Corrosion on Propellor
Printed From: myHanse.com
Category: Hints & Tips
Forum Name: 325
Forum Description: 352 Hints, Tips and News
URL: https://www.myhanse.com/forum_posts.asp?TID=6677
Printed Date: 27 March 2026 at 03:40
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Topic: Corrosion on Propellor
Posted By: Xantos
Subject: Corrosion on Propellor
Date Posted: 06 June 2012 at 14:34
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I just pulled my 325 out of the water after 7 months of use from brand new and was shocked to see the condition of the propellor, attached are the pics that I find unbelievable Has anybody seen corrosion to this extent ? What could be the reasons ?
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Replies:
Posted By: Xantos
Date Posted: 06 June 2012 at 14:51
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Sorry I had some problem uploading the pics here's a face book link with the pics https://www.facebook.com/photo.php?fbid=10150932053109294&set=p.10150932053109294&type=1&theater
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Posted By: JohnA
Date Posted: 06 June 2012 at 16:01
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Hi Xantos I have just seen your Facebook photo. The condition of your propeller is shocking, especially after such a short period, and something is quite clearly wrong. It looks quite beyond repair, certainly the blades are destroyed. From the looks of it the prop is a two blade Flexofold? There is no way in normal conditions that it should be in that condition. I have tried to look at your sail drive leg anode and, although it is not very clear in your photo, it does appear to be quite corroded although nothing like as bad as your prop. I suggest that there could be a bad earth bonding problem possibly causing the problem. May I suggest that you check the continuity of the bonding right through the hull, maybe by engaging a specialist engineer to help. It is also possible that where you berth could be causing part of the problem. Is there steel marina pontoon stanchions nearby, or indeed other steel structures which could be having a bad effect, including a poorly earthed steel hulled vessel? Normal shore power connection should not cause this sort of problem unless there is something else wrong. I had a two blade Flexofold prop fitted at the time of commissioning of my Hanse 320 and after one season it was still in immaculate condition with hardly any marking. You can see a photo of it in the 'For Sale' items section of MyHanse. It only needed a light wire brushing to get it to the state you see it in. Please don't think I'm trying to push it on to you, I only mention it so that you can see that a propellor of this type should still be in very good condition after a seasons service. I hope that you can get a solution to this soon. What is the condition of your other hull anode? Regards, John ------------- Hanse 320 #464 'Discovery' |
Posted By: Xantos
Date Posted: 06 June 2012 at 16:37
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Hi John Thanks for the reply. Yes its a 2 blade flexi fold Here are some more pics https://www.facebook.com/photo.php?fbid=10150932267539294&set=a.10150932266659294.438897.641654293&type=1&theater I spoke to the agent in India and was told there is no warranty on corrosion. The boats only been at a mooring never at a marina and never used shore power . No modifications to the electricals - everything is standard as it came from the factory The other hull anode is worn off completely !! Xantos  |
Posted By: JohnA
Date Posted: 06 June 2012 at 17:00
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Hi Xantos, This is really bad news for you. I would be very concerned if my Hanse agent made that comment to me and I would be requesting him to check the boat out very quickly. You say that the other hull anode has gone completely and this makes me really convinced that you have a serious earth bonding failure. May I suggest that you investigate your engine compartment to check that there is no evidence of corrosion to your engine, gearbox and/or sail drive components. Also check your batteries. Do you switch the battery master switches off when you are not on the boat? There should be no evidence of corrosion at the batteries on a boat of that age if nothing else is wrong. If your distributor (agent) won't give immediate help to you, you really do need to engage a marine electrical expert immediately before other damage is done. I would also kick up an awful fuss with Hanse if your agent (who I assume sold the boat to you) will not help you! I suspect that something may have gone wrong at the commissioning stage. I suggest that, as the sail drive anode is not badly corroded that it is the prop which is taking all the corrosion in that area, this may suggest that the problem may be the bonding of the sail drive? Good luck with solving this problem. I have looked at your yacht on your Facebook pages and she looks really beautiful. It is a real regret that many Hanse owners throughout the world seem to have complaints about their distributors. In the UK we are lucky to have a good one who takes their responsibilities seriously and will always help with advice no matter how long after the original sale. Regards, John ------------- Hanse 320 #464 'Discovery' |
