SailDrive Anode

[CRYSTAL]

Hi Guys,

1) Would anyone know how the installation of the S130 leg anode is actually in contact with the drive leg? Is it by the bolts (threads) going through the leg mounting holes? If so, not much of a contact point. When the anode ring touches the drive leg, is the touching point supposed to be bare metal on the leg for good contact? Is there a way you can check using a normal multimeter performing a continuity check from anode to shaft?

2) How do you clean the anode under water if you see lots of growth. Or you just leave it alone.

3) Has anyone seen such holes on the back of their props?

thanks,
Hratch
S/Y Crystal

[Odysseus]

Electrolysis,  if you are in a marina, if not attention to your anodes,  clean and good contact through screws, but remember somtimes wear can take around the screws on the anode and make it loose.
Put safeshore marine into google and read.

Also put galvanic corrosion into this forum serch.
Odysseus

[CRYSTAL]

I thought so. So what's the solution if the screw
hole has enlarged and the threads are not making good contact w/ the leg?
Galvanic iso installed as well.

On another note would the galvanic iso protect the leg remembering that the leg is electricly isolated?

Thanks
Hratch

[njsail]

When I first purchased our Bavaria I took the prop off to change the anode.  To my surprise one of the bolts that was holding the anode on the head had corroded off and the other one snapped off when I tried taking it off.   Ever since then I take the prop off every year and check the bolts and anode.  I grease the kiwi prop and everything else right before we drop it back in the water.  That might be easier said then done for those of you lucky enough to be in all year long.  Right now it's 18 degrees out and I wish I was sitting on deck swinging at anchor in the Bahama's.    Anyway...I always keep a few extra anode bolts in the tool box just in case.   Thank you for posting and reminding folks....vigilance and diligence in maintenance is what keeps a boat in good shape.   Good luck.

[Odysseus]

There is a lot of info on this issue just need to search the forum.

I have bonded engine, saildrive, 12v, 240v,  back to stern via 6mm cable and anodes, zine for saltwater and magnesium for freshwater, one each side of stern on wire.

Odysseus

[Symphony]

There is a lot of info on this issue just need to search the forum.

I have bonded engine, saildrive, 12v, 240v,  back to stern via 6mm cable and anodes, zine for saltwater and magnesium for freshwater, one each side of stern on wire.

Odysseus

What are you hoping to achieve by doing that? The saildrive MUST be electrically isolated from the engine and should not be connected back to the engine. There is no need to connect the engine to any form of anode as it does not suffer from any galvanic action. Electrics should not be connected to an anode. The only possible reason for adding an anode is to increase the capacity of the saildrive anode and this can be done by bonding a hull anode or a hanging anode to the saildrive housing only.

[CRYSTAL]

I really have to agree with Symphony on this one Volvo is stating that the SD is Fully Electrically Isolated from the engine so nothing should NOT be used to earth (as per attached installation manual from Volvo - see attached on page 12 - very interesting.

Also, the whole leg if properly primed with Epoxy and connected with original Volvo zinc, this should protect it.

Hence my original query: how can we know if the Leg Anode is making a proper connection? Anyone know of any tests? And any proper cleaning methods under water due to lot of growth after 6 months or so? Who dares to answer this question

[Odysseus]

I belive Volvo are correct putting the statement in there warnings, aluminium is a less noble metal than iron, steel, or zinc so needs to be protected. However magnesium is a less noble metal than aluminium or zinc so should protect more.
As the saildrive is marinised,  protection is offered through this process, but what happens when that protection is compromised! As demonstrated in some of the forum comments, the zinc will win.

What does a spinning propeller have on its anodes?

I will stick with my 2 anode system but:-

Enough of this, each to his own.

Odysseus

[Symphony]

I belive Volvo are correct putting the statement in there warnings, aluminium is a less noble metal than iron, steel, or zinc so needs to be protected. However magnesium is a less noble metal than aluminium or zinc so should protect more.
As the saildrive is marinised,  protection is offered through this process, but what happens when that protection is compromised! As demonstrated in some of the forum comments, the zinc will win.

What does a spinning propeller have on its anodes?

I will stick with my 2 anode system but:-

Enough of this, each to his own.

Odysseus

But your second anode is not doing anything. It really is not necessary. If it was then the builder would have fitted one from new. The propeller is electrically isolated from the drive by a rubber bush in the centre. If it is aluminium it does not need an anode. However, if you have a folding or a feathering prop which has dissimilar metals in its construction - usually the pins and fastenings are stainless it will probably need anodes of its own. These can be in the form of rings, little buttons or zinc end caps depending on the design of the propeller. These are nothing to do with anodes on the boat or saildrive.

Perhaps you should read up on the causes of galvanic corrosion to understand why you do not need the second anode. Plenty of material on the web.

[Odysseus]

Thank you for your expertise.

Odysseus

[Symphony]

Thank you for your expertise.

Odysseus

My pleasure. Not saying anything that is not widely known and accepted. Just hope that nobody follows your example!

[CRYSTAL]

Massive thanks for the info.
would you mind testing something?
measure the resistance between the SD and the engine ensuring you have good contact
points,

Let me know the results.
Hopefully reading will be > 100K ohms which is basically no contact.

Also, can you send pics on where you connected the wire on the SD?

Did you paint the prop and cone? from your pics, seems that they are with original coatings.
Is it worth whiIe epoxy priming the leg for extra protection?

