014, 02:07   #5
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re: Preventing Corrosion on Galvanised Anchors (April 1)

The science behind this is actually quite good. The zinc oxide in sunscreen is micromilled into tiny spheres which in addition act as a kind of body filler in the zinc coating, thickening it where the coating's application wasn't uniform.

Of course the biggest problem is keeping the coating protected, I personally rub a coating of surfboard wax over the sunscreen which is over the galvanising ... the wax provides a stabilising barrier coat with additional waterproofing qualities. I top over both coatings every time I clean the bottom, just as part of my maintenance to-do list.

Mr. Zog's Sex Wax - Wikipedia, the free encyclopedia is strongly recommended!
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Old 01-04-2014, 03:07   #6
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re: Preventing Corrosion on Galvanised Anchors (April 1)

I have some good deals on bulk "pink zinc".
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Old 01-04-2014, 03:15   #7
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re: Preventing Corrosion on Galvanised Anchors (April 1)

A good bright colour of sunscreen is helpful as it makes the anchors visability underwater better. However, pink is not ideal as red light is lost at quite shallow depths.

Avoid any of the scented products my wife was very suspicious when my clothes smelled of perfume after the first treatment. Initially she didn't believe my explanation that I was only attending to the anchor.
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Old 01-04-2014, 03:31   #8
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re: Preventing Corrosion on Galvanised Anchors (April 1)

actually "greasing the anchor" has been around longer than you think.

in old navy terms this was akin to sending a cadet to the stores for a left handed screwdriver or a short screw, a skyhook,some elbow grease.........amongst other difficult tasks for the uninitiated........
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Old 01-04-2014, 03:39   #9
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re: Preventing Corrosion on Galvanised Anchors (April 1)

Be sure to reapply every 2 hours per the sunscreen directions.

Happy April.
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Old 01-04-2014, 03:54   #10
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re: Preventing Corrosion on Galvanised Anchors (April 1)

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Originally Posted by sailorboy1 View Post
Be sure to reapply every 2 hours per the sunscreen directions.
That is for non marine (human) use. On anchors application once a month seems to make a significant difference.

There is also some evidence that UV radiation attacks the the welds. This problem will be seen more following global warming and the hole in the ozone layer. So make sure there is a thick layer of sunscreen around the critical shank/fluke joint.
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Old 01-04-2014, 05:34   #11
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re: Preventing Corrosion on Galvanised Anchors (April 1)

I grasp the idea.

But is zinc in sunscreen (1) in electrical contact with the anchor and (2) available to dissolve into seawater?

Or would the benefit just be from grease physically and electrically isolating the anchor from the seawater electrolyte?

I've had experience of anchoring Led Myne in a river on the W coast of peninsular Malaysia. And discovering that, overnight, anchor and submerged chain turned black. The effect of high mineralisation (tin? area was world's supply of tin for cans a few decades back) was my guess.

Questions:

1. would clamping an old prop shaft anode (an aluminium shaft anode would be lighter than a zinc one and so much less likely to disturb tip-crown balance of anchor) to rode or anchor shaft be better?

2. would greasing anchor with a commercial water-resistant grease, sort of stuff trailer boaties squirt into their trailer wheel bearings, not be (a) less expensive than SPFwhatever; (b) more effective; and (c) less harmful to environment?

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Old 01-04-2014, 05:43   #12
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re: Preventing Corrosion on Galvanised Anchors (April 1)

It really helps keeping the chain rust free. Once a month I empty a bottle of cheap sun block into the chain locker. SPF 45 seems to do the trick. Anything higher gets all clumpy on the chain.
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Old 01-04-2014, 11:16   #13
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Re: Preventing Corrosion on Galvanised Anchors (April 1)

Sorry it was an April 1st joke. I tried hard to come up with a plausible story that was otherwise harmless. I will do better next year.

Thanks for all those that went along with it I am sure Wotname will find a use for the pink sunscreen.

Appologies to anyone taken in. I realise due to the international time differences the joke may not of appeared in the first 12 hours of April 1st which I guess makes me the April fool.
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Old 01-04-2014, 11:33   #14
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Re: Preventing Corrosion on Galvanised Anchors (April 1)

Quote:
Originally Posted by noelex 77 View Post
Sorry it was an April 1st joke. I tried hard to come up with a plausible story that was otherwise harmless. I will do better next year.

Thanks for all those that went along with it I am sure Wotname will find a use for the pink sunscreen.

Appologies to anyone taken in. I realise due to the international time differences the joke may not of appeared in the first 12 hours of April 1st which I guess makes me the April fool.


and here i was thinking that drinking all that Retsina and ouzo in the hot sun had finally turned you into a wombat
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Old 01-04-2014, 19:39   #15
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Re: Preventing Corrosion on Galvanised Anchors (April 1)

Quote:
Originally Posted by noelex 77 View Post
Sorry it was an April 1st joke. I tried hard to come up with a plausible story that was otherwise harmless. I will do better next year.
Oh my! April Fools!...Now you tell me, I just bought up
all the available supply of sunscreen for the next year
in the U.S.A. to use on my anchor and chain.
Disclaimer...I am not responsible if there are no young
bikini clad ladies out sunning themselves this season because of shortages, that will all be on Noelex!
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