Posted By: JohnA
Date Posted: 06 June 2012 at 17:44
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Hi again Xantos, Sorry, I forgot to say that I was unable to see the additional photos mentioned in your link. Could you please check the link? Regards, John ------------- Hanse 320 #464 'Discovery' |
Posted By: Brufan
Date Posted: 06 June 2012 at 17:57
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Normaly with a 325 you have a Volvo engine (D1-20 or D1-30). Volvo saildrives are electrically isolated from the engine and so from the yacht electrical systems. If you look carefully to the bolts between saildrie and engine you will see that they're kept in a plastic housing and there's a ring of isolation between engine and gearbox. So with a Volvo engine there shouldn't any electric flow between them. If there is, there's something wrong. If you switch the mains electric off (both service and engine) check with an Ohmmeter if there's any flow between them. This could be one of the failure that can explain. You can also check about faulty electric flow in the marina. In my harbour, yachts located close to the professionnal fishing part (where's ships use shore power and genset) see their anode worn within 6 mounths. Although yachts located 100 meter away don't have problems with thier anode. ------------- Bruno hanse 355 - 57 S/Y Spicy Ginger White hull, 2 cabins, Volvo D1-30, Selden rig, removable mainsheet track system, Simrad (now B&G)-Jefa autopilot. |
Posted By: Xantos
Date Posted: 06 June 2012 at 18:58
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Hi John Here's the link again https://www.facebook.com/photo.php?fbid=10150932267539294&set=a.10150932266659294.438897.641654293&type=1&ref=nf Xantos
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JohnA wrote:Posted By: Andrew
Date Posted: 12 June 2012 at 09:21
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Hi Xantos I had a similar problem last year, see my previous post with a picture of the hole in my prop. This is definitely an electrical problem. Your prop, being alloy is acting as your saildrive anode, and be happy that the saildrive did not go down the same road as your prop, because it is also alloy and would cost many thousands to fix. Several things to consider. Firstly you must use a non copper content antifouling on your prop. For example Trilux33. Secondly, as previously mentioned, the saildrive must be electrically separated from the engine, if the control cables make contact with both engine and saildrive then you must insulate them some how. Thirdly is the saidrive anode making good contact to the saildrve housing. Fourthly if a steal boat is within 20 metres you will act as his anode. Fifthly if the marina has a poor set up with there electrical supply you need to decouple your boat from the marina supply. Since I use a 50 watt solar panel, and do not need the use of the marina power, where a steal boat is moored 20 meters from mine, I have less electrolysis Hope this helps Andrew |
Posted By: Xantos
Date Posted: 12 June 2012 at 11:49
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Thanks for the reply , Im still scratching my head trying to figure out the cause of the corrosion. None of the well known causes seem to be the reason.
Xantos
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Posted By: André
Date Posted: 12 June 2012 at 20:50
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Your Flexofold propeller is made out of bronze, which is a relatively noble and seawater and corrosion resistant material. However, the saildrive version of this propeller (and most other brands of fixed and folding propellers) are electrically isolated from the saildrive shaft by means of a vulcanized rubber bushing construction in the propeller hub. This rubber construction is meant as isolator and to reduce the forces on the saildrive during engaging the clutch forward/reverse. Gori has e.g. exchangeable zinc anodes mounted on the propeller hub, I cannot recall how this was with Flexofold, when I remember correctly it has none. Looking at the pictures I suspect indeed galvanic corrosion, but then there must be a source close or connected to the propeller of material more noble then the propeller. The reason that your saildrive anode is still intact and your saildrive leg too indicates to my opinion the propeller is electrically isolated from the propeller as these would sacrifice itself for the more noble propeller. Also don't underestimate the influence of more hot seawater, which is more corrosive then colder seawater. The reason that your hull anode (connected to keel, rudder stock, ground, engine block etc.) has been gone in a relatively short time period (mine is hardly attacked after two seasons) indicates that the area where your boat is moored seems to need proper cathodic protection. Am afraid your prop needs this too, but strange why your saildrive anode is still in relative good condition compared to the one on the hull. And: what props do other boats around have? Is your boat moored in water with a tide current, so flow around the hull? (Galvanic) corrosion can be a complex issue, you need to know the source as a new prop may otherwise end up the same.