Thanks,
Hratch

[Symphony]

Common to coat the complete leg and prop with an appropriate antifouling such as International Trilux. I coated mine from new and get no fouling.

[Odysseus]

Kaptajnen, congratulations on a very informative artical.

Odysseus

[CRYSTAL]

Mystery solved.

BTW, looking forward in coming out to your area (when I retire and stil afoard a boat). I Lived in Vancouver for 18yrs and would be a dream to come back to sail the Gulf islands and fish for that tasty Coho or Chinook.

Regards

[Kaptajnen]

Crystal,

Hope you make it back here. We do most of our sailing in Puget Sound and around the San Juan islands - great cruising grounds 

BTW I added a photo to the above Picasa album showing the electrical survey after the boat was back in the marina with the new saildrive. As you can see, everything checked out - but I am having a diver do frequent checks for the next few months just to be on the safe side 
The cost of a new 130S saildrive is close to $8,000. plus another $5,000. for labor removing and installing!!! 

[nornie lees]

Hi All, i had my Bavaria 37 lifted by Sealift2 at Haslar Marina Portmouth, clean off hull, and anti-foul. Whilst in dock i went to change Anodes, the 3 piece Volvo folding prop anode was missing apart from the screws! The SD anode showed slight wear but considered to be good for another season.

When i bought the anodes from Golden Arrow(old marine tech) Port Solent they said Haslar marina yachts tend to suffer a lot more than other marinas in Portsmouth! Seems that way to me as i had replaced the missing anode in July this year and been on a singing mooring till end October, so  Oct---Nov the anode had wasted enough  around the 3 bolts to dissolve and fall off!

So on advise from the marina bar pundits i fitted a 30amp Galvonic Isolator, wired it as close to the incoming 240v supply through the earth wire on the inside of the yacht transom.

Now sit and wait, could i have done more?

Ray

[Stuart]

Hi All, i had my Bavaria 37 lifted by Sealift2 at Haslar Marina Portmouth, clean off hull, and anti-foul. Whilst in dock i went to change Anodes, the 3 piece Volvo folding prop anode was missing apart from the screws! The SD anode showed slight wear but considered to be good for another season.

Hi Ray One tip I was given was to paint the anode just around where the bolts are inserted  (We have a feathering Variprop) that area is very thin, so will tend to disappear very fast if not protected. It seems to work ,the anode breaks down as it should, the prop is in great shape and we don't lose the anode prematurely. I bought the paint and Zincs from the Zinc supplier in the States. They also sell at a great price the anodes for the sail drive.
BoatZinks.com

Cheers

Stuart

[Nigel]

We ended up replacing the damaged 120S with a new 130S saildrive - and here is where the Volvo information got even more contradictory and confusing, since all their literature emphasizes that the saildrive MUST be eletrically isolated from the engine... 

I have done exactly the same with the 130S leg. Not all saildrives are isolated, some rely on the entire engine being isolated, with relays that briefly connect it when stopping and starting.

See this thread.

[stevem]

Just been looking at this thread and noticed that I have the exact problem. When I lifted the boat out I noticed that the rotating blade on the Ambassador rope cutters was spinning and not rotating with the prop. The attached pics show my prop. The two holes are where the cheese head screws on the rope cutters recess into. the heads of both these fixing screws had sheered of and this is what I found when I removed the prop.
file:///C:/Users/Steve/Desktop/IMG_3427.JPG

[Symphony]

You can buy new screws, but as they hold the assembly together, worth getting the repair kit so that you can replace the bearings as well. Details on www.ropestripper.com

[ytd]

For reference our 44 sits on a swing mooring most of the year.  When it is pulled for annual antifoul the the 3 folding prop anodes are almost completely gone, some years to the point where there is just the screw left on one of them.  The SD anode is never more than half gone.  Some years it looks barely used but if you take it off and weigh it compared with a new one it is substantially lighter.

As long as the bolts that hold the SD anode are tight they will make good contact with the SD.  Even if the anode becomes loose as it erodes it will still make good contact with the bolts either directly or through the small amount of salt water between them.  Not sure how you would measure the resistance.  You would need to pass a long multimeter lead to a diver who could touch the anode with one end and the other lead going to the SD inside the boat.   

[dawntreader]

Our B37 was new in May 2006 and sat on a swinging mooring on the Exe for 2 years before moving to Brixham Marina. Although I have a new spare anode, I have never changed the original fitted SD anode (it is the only anode fitted to the boat).
I fitted a galvanic isolator on arrival at Brixham and always switch off the batteries/shore power when leaving the boat. There has been no pitting on the saildrive or prop - both are in pristine condition. I always remove and thoroughly clean the anode and screws each year. This includes weighing to ensure it is more than 50% of the weight of the new one. This was a recommendation by a Volvo engineer that I consulted at one of the boat shows. The the lack of deterioration (compared to what I read/hear) worried me but he assured me that nothing was wrong and the actions I have been taking have preserved the life of the SD anode.
Anyone else got my 'problem'?

[Nigel]

attached installation manual from Volvo ...

That looks interesting, where did you find it?

Later, found it here along with other manuals for the D1/D2

[CRYSTAL]

Hi Nigel,
It was from a diff site I think or someone emailed it to. I had posted it before as well under:
Companion way engine vents on B34.

Regards


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