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Post by davidlaw on Nov 24, 2014 22:26:30 GMT
Wow! Thanks Gentlemen, especially for switching over to a new thread (galvanic isolators) - I was beginning to feel guilty about what I'd started! I hope it doesn't come to blows (sorry!).
Anyway, much food for thought, and action. I will add a progress report sometime, plus the Jeanneau response, if and when I get one...
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Post by dbostrom on Nov 25, 2014 6:37:56 GMT
By a strange coincidence I'd just joined this forum* intending to ask a couple of questions about a survey report I've just had in for a SO39i we're on course to purchase. Lo, the first topic in "General" is this one, regarding p brackets, square on one of my targets.
Surveyor is a partner in a highly reputable firm. For what it's worth the report included this note regarding the vessel we're looking at:
For general background circumstances, the boat is equipped w/a galvanic isolator and being part of an active charter fleet is connected to shore power whenever it is not out, probably 25-30 weeks of the year.
Leaving aside whether it will actually do anything, I'm guessing there's no harm (other than a little more drag) in attaching an anode to the bracket?
*May I say how pleased and delighted I am to find JONF. What a fantastic resource; like the indispensable "Brickboard" for Volvo automobiles, except it's all about Jeanneau. Good reason to buy a production boat made in vast quantities; given models all break/degrade in the same way. Lurking here over the past few days has answered many questions-- thanks to everybody.
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Post by sitara on Nov 25, 2014 6:46:20 GMT
Hi dbostrom and welcome to the forum, it is a great resource and I am sure you will find many answers here. I cannot add anything new regarding cathodic protection, but the 39i is a great boat that I am sure you will enjoy.
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Post by dbostrom on Nov 25, 2014 7:16:08 GMT
Thank you, sitara. The first sailboat we ever chartered was a Jeanneau, for a week's go around the Whitsunday group in your neck of the woods. They seem to me decent designs, somewhat compromised by production cost savings but nothing really fatal in that way. They're ergonomic and friendly to crew in many ways. Funny thing is, only a very short while ago my nautical motto was "a pleasure boat is a boat I'm sailing but don't own" but this particular vessel's circumstances in combination with the dollar impact of our plans to do some longish missions circumvented my convictions. We plan on using this boat for coastal cruising in the Pacific Northwest; there are places in the region fairly distant where it can be better to have an option to hunker down and wait for weather to improve. Chartering can result in "must leave now" syndrome. Subscribing to Practical Sailor was the first step in my downfall. So much for resolve.
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Post by sailbleu on Nov 25, 2014 7:59:51 GMT
By a strange coincidence I'd just joined this forum* intending to ask a couple of questions about a survey report I've just had in for a SO39i we're on course to purchase. Lo, the first topic in "General" is this one, regarding p brackets, square on one of my targets. Surveyor is a partner in a highly reputable firm. For what it's worth the report included this note regarding the vessel we're looking at: [ quote]6. The bronze propeller shaft strut has beginning corrosion and has no cathodic protection.
Recommendation: Plan to drill this strut to allow bolting on a sacrificial anode to help preserve.
For general background circumstances, the boat is equipped w/a galvanic isolator and being part of an active charter fleet is connected to shore power whenever it is not out, probably 25-30 weeks of the year. Leaving aside whether it will actually do anything, I'm guessing there's no harm (other than a little more drag) in attaching an anode to the bracket? *May I say how pleased and delighted I am to find JONF. What a fantastic resource; like the indispensable "Brickboard" for Volvo automobiles, except it's all about Jeanneau. Good reason to buy a production boat made in vast quantities; given models all break/degrade in the same way. Lurking here over the past few days has answered many questions-- thanks to everybody.[/quote] ----------------------------------------------------------------------------- Look at that , a professional advise to install a zinc on the strut. First time i've read this , but as i mentioned earlier , this anode has scares therefor it must be doing something or helping out the strut. However Malcolm has a point warning us not to weaken the P-bracket too much. In my case it's two 6mm drilholes to keep the fairly large zinc to the bracket. And again it' s pitting very nicely , so it's there with/for a reason I would say.
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Post by artyman on Dec 7, 2014 23:05:09 GMT
Hi David,
Please see my post entitled Sunlight 30 engine earth braid Jan 11.
Does the earth braid from your engine going above your P bracket disappear into the fibre glass or does it have a visible metal to metal contact?
...........or is the braid just there as an earthing bar?
Kind regards
Bob
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Post by iancymru on Dec 7, 2014 23:49:58 GMT
Thanks for the description, it does help a lot. Was blind but now I see....
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Post by elecco on Mar 25, 2015 20:18:30 GMT
Wow....this has been a most helpful thread. I purchased my 2007 SO 39i a little over 6 months ago. I have the bottom cleaned and anodes checked by a diver every 6 weeks. The last two months the diver has had to change out all of my anodes. I started doing some research which of course includes this message board. We have some boats that are (IMHO) not properly cared for in our marina. I suspect they are "stealing" my protection. I'm going to check for AC leakage on all of my boats circuits to ensure the problem in not my boat (its possible, yes?). Regardless, I'm going to install a Galvanic Isolator. Any recommendations would be appreciated.
Regards,
Ed Lecco S/V PainKiller Alameda, CA
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Post by sleighride on Mar 26, 2015 0:10:32 GMT
I had minor signs of corrosion on the face of my Max Prop when the boat was hauled, but the prop zinc was still partially intact. However, I had an old shaft zinc still worn but attached and a new one with no wear. The Max Prop people at PYI said that there was stray current generated by the two shaft zincs interacting with the prop zinc and to remove one of them. I have followed this advice and have had no problems since. Lesson here is to not "over-zinc" a boat.
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Post by Mistroma on Apr 5, 2015 23:09:53 GMT
My 2009 42DS P bracket was also showing some initial signs of surface dezincification at the end of 2013 season. I'd spotted a slight "blush" at the start of 2013 and it was def. more defined at the end of the year.
I glassed in a fibreglass pad inside just off the centreline between the bracket and forward edge of the rudder. This was quite easy as there's plenty of space to work in the centre section on starboard side. The port side is full of hoses (exhaust, ducting etc.). I drilled through the hull and fitted a single MG Duff anode mounting stud with a pretty flat circular anode. The new anode is wired to the strap connected to the P-bracket.
It seems to have worked as the discoloured section has not grown in size and the anode has been eaten away slightly. I think that I may get 2-3 years from this anode which seems reasonable considering the size vs. the prop. anode and 2 shaft anodes.
I also fitted a galvanic isolator way back in 2010. I'd have preferred an isolation transformer but don't spend much time on shorepower, so decided the cheaper GI route would be adequate.
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Post by artyman on May 6, 2015 20:33:10 GMT
Hi David,
Please refer to my post (Jan 14) entitled "Sunlight 30 engine earth braid" in the general topics section.
My earth braid (engine to GRP above P Bracket)disintegrated but I couldn't see how to fit a replacement (still can't...)
At last (in you) I have found someone else with an earth braid appearing to go to the P Bracket. Can you see how the braid is connected please?
I don't appear to have any unexpected galvanic corrosion. Changing the prop shaft anode annually seems to be effective..
I'm one step off drilling down through the GRP to the top of the P Bracket to create a metal to metal electrical connection.
Thoughts?
Good luck with your issue.
Bob
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