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Posted By: skipper
Date Posted: 12 June 2012 at 21:45
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I am so sorry when reading this serious problem.
It sounds very strange that you have got those damages without being connected to shore power, an isolated propeller should not get those damages.
When seaking for information how to solve this in short and long term you could get in contact with the manufactor of the propeller. My experience is that the Danish Flex-O-Fold company has helped myself and friends so if you ask them about guidelines they might have some ideas about the possible root cause in your harbour. http://www.flexofold.com/contact/" rel="nofollow - http://www.flexofold.com/contact/ ------------- Cheers, Skipper Former owner of Hanse 342 2005 (Sparcraft mast, white hull, wheel steering, deep draft keel, short rudder) |
Posted By: Xantos
Date Posted: 13 June 2012 at 06:33
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Thanks for the reply. Looking at the damage that is limited to ONLY the prop I tend to agree with your theory that possibly the prop is completely isolated exposing it to corrosion. You are correct - The Flexoflod does not have exchangeable anodes like the Gori. My earlier posts did indicate that the hull anode was completely gone because I didn't see one when I inspected the boat , I now understand that the 325's do not have an additional hull anode-atleast hull #079 had no hull anode. There is a Ground cable connected to the Keel and one to the rudder stock. Hanse has subsequently sent a Technical Dealer Bulletin (TDB) dated 24th Feb 2012 advising that the rudder stock ground connection to be disconnected. I completely clueless as of now what to do.  Nandan
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Posted By: Brufan
Date Posted: 13 June 2012 at 09:55
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[QUOTE=Xantos] There is a Ground cable connected to the Keel and one to the rudder stock. Hanse has subsequently sent a Technical Dealer Bulletin (TDB) dated 24th Feb 2012 advising that the rudder stock ground connection to be disconnected. My yacht was recall by the dealer for wrong heater installation. When they fixed it they also remove the ground cable from rudder shaft according to yard's instruction. ------------- Bruno hanse 355 - 57 S/Y Spicy Ginger White hull, 2 cabins, Volvo D1-30, Selden rig, removable mainsheet track system, Simrad (now B&G)-Jefa autopilot. |
Posted By: 341 Agathe
Date Posted: 13 June 2012 at 19:58
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It's a bit of a mystery why the Hanse yacht has installed ground cable on the rudder shaft keel and sail drive. According to the experts, it will result in korrrosion which also occurs. On this link http://www.myhanse.com/forum_posts.asp?TID=6193&title=rudder-stock-corrosion" rel="nofollow - http://www.myhanse.com/forum_posts.asp?TID=6193&title=rudder-stock-corrosion there has been a lively debate concerning same topic. Corrosion attack the vital parts, and generates high Repairing expenses. ------------- Agathe 341 2003, white hull, tiller steering, deep draft keel, long rudder |
Posted By: 341 Agathe
Date Posted: 13 June 2012 at 20:00
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It's a bit of a mystery why the Hanse yacht has installed ground cable on the rudder shaft keel and sail drive. According to the experts, it will result in korrrosion which also occurs. On this link http://www.myhanse.com/forum_posts.asp?TID=6193&title=rudder-stock-corrosion" rel="nofollow - http://www.myhanse.com/forum_posts.asp?TID=6193&title=rudder-stock-corrosion there has been a lively debate concerning same topic. Corrosion attack the vital parts, and generates high Repairing expenses. ------------- Agathe 341 2003, white hull, tiller steering, deep draft keel, long rudder |
Posted By: André
Date Posted: 13 June 2012 at 21:05
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Xantos, I think it would indeed be a good idea asSkipper describes to ask advise from Flexofold on your issue. Such an amount of corrosion is abnormal, there must be an explanation. What also is typical is the corrosion looks worst on the blade tips. The price of a flexofold is high enough to let them assist you. You could at least give it a try. I have 320 and it has an additional hull anode connected to ground, keel, rudderstock and probably also engine block. If the 325 doesn't have this, I would indeed consider to disconnect the aluminium rudderstock and leave it on its own, as it otherwise may sacrifice itself against the cast iron keel (is more noble) and can therefore understand why also Hanse in the meantime recommends this.
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