Hi, I recently hauled our 2011 Hanse 355 after 12 month in the water. The anodes were new 12 months earlier and as she came out of the water it was obvious we had a serious problem. The sail drive had catastrophic corrosion and a hole in the leg you could put your hand through.
The cause is not clear, the shaft anode was largely intact and not significantly eroded. The prop was unaffected, I have heard that in the last 12 months as many as 30 boats here in aussie have suffered similar fate and I would love to connect with other Volvo sail drive owners who have had challenges like this..
Select to expand quoteSailingGuy said..
Hi, I recently hauled our 2011 Hanse 355 after 12 month in the water. The anodes were new 12 months earlier and as she came out of the water it was obvious we had a serious problem. The sail drive had catastrophic corrosion and a hole in the leg you could put your hand through.
The cause is not clear, the shaft anode was largely intact and not significantly eroded. The prop was unaffected, I have heard that in the last 12 months as many as 30 boats here in aussie have suffered similar fate and I would love to connect with other Volvo sail drive owners who have had challenges like this..
HI SG,
I hadn't heard anything, I had the boat on the hard in January and there was not a hint of corrosion (2015 DI-30) .
Is it in salt water? In a marina or private mooring? Kinda reeks of a short, sounds like a lot of current flowing to earth.
Edit: was the saildrive anode eaten away ? And the prop anode unaffected?
Select to expand quoteSailingGuy said..
Hi, I recently hauled our 2011 Hanse 355 after 12 month in the water. The anodes were new 12 months earlier and as she came out of the water it was obvious we had a serious problem. The sail drive had catastrophic corrosion and a hole in the leg you could put your hand through.
The cause is not clear, the shaft anode was largely intact and not significantly eroded. The prop was unaffected, I have heard that in the last 12 months as many as 30 boats here in aussie have suffered similar fate and I would love to connect with other Volvo sail drive owners who have had challenges like this..
I have seen this a few times before and if I recall correctly it stems from having a poor fitting or an incorrectly fitted anode not making good contact with the leg.
I can't remember if it was a fault with the fitting dimensions of the anode or just inexperience in making sure it is correctly fitted. Either way, the anode was not doing its job and the leg was dissolving whilst the anode was unaffected.
Interesting trivial sidebar to this stuff....in submarine cables 12VDC is used to power the undersea amplifiers. When the cable is split into a T-Piece, a trunk cable with a spur cable tapping off it, you run two DC circuits. One for the trunk (powered both ends from the land stations isolated from the sea) and one for the spur (powered from one end, the cable station on the spur and earthed to the sea through the amplifier )
If you powered up the station connecting the spur cable with a + polarity and used a - polarity as the sea earth, the corrosiveness would eat about a 1kg of metal out of the amplifier casing over a few weeks. If you powered it as a - polarity at the station and used a + sea earth, the equipment has a rated life span of 20+ years.
An amplifier can be laid down to a depth of 8000m, imagine having to replace anodes on that sucker 
.
Select to expand quoteJolene said..SailingGuy said..
Hi, I recently hauled our 2011 Hanse 355 after 12 month in the water. The anodes were new 12 months earlier and as she came out of the water it was obvious we had a serious problem. The sail drive had catastrophic corrosion and a hole in the leg you could put your hand through.
The cause is not clear, the shaft anode was largely intact and not significantly eroded. The prop was unaffected, I have heard that in the last 12 months as many as 30 boats here in aussie have suffered similar fate and I would love to connect with other Volvo sail drive owners who have had challenges like this..
I have seen this a few times before and if I recall correctly it stems from having a poor fitting or an incorrectly fitted anode not making good contact with the leg.
I can't remember if it was a fault with the fitting dimensions of the anode or just inexperience in making sure it is correctly fitted. Either way, the anode was not doing its job and the leg was dissolving whilst the anode was unaffected.
This is what Joelene is referring to. In seawater two dissimilar metals that are electrically connected will act as a battery, where current will flow between the two.
This means that one metal will be losing material, or metal ions, to the seawater. Which one loses material is determined by the metals anodic index. To stop the damage to the expensive bits, you introduce a third sacrificial metal, the anode.
If you are protecting brass with zinc, there is a voltage difference of approx 1.4V. The zinc has the lowest anodic index, it will lose material, not the brass.
