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Old 11-10-2016, 11:08 AM   #1
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Underwater Shaft Anode Replacement Video

https://youtu.be/23hY09VA314
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Old 11-10-2016, 12:44 PM   #2
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Interesting.

I've been under boats a number of times for repairs, etc. It's a bit more challenging to do it without a tank......
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Old 11-10-2016, 01:05 PM   #3
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Interesting.

I've been under boats a number of times for repairs, etc. It's a bit more challenging to do it without a tank......
I'm using a hookah in the video. I would consider it unprofessional to do this work without surface supplied air. Or to do it while wearing a tank.
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Old 11-10-2016, 02:48 PM   #4
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I'm using a hookah in the video. I would consider it unprofessional to do this work without surface supplied air. Or to do it while wearing a tank.
Unprofessional to use a tank?
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Old 11-10-2016, 02:57 PM   #5
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Yes. I consider it unprofessional to wear a tank under a boat. Too much potential for damage to occur. Tanks should be left topside and used with a long hose, IMHO. This is known as a "SNUBA" rig.
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Old 11-10-2016, 03:37 PM   #6
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Yes. I consider it unprofessional to wear a tank under a boat. Too much potential for damage to occur. Tanks should be left topside and used with a long hose, IMHO. This is known as a "SNUBA" rig.
Wow, now THAT is an angle I have never thought of when it comes to diving. hmmm
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Old 11-11-2016, 10:25 PM   #7
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If you bond your shafts using shaft brushes, shaft anodes can be eliminated. I made my own shaft brushes which work well. I verify my single (stern mounted aluminum diver's plate) anode's performance using my silver-silver chloride half cell.
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Old 11-12-2016, 04:24 AM   #8
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If you bond your shafts using shaft brushes, shaft anodes can be eliminated. I made my own shaft brushes which work well. I verify my single (stern mounted aluminum diver's plate) anode's performance using my silver-silver chloride half cell.
Most shafts are bonded with or without brushes.
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Old 11-12-2016, 04:27 AM   #9
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Wow, now THAT is an angle I have never thought of when it comes to diving. hmmm
Neither apparently have all the bottom cleaners/prop changers that use tanks.
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Old 11-12-2016, 04:37 AM   #10
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Yes. I consider it unprofessional to wear a tank under a boat. Too much potential for damage to occur. Tanks should be left topside and used with a long hose, IMHO. This is known as a "SNUBA" rig.

What sort of damage? Other than convenience, I wouldn't have thought the two approaches to be any different.
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Old 11-12-2016, 05:17 AM   #11
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While I use a hookah rig for the convenience of getting in and out of the water (no tank to take off), it also insures that I won't accidentally bang the tank against any part of my boat (including the prop) or my neighbors boat.

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Old 11-12-2016, 07:30 AM   #12
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Most shafts are bonded with or without brushes.

I disagree. Shafts are coupled to transmission gears embedded in oil. There is no reliable bonding bonding there. It does not require many ohms to prevent electron flow when the galvanic voltage differences between metals is only millivolts.
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Old 11-12-2016, 07:37 AM   #13
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Some suggest jumpers over both sides of the shaft coupling to ensure no or less resistance there too.
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Old 11-12-2016, 07:40 AM   #14
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How do you place jumpers onto a rotating shaft? I can think of only one exception and that requires a thrust bearing.
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Old 11-12-2016, 08:03 AM   #15
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Just copper straps from one side to the other.

I will try and find picture....

I also use a shaft brush and my transom zincs waste pretty well..but my shaft zinc looks new every year.
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Old 11-12-2016, 08:10 AM   #16
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How do you place jumpers onto a rotating shaft? I can think of only one exception and that requires a thrust bearing.
We added a jumper on ours. Using 2 ring lugs that fit the coupler bolts and ~3" of #10 wire. We jumper across the coupler on the same bolt. Our shaft is 2" diameter that spins at ~800-900 rpms. The shaft runs true and the alignment is good.
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Old 11-12-2016, 08:18 AM   #17
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Yep...couple ways to do it...on high speed shafts that brushes may be an issue, the copper straps can be measures and weighed to help balance more accuratelt...but probably overkill.
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Old 11-12-2016, 08:26 AM   #18
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What sort of damage? Other than convenience, I wouldn't have thought the two approaches to be any different.
As OC mentioned, it is very easy to imagine a diver with a bulky tank on his back banging up a boat's anti fouling paint or even gouging the gel coat.

From a personal standpoint, when I see a hull cleaner in the water or on the dock with a tank on his back (which is not often), I assume he doesn't know what he's doing. In any event, I do not allow my divers to operate that way.
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Old 11-12-2016, 08:46 AM   #19
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We added a jumper on ours. Using 2 ring lugs that fit the coupler bolts and ~3" of #10 wire. We jumper across the coupler on the same bolt. Our shaft is 2" diameter that spins at ~800-900 rpms. The shaft runs true and the alignment is good.
A picture might help. I cannot vision a jumper of any material connected to a rotating shaft. Of course, something could "rest" on top of such a shaft similar to what I call a shaft brush. My stuffing box is bonded but that doesn't by itself make an electrical contact to the shaft.

My first attempt to bond my rotating shafts used a bronze bar that rested on the shaft. It failed due to rapid wear. Today I use sintered oil impregnated bronze to make the shaft contact.
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Old 11-12-2016, 09:37 AM   #20
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Like this........ from Nigel Calder's book.....

For my brush, I use a discarded out drive zinc...already has a bolt for the bonding wire and arm attached. Got 3 seasons from the last and free from the marina pile is hard to beat.
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