Volvo dph sterndrives prop corrosion

[CliffPoulter]

I would like to make contact with users of Volvo sterndrives (DPH model) that are experiencing corrosion issues with their propellors to understand whether this is a common problem. When once the engines (2 x Volvo D6-310s in my case) are out of warranty, it appears that Volvo are reluctant to accept responsibility.

 

[CHI]

DPH sterndrive propeller corrosion

HI
I have twin D4 260hp engines which are 2005 vintage. I am on the original set of props but had to have them refurbeb last winter. The problem was pitting in areas of the blades and along the hub where the blade connects.Not sure wether problem was from corrosion or cavatation caused by the duo prop effect? Hamble propellers did a great job.
Three years ago i had the VP active corrosion system fitted. This has certainly helped with anode wear rate . I can now launch in feb?mar and all anodes only 40% worn when lifting nov?dec same year. Wear rate much quicker before. I do not think the system will protect props as i am lead to beleive that the rubber hub bushing isolates.

How bad is your problem. Do you have any pics?

Regards

Keith

 

[volvopaul]

Volvo have replaced many props under warranty, but not after the 2nd year, thats classed as wear and tear! yes what a joke I know.

I have seen many sets badly corroded and its down to the area or marina your berthed in a lot of the time, the material IMHO was not as it should be, I would say they should have made them from stainless steel in the first place, one set I looked at in Salterns marina were nearly scrap, after a big fight the dealer dealt with it and new ones were supplied foc.

 

[GrahamHR]

I wouldn't be too sure that stainless props would have solved it; my original stainless DPS props started to corrode. the replacement ones showed the start of corrosion in the same place after 6 months immersion; on the inside of the hub, in the narrow gap close to the plastic bush.

What looked like a small rust spots turned out to have large holes filled with a black sludge behind them, once the remaining thin "skins" of stainless were removed.

As a previous poster indicated, the anodes/ active corrosion protection unit do not protect the props (the inner aluminium bush, yes, but not the hubs/ blades). Interestingly I have seen no corrosion on the blades at all, which makes me think it's crevice corrosion, maybe originating between the bush and hub.

 

[Geoffs]

I started a thread about this a while back. here

There is a photo there. My boat is dry berthed, so don't believe it's corrosion, I felt more likely to be cavitation. Whatever, this Nibral material seems rubbish, I wish someone would produce G series stainless props.

If I had to replace mine after 600hrs use, that would be £2 per hour just for props!!!!

 

[Greg2]

I think location is a big issue. I have been through sets of props in a season due to corrosion but there is an issue in my marina. I have also heard the theory about the rubber bush isolating the prop from the anodes but having put a tester on there is connectivity so I am not convinced by this theory. We did find that a lot of grease on the shaft affected connectivity so something to consider.

 

[CliffPoulter]

I am in contact with two other boat owners who have this issue. They have boats like mine that are 2-3 years old, have had one set of props replaced under warranty, now have signs of corrosion on the second set, but find Volvo unresponsive to approaches that this should be treated as a full warranty claim because the items are not fit for the purpose. All have the VP active anti-corrosion system fitted and have changed the sacrificial anodes on a regular basis.
With the manufacturer ignoring attempts at contact, it seems owners may draw some strength if this proves to be a common problem. Perhaps if there are enough customers coming forward, then they will take the matter seriously.
I have enquired about stainless steel props, but have been told Volvo do not offer them for DPH legs, not sure why. I see in the USA they have a composite sterndrive and props, but they are not offered in Europe.
CHI mentioned having his repaired by Hamble Propellors. It would be interesting to know what they do when dealing with corroded props. Do they treat them in some way, fill up the holes caused by the pitting, etc etc. Is this a long term resolution to the problem, or just a short term fix?
At some point it may be appropriate to re-approach Volvo Penta when the issues will be:
a) What is a reasonable life expectancy for these propellors assuming they have not been damaged, 1,2,3,4,5,10 years?
b) If they corrode within whatever the reasonable period is, should Volvo extend their warranty to cover lifting, labour and replacements?
c) Are Volvo doing anything to resolve this issue with new engines being supplied currently? Are they changing the metallic composition of the props?
d) Is there an alternative propellor supplier that can offer a metallic combination that does not suffer from corrosion in this way?

 

[[2068]]

The composite drive will not cope with anywhere near the torque produced by the higher output versions of the D4, let alone a D6. In any case, it has been discontinued and replaced by an aluminium drive with a special coating.

Interestingly, I have seen a couple of boats locally with DPH drives and "painted" props.
I'd be very interested to know:
1.) What the paint or coating is
2.) Does it work?

