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Post by Ditchcrawler on Dec 5, 2016 12:39:43 GMT
It wouldn't work unless you scraped the blacking off where it attaches and even then it would be hit and miss. It needs to be electrically bonded to the hull in order to work. I don't see why a big earth wire to an earthing point wouldn't be as good as direct contact ....... after all that's what you do on a wooden or GRP boat I think that would work as the circuit would be from the anode through the earth wire into the steel hull and then back to the anode through any bare bits of hull within the anodes protection range.. This answer may change as its had all of one and a half minutes thought.
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Post by Deleted on Dec 5, 2016 13:32:32 GMT
Think the Mg is Magnesium.
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Post by Deleted on Dec 5, 2016 13:37:43 GMT
Think the Mg is Magnesium.
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Post by IainS on Dec 5, 2016 17:16:48 GMT
I noticed that a couple of old tugs which were at Canary Wharf Until recently had anodes hanging on stainless wire with crimp rings and bolted to the vessel side deck. I put a topic about it on cw a while ago - I think they were something to do with it being a different water quality forgotten the word but its when its not fresh water but not saltwater its half way. Or summit. Quite common for ships which are in port for a while, when they are not allowed to use the ICCP (Impressed Current Cathodic Protection) system. Also if zinc anodes are fitted, and the vessel is not in salt water, aluminium or magnesium ones can be temporarily attached by cables as above.
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Post by cuthound on Dec 6, 2016 13:43:12 GMT
I have often wondered why an underwater rubbing strafe made of magnesium isn't used. It could be bolted to the hull every 6 feet.
This would provide full length protection for the hull and couldn't be accidentally knocked off, unlike centre anodes.
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Post by Deleted on Dec 6, 2016 14:14:35 GMT
Its a very interesting idea but I just wonder how it could be fitted securely enough to the hull plating to work as a rubbing strake.
Bolted every 6 feet means there would be 6ft of completely unsupported soft metal. I'm sure that would be prone to damage.
I'd have thought every 6 inches would be more appropriate but that would be a lot of agro
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Post by PaulG2 on Dec 6, 2016 19:21:55 GMT
Yes Brackish is what I was thinking of. Interesting about the props. I noticed the other day there is an old river Lea tug on the bank at Cody dock near canning town and it looked like a cast iron prop. I didn't stick the magnet to it. Perhaps it was bronze but had over time had steel deposited onto it by galvanic action ? Or like the stones song, painted black! Rusty, Rusty, Rusty..... It's "Paint IT Black"! Such sacrilege. and from a Britt to boot.........
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Post by JohnV on Dec 6, 2016 19:29:11 GMT
Or like the stones song, painted black! Rusty, Rusty, Rusty..... It's "Paint IT Black"! Such sacrilege. and from a Britt to boot......... Post count looking good Paul
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Post by cuthound on Dec 6, 2016 19:34:58 GMT
Its a very interesting idea but I just wonder how it could be fitted securely enough to the hull plating to work as a rubbing strake. Bolted every 6 feet means there would be 6ft of completely unsupported soft metal. I'm sure that would be prone to damage. I'd have thought every 6 inches would be more appropriate but that would be a lot of agro It could be mounted (cast? ) into a steel channel to proxide mechanical strength, and the channel bopted to the hull.
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Post by Deleted on Dec 6, 2016 19:47:32 GMT
That's an idea but (and I don't know much about it) I think there is something to do with a "line of sight" with anodes where they only work locally do if one was encased in a channel section it might make it less effective.
I like the idea of it.
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Post by Deleted on Dec 6, 2016 19:51:38 GMT
View Attachmentwhat would be the volt drop on an unknown current flowing between the earthing point used and the point on the hull where the corrosion would be happening if you didn't have the anode bonded by a bit of wire to somewhere on the boat. Use words of no more than two syllables, answers by end of lesson on no more than 3 sheets of foolscap. (in passing explain crevice corrosion ) Β Crevice corrosion effects stainless and alloy steels so boats made out of recycled bean cans and old Vauxhall Viva's will be OK
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Post by Deleted on Dec 6, 2016 19:52:21 GMT
Or like the stones song, painted black! Rusty, Rusty, Rusty..... It's "Paint IT Black"! Such sacrilege. and from a Britt to boot......... How about Ruby Ruby Ruby By the Kaiser chefs. At the very least it may get you to 997!
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Post by JohnV on Dec 6, 2016 19:52:30 GMT
Its a very interesting idea but I just wonder how it could be fitted securely enough to the hull plating to work as a rubbing strake. Bolted every 6 feet means there would be 6ft of completely unsupported soft metal. I'm sure that would be prone to damage. I'd have thought every 6 inches would be more appropriate but that would be a lot of agro It could be mounted (cast? ) into a steel channel to proxide mechanical strength, and the channel bopted to the hull. Just did some very rough calculations and I reckon if you had a 15 metre strip 50mm wide 20mm thick on each side of the boat the metal alone would cost a grand
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Post by Deleted on Dec 6, 2016 19:53:18 GMT
View Attachmentwhat would be the volt drop on an unknown current flowing between the earthing point used and the point on the hull where the corrosion would be happening if you didn't have the anode bonded by a bit of wire to somewhere on the boat. Use words of no more than two syllables, answers by end of lesson on no more than 3 sheets of foolscap. (in passing explain crevice corrosion ) Β Crevice corrosion effects stainless and alloy steels so boats made out of recycled bean cans and old Vauxhall Viva's will be OK I had crevice corrosion last time I went up the beach
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Post by Deleted on Dec 6, 2016 19:55:00 GMT
Crevice corrosion effects stainless and alloy steels so boats made out of recycled bean cans and old Vauxhall Viva's will be OK I had crevice corrosion last time I went up the beach Sounds painful! Was it any better going back down?
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