If you protect aluminium with zinc, there is a voltage difference of approx 0.3V. The zinc is the lowest anodic index, it will lose material, not the aluminium.
If you tried to protect brass with gold for example, this won't work, the brass will lose material and not the gold.
So, as Joelene said, if you do not have a good electrical contact between the zinc and the aluminium saildrive, the zinc is not losing material, something else will. The bigger the voltage difference, the quicker the material will be lost. This is why your prop (bronze) anode will decay faster than your saildrive (alloy) anode.
If the cause is not external to the boat (a dodgy neighbour in a marina) then the aluminium in your saildrive is unfortunately the metal with the lowest anodic index in the circuit and is losing material....ergo it's going to be toast.
Example Case Study: You don't have any anodes on your saildrive or prop and neither have any waterproof coating. The bronze and aluminium are electrically connected and immersed in seawater. Which metal is going to corrode first?
Edit: Whilst I am using the prop and the leg as an example, my Volvo saildrive had electrical isolation between the prop and the leg, (hence the two anodes), I am not sure if this is the same for all Volvo legs. Metals need to be connected electrically to cause galvanic corrosion, so use a multimeter to check for high resistance (good) if you are not sure.
Select to expand quoteSailingGuy said..
Hi, I recently hauled our 2011 Hanse 355 after 12 month in the water. The anodes were new 12 months earlier and as she came out of the water it was obvious we had a serious problem. The sail drive had catastrophic corrosion and a hole in the leg you could put your hand through.
The cause is not clear, the shaft anode was largely intact and not significantly eroded. The prop was unaffected, I have heard that in the last 12 months as many as 30 boats here in aussie have suffered similar fate and I would love to connect with other Volvo sail drive owners who have had challenges like this..
I operate a Corrosion Engineering company and one of the leading sacrificial anode manufacturers in Australia. Out of a personal interest ( protection of my Yanmar SD40 Saildrive) I have developed a "Saildrive" protection kit. Please PM for details if interested.
Select to expand quoteshaggybaxter said..SailingGuy said..
Hi, I recently hauled our 2011 Hanse 355 after 12 month in the water. The anodes were new 12 months earlier and as she came out of the water it was obvious we had a serious problem. The sail drive had catastrophic corrosion and a hole in the leg you could put your hand through.
The cause is not clear, the shaft anode was largely intact and not significantly eroded. The prop was unaffected, I have heard that in the last 12 months as many as 30 boats here in aussie have suffered similar fate and I would love to connect with other Volvo sail drive owners who have had challenges like this..
HI SG,
I hadn't heard anything, I had the boat on the hard in January and there was not a hint of corrosion (2015 DI-30) .
Is it in salt water? In a marina or private mooring? Kinda reeks of a short, sounds like a lot of current flowing to earth.
Edit: was the saildrive anode eaten away ? And the prop anode unaffected?
Thanks, sail drive anode only minimal reduction for 12 months in the water, there is no anodes on my prop so just the volvo split anode on the shaft.
Select to expand quoteJolene said..SailingGuy said..
Hi, I recently hauled our 2011 Hanse 355 after 12 month in the water. The anodes were new 12 months earlier and as she came out of the water it was obvious we had a serious problem. The sail drive had catastrophic corrosion and a hole in the leg you could put your hand through.
The cause is not clear, the shaft anode was largely intact and not significantly eroded. The prop was unaffected, I have heard that in the last 12 months as many as 30 boats here in aussie have suffered similar fate and I would love to connect with other Volvo sail drive owners who have had challenges like this..
I have seen this a few times before and if I recall correctly it stems from having a poor fitting or an incorrectly fitted anode not making good contact with the leg.
I can't remember if it was a fault with the fitting dimensions of the anode or just inexperience in making sure it is correctly fitted. Either way, the anode was not doing its job and the leg was dissolving whilst the anode was unaffected.
Thanks, this was the suggestion that there may have been some issues with the volvo anode around this period. I fitted the anode myself and usual light rub to clean up of the shaft and secured firmly.
Select to expand quoteshaggybaxter said..Jolene said..SailingGuy said..
