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Post by simonthepom on Jan 2, 2015 23:35:12 GMT
Some further collective wisdom required... in in the pre-purchase survey we had done, the surveyor says "The 3-bladed bronze propeller was hammer tested and found to be showing some early signs of de-zincification." he didn't make any further mention of it in the recommendations at the end of the report, but just wondering what everyone's view on this is? Obviously the consequences of losing a blade or the whole prop disintegrating is just nasty. what should I do? thanks,  Attachment Deleted |
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Post by Don Reaves on Jan 3, 2015 0:42:57 GMT
I'd start by requesting further information from the surveyor, including probable causes of the problem, how to fix them, and whether it is safe to continue using the prop.
There are threads on the forum concerning corrosion that you will find useful. Look for "galvanic" using the search page.
Another recommendation that comes to mind is to replace the prop, not just because it might be damaged, but also for better sailing performance. There are threads on folding and feathering props that may be helpful.
But I think the first thing to do is find and eliminate the cause of the problem. I'd look for sources of stray current, either on your boat or nearby boats.
Don
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Post by alex1949 on Jan 3, 2015 8:20:57 GMT
Hi Simon. surveyor is talking about past galvanic damages caused by external currents . This can damage your prop because it is made from relatively "soft" metal that will be damaged first. Signs of damage to prop can be seen clear enough, small holes and metal eating/melting all around. A total fail of prop in this case is very rare but it certainly weaken the prop and make it less smooth. Reason for that usually points toward unprotected galvanic activity. You might have a zinc installed but may be there was no sufficient connection to the shaft/prop nose or at past times somebody did not replaced zinc in time while still in working order. My advise will be : install a galvanic isolator assap,it is relatively cheap and simple to install this will extend dramatically your zinc life,very important for boats far away from you. You do have to continue use zinc and install them carefully. I will do nothing regarding the prop, one day you will change it to a folding/feathering . Alex |
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Post by electricmonk on Jan 3, 2015 10:26:34 GMT
I would fit a galvanic isolator and a folding prop, you will be at peace and sailing a knot faster.
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Post by On y va on Jan 3, 2015 11:07:31 GMT
Looking at the photo, the zincs look ok to me and are doing their job.
I think the surveyor is referring to some pitting, which can be seen on the prop as well as on the p-bracket. It does make me laugh he found this after hammer testing....... He must be a very special man.
The props fitted by Jeanneau are ok, but not of the best quality around. They (and Beneteau) all seem to have this issue.
So, as suggested by others: install a galvanic isolator (you can buy them plug and play from Safeshore without having to find and cut wires) and start saving for a feathering or folding prop. Then just keep the orginal wrapped up in bubble wrap as spare somewhere deep down in the bilges.
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Post by Don Reaves on Jan 3, 2015 12:45:36 GMT
... as suggested by others: install a galvanic isolator (you can buy them plug and play from Safeshore without having to find and cut wires) ... A galvanic isolator needs to be installed in series with the ground earth wire just before your shore power inlet. Safeshore's instructions indicate you do need to cut the ground wire to install the isolator. Safeshore Install Guide
Don |
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Post by sailbleu on Jan 3, 2015 13:04:03 GMT
I would fit a galvanic isolator and a foldin g prop, you will be at peace and sailing a knot faster. Expecting mine next week electric , a 50 amp with led indicating , as the Aussie legislation requires . A folding prop however is not on my NTB-list (need to buy). Regards |
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Post by On y va on Jan 3, 2015 16:37:12 GMT
... as suggested by others: install a galvanic isolator (you can buy them plug and play from Safeshore without having to find and cut wires) ... A galvanic isolator needs to be installed in series with the ground earth wire just before your shore power inlet. Safeshore's instructions indicate you do need to cut the ground wire to install the isolator. Don No Don, You do not need to cut anything. Plugging in two europlugs is all you need to do. www.safeshoremarine.com/Inline%20isolator.htm |
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Post by Don Reaves on Jan 3, 2015 21:47:28 GMT
You're right! I was looking at the instructions for a unit that was installed in the boat, not inline with the cord.
Don
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Post by simonthepom on Jan 5, 2015 10:03:56 GMT
thanks for the replies all.
The galvanic isolator sounds like a no brainer given it's only 100 GBP. I've just discovered the new thread about these devices, so will go and read that now.
Re the folding prop, I have previously enquired about a Flexofold prop from Denmark - they rated quite well in a test I read a while ago. Anyway, no matter the brand, a folding prop also seems like a no brainer, except for the cost. I was quote about 1800 Euro delivered.
I took your advice Don and contacted the surveyor. He said the prop was likely to be original, so going on 20 years old now... But he said the prop should be OK for the next couple of seasons, and to hammer test when we haul out. Apparently ringing is good, dull dead sound - not so good...
So I'm still in two minds about the folding prop, peace of mind first and foremost, but also potentially another knot and given we're planning to cross the Atlantic at the end of the year, that might make a bit of difference. A fast passage is a safe passage don't they say?
cheers,
Simon
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Post by hoppy on Jan 5, 2015 11:04:09 GMT
thanks for the replies all. The galvanic isolator sounds like a no brainer given it's only 100 GBP. I've just discovered the new thread about these devices, so will go and read that now. Re the folding prop, I have previously enquired about a Flexofold prop from Denmark - they rated quite well in a test I read a while ago. Anyway, no matter the brand, a folding prop also seems like a no brainer, except for the cost. I was quote about 1800 Euro delivered. I took your advice Don and contacted the surveyor. He said the prop was likely to be original, so going on 20 years old now... But he said the prop should be OK for the next couple of seasons, and to hammer test when we haul out. Apparently ringing is good, dull dead sound - not so good... So I'm still in two minds about the folding prop, peace of mind first and foremost, but also potentially another knot and given we're planning to cross the Atlantic at the end of the year, that might make a bit of difference. A fast passage is a safe passage don't they say? cheers, Simon I fitted a flex-o-fold before I even sailed Jessabbé. The thought of having something onboard that slowed me down that added no other value to the experience (compared to the folding) was too much for me  |
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