 

[nicho]

I know a mate with a Doral, fitted with D4's, has had his props changed virtually every year under warranty, but only after a lengthy argument. This last time Volvo refused to help, and I know it was a hefty old bill.

 

[[2068]]

What I don't get is that I have supposedly disposable Alu props, and 3 out of the four date from 2003. A bit tired, but still serviceable.

Nibral is used to make lots of other props successfully - why do they fizz away attached to a DP-H?

dv.

 

[CliffPoulter]

Painting had been suggested. Having done a bit of googling, I found a couple of articles that suggested it was a bad idea to paint the props as it reduces efficiency / performance.

 

[novanta]

Props from a 2004 Portofino 35 with D6-310's. This year the boat was moored near a old steel lock, and I think that is the problem here. The drives were OK, no signs of corrosion at all.

I always paint them with Prop-O-Drev antifouling.

 

[Greg2]

CHI mentioned having his repaired by Hamble Propellors. It would be interesting to know what they do when dealing with corroded props. Do they treat them in some way, fill up the holes caused by the pitting, etc etc. Is this a long term resolution to the problem, or just a short term fix?

They can't do much with corroded props unless it is very minor. When they corrode the properties of the metal change and the prop has effectively had it.

 

[CHI]

DPH Sterndrive Prop Corrosion

Hi Again
After my props were refurbed by Hamble propellers, they were returned in a shiny bronze condition. I wished to try and protect them as well as possible so decided to overcoat with a two part system called "Propspeed". This is a fairly costly option but worth a go cosidering the cost of new replacement Nibral props from VP.
During the season i kept an eye on growth on props as this was an issue in the past. Propspeed certainly kept the barnacles and weed at bay. On lifting i coverd the props with towels to protect from the power washer. The coating should last for a couple of years. All that was needed was a wipe over with a damp cloth to bring back to a coated shiny bronze finish. Only a couple of ares of wear. However i have noticed a few areas of signs of corrosion , but nowhere as bad as previous seasons.
Has anyone else used Propspeed ?

 

[GrahamHR]

I think location is a big issue. I have been through sets of props in a season due to corrosion but there is an issue in my marina. I have also heard the theory about the rubber bush isolating the prop from the anodes but having put a tester on there is connectivity so I am not convinced by this theory. We did find that a lot of grease on the shaft affected connectivity so something to consider.

As far as the DPS "F" series stainless props are concerned, it's not a theory, but a fact. I have just checked all six I have in the garage; one pair from 1999, one pair from 2004 and one pair from 2008. There is no electrical continuity whatsoever between the stainless hub/ blades and the inner hub on any of them.

On the VP website, prop guide, they indicate that the DPH G series props have "complete electric isolation". Do the (stainless) GR series suffer from corrosion as well? Are they an option ? (the size range is more limited than for the G series).

 

[CliffPoulter]

I tried emailing Hamble Propellors to find out more about the repair process, cost etc. No reply to date, so guess they are not interested.

 

[Geoffs]

I took my props to Hamble, who looked at 'em, um'd and ah'd, intake of breath through teeth etc., and told told me to carry on using 'em. Fair enough I suppose, but just felt a lack of real interest.

Took them to Propeller Solutions just outside Poole, who said blades were bent. They repaired them (nicks etc) straightened, re pitched, tidied and polished, £90 for the pair. Still got cavitation/corrosion pitting, but they should do another season, at least.

 

[jimmy_the_builder]

I've got DPH drives with nibral props, which had suffered minor pitting when I bought the boat. They were refurbed by Hamble Propellors in April this year.

My surveyor did a bit of research into this corrosion issue - and his conclusion was that it isn't galvanic corrosion, it's cavitation corrosion and is related to the power output of the drive vs the relatively small size of the prop. It is certainly the case that another T40 that we looked at last year had got through about three sets of props because of the pitting - and that particular owner liked to go everywhere flat out (= lots of cavitation).

I'm just waiting for some US manufacturer to start producing stainless aftermarket props, the drives have been around a few years, it can't be long now, surely?

Cheers
Jimmy

 

[Geoffs]

I concluded cavitation, although I don't go everywhere flat out, 2500rpm, 25 knots is the norm. Agree with you, someone please produce some stainless G series props.

Did Hamble fill in all the pitting? They seemed reluctant to do this when I discussed

 

[jimmy_the_builder]

To be honest I don't know the detail - Fairline Southampton organised this as part of our purchase agreement, I didn't deal with Hamble Propellors directly. The props came back looking like new though:

Right. I'm off down the boat. Happy Christmas!

Cheers
Jimmy