Hi, I recently hauled our 2011 Hanse 355 after 12 month in the water. The anodes were new 12 months earlier and as she came out of the water it was obvious we had a serious problem. The sail drive had catastrophic corrosion and a hole in the leg you could put your hand through.
The cause is not clear, the shaft anode was largely intact and not significantly eroded. The prop was unaffected, I have heard that in the last 12 months as many as 30 boats here in aussie have suffered similar fate and I would love to connect with other Volvo sail drive owners who have had challenges like this..
I have seen this a few times before and if I recall correctly it stems from having a poor fitting or an incorrectly fitted anode not making good contact with the leg.
I can't remember if it was a fault with the fitting dimensions of the anode or just inexperience in making sure it is correctly fitted. Either way, the anode was not doing its job and the leg was dissolving whilst the anode was unaffected.
This is what Joelene is referring to. In seawater two dissimilar metals that are electrically connected will act as a battery, where current will flow between the two.
This means that one metal will be losing material, or metal ions, to the seawater. Which one loses material is determined by the metals anodic index. To stop the damage to the expensive bits, you introduce a third sacrificial metal, the anode.
If you are protecting brass with zinc, there is a voltage difference of approx 1.4V. The zinc has the lowest anodic index, it will lose material, not the brass.
If you protect aluminium with zinc, there is a voltage difference of approx 0.3V. The zinc is the lowest anodic index, it will lose material, not the aluminium.
If you tried to protect brass with gold for example, this won't work, the brass will lose material and not the gold.
So, as Joelene said, if you do not have a good electrical contact between the zinc and the aluminium saildrive, the zinc is not losing material, something else will. The bigger the voltage difference, the quicker the material will be lost. This is why your prop (bronze) anode will decay faster than your saildrive (alloy) anode.
If the cause is not external to the boat (a dodgy neighbour in a marina) then the aluminium in your saildrive is unfortunately the metal with the lowest anodic index in the circuit and is losing material....ergo it's going to be toast.
Example Case Study: You don't have any anodes on your saildrive or prop and neither have any waterproof coating. The bronze and aluminium are electrically connected and immersed in seawater. Which metal is going to corrode first?
Edit: Whilst I am using the prop and the leg as an example, my Volvo saildrive had electrical isolation between the prop and the leg, (hence the two anodes), I am not sure if this is the same for all Volvo legs. Metals need to be connected electrically to cause galvanic corrosion, so use a multimeter to check for high resistance (good) if you are not sure.
Really interesting, I just purchased a silver reference anode so I can keep a close eye on the bond system voltage and this table makes lots so sense so much appreciated.
Select to expand quoteSailingGuy said..shaggybaxter said..Jolene said..SailingGuy said..
Hi, I recently hauled our 2011 Hanse 355 after 12 month in the water. The anodes were new 12 months earlier and as she came out of the water it was obvious we had a serious problem. The sail drive had catastrophic corrosion and a hole in the leg you could put your hand through.
The cause is not clear, the shaft anode was largely intact and not significantly eroded. The prop was unaffected, I have heard that in the last 12 months as many as 30 boats here in aussie have suffered similar fate and I would love to connect with other Volvo sail drive owners who have had challenges like this..
I have seen this a few times before and if I recall correctly it stems from having a poor fitting or an incorrectly fitted anode not making good contact with the leg.
I can't remember if it was a fault with the fitting dimensions of the anode or just inexperience in making sure it is correctly fitted. Either way, the anode was not doing its job and the leg was dissolving whilst the anode was unaffected.
This is what Joelene is referring to. In seawater two dissimilar metals that are electrically connected will act as a battery, where current will flow between the two.
This means that one metal will be losing material, or metal ions, to the seawater. Which one loses material is determined by the metals anodic index. To stop the damage to the expensive bits, you introduce a third sacrificial metal, the anode.
If you are protecting brass with zinc, there is a voltage difference of approx 1.4V. The zinc has the lowest anodic index, it will lose material, not the brass.
If you protect aluminium with zinc, there is a voltage difference of approx 0.3V. The zinc is the lowest anodic index, it will lose material, not the aluminium.
If you tried to protect brass with gold for example, this won't work, the brass will lose material and not the gold.
