[Anonymous]

I have recently bought a 2002 year Bavaria 32 with a Volvo MD 2020 D sail drive and have just joined the BOA.

I noticed a sea water weep from the impeller housing, the brass plate that covers the impeller had suffered corrosion but at 10 years old I thought that was “normal”.

I have since fitted a new brass cover on the sea water pump and within 2 months it has suffered corrosion on the inner surface (not wear), the zinc has been leeched out of the brass to leave a soft copper. this brass cover plate has now stated to weep also.

I am also seeing what looks like a calcium deposit build up in the sea-cocks which if left unattended will eventually restrict the raw water intake.

I have been plugged into shore-power since January and do not have a galvanic isolator fitted (yet) but plan to fit one.

Has anyone else experienced this type of corrosion/erosion in the sea water pump and what was the remedy ?

Many thanks

[BobC]

Welcome to the BOA.

I’m afraid I can’t help you with this as I don’t know that engine, but I’m sure someone will be along soon with an answer.

I would suggest that you disconnect your shore power for the moment though, just in case that is your problem.

Cheers

Bob

[Anonymous]

Welcome!

It sounds an unusual problem. Have you had a chance to check the condition of the saildrive and more importantly the saildrive anode for degradation? It’s quite normal for the anode to gradually erode over time but usually it will require replacement at the end of each season. If the anode has completely eroded away then the next thing to go is the saildrive itself, which is definitely not a good thing! Also, it’s most important that the engine itself is electrically isolated from the gearbox and saildrive units; if for any reason the engine has been separated from the gearbox and replaced without the special isolating gasket and insulating washers for the securing bolts then it would be possible for electrolysis to start acting on the engine itself. Again, not good.

I too have a 2002 vintage 32 with the 2020 engine; even at 10 years old there shouldn’t be problems. My boat is left with shore power connected and on all the time and I’ve have had no problems like those you describe. I’ve often thought of fitting a galvanic isolator but while things remain as they are the boat seems perfectly OK without one. (She’s berthed in Chichester Marina, which I’m assuming has a reliable, correctly polarised shore power system!!)

I’m starting to get very hypothetical now, but does it look as if the corrosion is a recent thing or something that’s been happening longer term? If it’s recent then what’s changed to cause it? Also, I notice that you’re berthed in Ocean Village which has a lot of steel piling around its perimeter, this could theoretically be interacting with your boat. There are other BOA members in OV, might be worth chatting to them and also other boats near you to see if they have any problems.

Sorry I can’t be more helpful…

Ian Culley
B32 Another Fantasy

[Anonymous]

Ian,

Thank you for your help, I think I may have narrowed down the problem but I am still getting some conflicting information from some sources !

I can confirm that the saildrive isolation gasket is in place and in good order, as are the isolation spacers on the bolts.

The corrosion of the brass plate covering the impeller was eveident prior to me buying the boat in January but to a much slower degree. The previous owner rarely used shorepower long term (Brighton Marina) and also confirmed that anodes were replaced annually which was sufficient.

The anodes were in very good order in January this year when the boat was surveyed.

I can see that my hull anode is directly bonded the gearbox side of the engine isolation gasket (bonded twice, once at each end of the anode) which according to the Volvo agent is incorrect, the boat has obviously been like this for some time, maybe explaining the corrosion, now accelerated by both the use of shorepower and Ocean Village marina which can be harsh on anodes according to other berth holders.

However Clipper Marine say they often see this bonding arrangement between gearbox and and hull anode but all the install manuals from Volvo say this is incorrect !!

I have looked at another Volvo 2020 saildrive in the marina (in a Maxi 1000) and this too has the bond on the gearbox side of the isolation gasket to the hull anode.

I would be very keen to hear from other BOA members who have a 2020 Saildrive as to whether the hull anode is bonded to the engine block or gearbox side of the isolation gasket.

As I say the Volvo agent is very clear that the bond should be between the engine block and hull anode, but it would appear that in practice this is not always the case.

Many thanks

Simon
B32 – Rigmarole

[Anonymous]

I to have a B32 2003 with a marina shore supply. I have not suffered any of the symptoms you have experienced. My hull anode is wired as you describe. I changed the saildrive anode after 3 yrs although could have done another season. The hull anode has been on for at least 4 seasons.

[Anonymous]

Hi Simon, CaSam is down in OV and you are right about the amount of “stray” electricity!

(See previous post thread; viewtopic.php?f=3&t=792)

I no longer leave her plugged in and it has almost stopped the erosion.

I am not 100% of the bonding on my D120 but will be down the Marina over the weekend if you are down there…. feel free to give me a shout on berth B30

Steve

[Anonymous]

Simon
….one last thought. Have you checked that the water pump leakage isn’t coming from the seal on the engine side of the impeller drive shaft, these seals are prone to failure over time (mine was replaced about two years ago). I know that wouldn’t explain the corrosion you’re getting, but at least something else to check!!

Best regards

Ian
Another Fantasy

[Anonymous]

Hello Rigmarole, I sent you a PM with additional info. Down on the boat now and confirm hull anode bolts are wired together with two connections one to the sail drive and the other is bolted to the rear bell housing of the engine. I assume that the isolating engine fixings are the other side of the housing, although I have my doubts.

[Anonymous]

As a follow up can someone tell me how to identify the position of the isolating spacers?

[Anonymous]

Quick pic of the isolater on CaSam

[Anonymous]

….errrm the picture you’ve posted isn’t a galvanic isolator, it’s the charge splitter (diode) which divides the alternator output between service and engine start batteries.

A galvanic isolator would be connected in the earth circuit of the shore power supply, where it enters the boat.

Ian Culley
Another Fantasy

[Anonymous]

@another fantasy wrote:

….errrm the picture you’ve posted isn’t a galvanic isolator, it’s the charge splitter (diode) which divides the alternator output between service and engine start batteries.

A galvanic isolator would be connected in the earth circuit of the shore power supply, where it enters the boat.

Ian Culley
Another Fantasy

LOL oooops – sorry, well spotted Ian, wrong file uploaded!
😳

[Anonymous]

….easily done, got the t-shirt myself!!!!!

[Anonymous]

Not sure if you have problem licked. My leak bavaria32 age 2004) at water pump cover was as turned out the inner seal of pump as someone else experienced. Was that the problem in the end for you? Once replaced leak ceased. hope your already resolved. 8)

[Author]

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