I have been singing the praises of my Autoprop installed on my 37.5 for about one year. My boat was cleaned about 5 days ago and a Blade was missing! The next day, the diver (by braille) located it below the boat. Two of the blades are showing electrolysis on the tips, yet the hub and the blade that fell off are perfect. We can't figure out how this bladed fell off unless the ring the holds it in place in the hub where it goes into the hub into a grease fitting was defective. I haven't talk to Autoprop yet and am waiting until my diver gets his prop puller Monday and yanks it and puts my old prop back on. The good news is that it didn't come off and fly through my cockpit. The bad news is the money that I have spent on this prop that I will not have any confidence anymore. Has anyone ever heard of anything like this? ChuckWolfe@mail.com
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Electrolysis Comment cont.
John: I do not believe that having *your* boat connected or not to the electrical will make any difference. The problem is usually everybody else. This is a common problem is marinas in salt water. It would be interesting if the marinas would test for this.
John: I do not believe that having *your* boat connected or not to the electrical will make any difference. The problem is usually everybody else. This is a common problem is marinas in salt water. It would be interesting if the marinas would test for this.
Electrolysis and isolation, electrical problem
As others have pointed out, another yacht could well be causing your problem, as stray current passes due to the common earth ground. The solution is to fit a galvanic isolator, or isolation transformer at your 110 V shore side marina outlet. I don't know who sells these, but Feb 2000 issue of Practical Boat Owner, a fantastic UK publication, describes your problem and the solution. I would imagine most books on sail boat electrical would have a similar article. Jim O.
As others have pointed out, another yacht could well be causing your problem, as stray current passes due to the common earth ground. The solution is to fit a galvanic isolator, or isolation transformer at your 110 V shore side marina outlet. I don't know who sells these, but Feb 2000 issue of Practical Boat Owner, a fantastic UK publication, describes your problem and the solution. I would imagine most books on sail boat electrical would have a similar article. Jim O.
Corrosion
If your Autoprop problem was caused by corrosion, the the galvanic isolator or isolation transformer would be the ideal solution, if the corrosion is caused by other boats in the marina. The only way to be sure of that is to have someone check the boat with a corrosion test millivoltmeter. If the voltages read between the shaft and the reference anode (which is dropped into the water) vary much when the AC shore power cord is connected and disconnected, then the problem is probably another boat. You can temporarily alleviate this by simply disconnecting your shore power when you're not aboard. For another boat to cause a corrosion problem on your boat, the two boats must be electrically connected besides being in the same water electrolyte. The common ground (Green wire) on the shore power connection provides this electrical connection very effectively. Having said all that, your problem may not even be corrosion! Norm, H-40 "LIBERTY"
If your Autoprop problem was caused by corrosion, the the galvanic isolator or isolation transformer would be the ideal solution, if the corrosion is caused by other boats in the marina. The only way to be sure of that is to have someone check the boat with a corrosion test millivoltmeter. If the voltages read between the shaft and the reference anode (which is dropped into the water) vary much when the AC shore power cord is connected and disconnected, then the problem is probably another boat. You can temporarily alleviate this by simply disconnecting your shore power when you're not aboard. For another boat to cause a corrosion problem on your boat, the two boats must be electrically connected besides being in the same water electrolyte. The common ground (Green wire) on the shore power connection provides this electrical connection very effectively. Having said all that, your problem may not even be corrosion! Norm, H-40 "LIBERTY"
Hot Docks
Docks can be "hot" in terms of galvanic corrosion for a myriad of reasons. I'm four boats away from a 99' loa steel motoryacht built in the 1930's, and anytime there's that much metal in the water there's going to be a problem. In previous slips I've been close to fishing boats which were using car battery chargers to top off their house banks, which meant that zincs on the prop shaft would last no more than a month. You don't need a multimeter to tell how hot your dock is, just look at the condition of your zincs after a month goes by.
Docks can be "hot" in terms of galvanic corrosion for a myriad of reasons. I'm four boats away from a 99' loa steel motoryacht built in the 1930's, and anytime there's that much metal in the water there's going to be a problem. In previous slips I've been close to fishing boats which were using car battery chargers to top off their house banks, which meant that zincs on the prop shaft would last no more than a month. You don't need a multimeter to tell how hot your dock is, just look at the condition of your zincs after a month goes by.
Corrosion Problem
Charles, previous comments are pertinent, but only to a point. On my 430, I've had a serious electrolyis problem since day one. Installed a galvanic isolator, as I was told this would solve the problem. WRONG! By the way, the only UL-approved isolator is made my Mercury - you can get it from any Mercury marine dealer. However, at least my electrolysis problem is DC connected, not AC.I've had four "experts" spend hours trouble-shooting, but still haven't solved all the problem. Am going through zinc's (put an extra one one to prevent losing another prop) in about 5 months now, vs. 6 to 8 weeks before. Problem is stray DC voltage. Best source reference is Nigel Calder's book. He gives a great method to check for the source of your problems Good Luck! Pete KAILANI
Charles, previous comments are pertinent, but only to a point. On my 430, I've had a serious electrolyis problem since day one. Installed a galvanic isolator, as I was told this would solve the problem. WRONG! By the way, the only UL-approved isolator is made my Mercury - you can get it from any Mercury marine dealer. However, at least my electrolysis problem is DC connected, not AC.I've had four "experts" spend hours trouble-shooting, but still haven't solved all the problem. Am going through zinc's (put an extra one one to prevent losing another prop) in about 5 months now, vs. 6 to 8 weeks before. Problem is stray DC voltage. Best source reference is Nigel Calder's book. He gives a great method to check for the source of your problems Good Luck! Pete KAILANI
Me, too!