So, as Joelene said, if you do not have a good electrical contact between the zinc and the aluminium saildrive, the zinc is not losing material, something else will. The bigger the voltage difference, the quicker the material will be lost. This is why your prop (bronze) anode will decay faster than your saildrive (alloy) anode.
If the cause is not external to the boat (a dodgy neighbour in a marina) then the aluminium in your saildrive is unfortunately the metal with the lowest anodic index in the circuit and is losing material....ergo it's going to be toast.
Example Case Study: You don't have any anodes on your saildrive or prop and neither have any waterproof coating. The bronze and aluminium are electrically connected and immersed in seawater. Which metal is going to corrode first?
Edit: Whilst I am using the prop and the leg as an example, my Volvo saildrive had electrical isolation between the prop and the leg, (hence the two anodes), I am not sure if this is the same for all Volvo legs. Metals need to be connected electrically to cause galvanic corrosion, so use a multimeter to check for high resistance (good) if you are not sure.
Really interesting, I just purchased a silver reference anode so I can keep a close eye on the bond system voltage and this table makes lots so sense so much appreciated.
Sorry, I shoulda said 0.9V for bronze to zinc, not 1.4V, Sunday morning pre-coffee .
Select to expand quoteRamona said..
What antifouling paint was on the saildrive?
It doesn't actually make any difference which antifouling paint is used on aluminium. The Saildrive and Antifouling manufacturers will claim of course that it does and no doubt any warranty issues with corrosion on the leg likely be denied if normal antifouling paint was used. However the antifouling paint makes no difference to corrosion of Aluminium. My own studies, conducted on a number of Saildrive legs that had previously been lost to corrosion suspended and monitored over several months AND studies published in corrosion journals by others confirm this. For the past 5 or 6 seasons I have used the same Antifouling paint over the entire boat including the Saildrive leg and Aluminium rudder bearing housing. I do however have the bearing housing and Saildrive leg electrical bonded and place a suspended Anode wired to the internals of Saildrive leg. This is to extend the life of the leg Anode ( which can or should be replaced underwater in any event). I now find that I comfortable get a season from my antifouling whereas previously the Aluminium antifouling on the leg, rudder housing and surrounding are fouled much more rapidly than the rest of the boat. One season I experimented with a cuprous oxide boosted mix ( to USA concentrations) and comfortably got 2 years out of the antifouling. However, I now insist on an annual slipping anyway so don't turbocharge.
Whatever you say on saildrive legs but I certainly would not use copper rich antifoul on an aluminium hull.
That is the one big drawback with aluminium yachts. Very regular antifouling with fairly ineffective paint.
Select to expand quotefrant said..Ramona said..
What antifouling paint was on the saildrive?
It doesn't actually make any difference which antifouling paint is used on aluminium. The Saildrive and Antifouling manufacturers will claim of course that it does and no doubt any warranty issues with corrosion on the leg likely be denied if normal antifouling paint was used. However the antifouling paint makes no difference to corrosion of Aluminium. My own studies, conducted on a number of Saildrive legs that had previously been lost to corrosion suspended and monitored over several months AND studies published in corrosion journals by others confirm this. For the past 5 or 6 seasons I have used the same Antifouling paint over the entire boat including the Saildrive leg and Aluminium rudder bearing housing. I do however have the bearing housing and Saildrive leg electrical bonded and place a suspended Anode wired to the internals of Saildrive leg. This is to extend the life of the leg Anode ( which can or should be replaced underwater in any event). I now find that I comfortable get a season from my antifouling whereas previously the Aluminium antifouling on the leg, rudder housing and surrounding are fouled much more rapidly than the rest of the boat. One season I experimented with a cuprous oxide boosted mix ( to USA concentrations) and comfortably got 2 years out of the antifouling. However, I now insist on an annual slipping anyway so don't turbocharge.
All the yachts on the local slips with sail drives always paint the sail drives in non copper based paint. Years ago I had an aluminium fishing vessel with a Volvo sterndrive and I religiously used non copper based antifoul paint. I was replacing the Volvo anodes every 3 months or so. For a week or so I had a Steber 34 longliner tied up alongside at the wharf. He had copper based antifoul and when he left I found 2 bob marks all the way down one side at the waterline. The marks were about the size of a 2 bob coin and about 1mm deep. After one week! Next time on the slips I stripped the whole bottom.