Charles, I too purchased anAutoprop and used it on my Hunter 410 for about 250 hours of engine use when a blade fell off as we were sailing one beautiful afternoon with the engine off. It was readily apparent by the shuddering of the entire boat. I anchore in the bay and dove to take a look, only to find two out of three blades. The hub where the third blade is attached showed no unusual wear or evidence of electrolysis, nor did any other part of the prop. Autoprop promptly overnighted me a new prop after I told them I didn't want to pull my prop and send it to them for repair as they initially suggested. The Autoprop representative told me this wa "most unusual" and offered no explanation of what happened. I've happily sailed and motored for about 130 hours of engine use since then without incident, but I do keep a puller and my old factory blade aboard. I don't see any evidence that my problem was electrolysis related. I'd love to know of any other similar problems. By the way, the Autoprop worked terrifically both for sailing and for motorsailing particularly. Fair winds! Chris Webb Grand Cru II
Charles, I too purchased anAutoprop and used it on my Hunter 410 for about 250 hours of engine use when a blade fell off as we were sailing one beautiful afternoon with the engine off. It was readily apparent by the shuddering of the entire boat. I anchore in the bay and dove to take a look, only to find two out of three blades. The hub where the third blade is attached showed no unusual wear or evidence of electrolysis, nor did any other part of the prop. Autoprop promptly overnighted me a new prop after I told them I didn't want to pull my prop and send it to them for repair as they initially suggested. The Autoprop representative told me this wa "most unusual" and offered no explanation of what happened. I've happily sailed and motored for about 130 hours of engine use since then without incident, but I do keep a puller and my old factory blade aboard. I don't see any evidence that my problem was electrolysis related. I'd love to know of any other similar problems. By the way, the Autoprop worked terrifically both for sailing and for motorsailing particularly. Fair winds! Chris Webb Grand Cru II
Install a Drivesaver
I keep my boat in a marina that has a lot of stray current. After several years of replaceing zincs on the average of one every two months(sometimes more frequently), I installed a drivesaver. Now the zincs last about six months. The prop is no longer the boat's anode.
I keep my boat in a marina that has a lot of stray current. After several years of replaceing zincs on the average of one every two months(sometimes more frequently), I installed a drivesaver. Now the zincs last about six months. The prop is no longer the boat's anode.
Hey Al,
...After doing several Net searches, I found lots of pages that talked ABOUT Drivesaver, but found only one phone number for a place that SELLS Drivesaver. The links to the Drivesaver site on sfsailing.com are no good. Can you point us to a site for the Drivesaver itself? I'd like to do some reading on it. thanks in advance.
...After doing several Net searches, I found lots of pages that talked ABOUT Drivesaver, but found only one phone number for a place that SELLS Drivesaver. The links to the Drivesaver site on sfsailing.com are no good. Can you point us to a site for the Drivesaver itself? I'd like to do some reading on it. thanks in advance.
Drivesever info
Try Defender's 2000 catalog page 185... small blurb there. I've had them on three boats with good success. There is a big difference between my props and my neighbor’s
Try Defender's 2000 catalog page 185... small blurb there. I've had them on three boats with good success. There is a big difference between my props and my neighbor’s
More drivesaver instalation request..
I think about installing the Drivesaver on my Hunter 95 '29.5 , equipped with Yanmar 2GM20F . From own experience -or others- does this unit dampen to some extend the vibration ? Since the shaft via engine was-and is- the 'ground' on many GRP standard boats, what did you do for ground instead? Installing this , one probably had to 'push' the shaft back a little ( the 1 inch thichness of the drivesaver added in fronf of shaft coupling disk )unless shortening shaft lenght. If so are there possible negative effects either noticed in practice or theorethical, on cutlass bearing wear ,or on any otherway ? Detailed information and opinion is highly appreciated. Alex. pascu@internet-zahav.net
I think about installing the Drivesaver on my Hunter 95 '29.5 , equipped with Yanmar 2GM20F . From own experience -or others- does this unit dampen to some extend the vibration ? Since the shaft via engine was-and is- the 'ground' on many GRP standard boats, what did you do for ground instead? Installing this , one probably had to 'push' the shaft back a little ( the 1 inch thichness of the drivesaver added in fronf of shaft coupling disk )unless shortening shaft lenght. If so are there possible negative effects either noticed in practice or theorethical, on cutlass bearing wear ,or on any otherway ? Detailed information and opinion is highly appreciated. Alex. pascu@internet-zahav.net
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