Gori Props, "Durability.. cough cough"

[Trajan]

Gori Props, \"Durability.. cough cough\"

On our third at the moment, the Sail Drive props only seem to be lasting 2 seasons regardless of the location of the berth. We don't have electrolysis problems on the boat, our anodes last at least several seasons, the yanmar saildrive anodes last years! and the leg is in mint condition. Speak to gori they give it "oh you have problems, we'll offer you 25% off with your old prop returned" Well the first two cost £600/£700 the last one cost around £450, now there offering another one at that price but these props are not fit for purpose most other manufactures fit anodes to the insulted hub, gori dont bother, making there prop imho, unfit for purpose. I've gathered some evidence from members of our club, now i'm trying to find more cases. I'm thinking of taking it further with them. Unline companys such as Harken, who really will honour claims, even out of warranty (and even if you fit it wrong) their customer services seem to be slightly lacking...

Greg...


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[sailorman]

Re: Gori Props, \"Durability.. cough cough\"

i have a Maxprop of unknown age but i have owned the boat for 6 seasons, the prop is in good condition with on signs on de-zincification.
i have conventional stern gear on a "P" bracket & in marina berth.

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[sonic]

Re: Gori Props, \"Durability.. cough cough\"

I have a Gori 2 bladed folder fitted to my volvo saildrive since August 2003 and boat in the water all winter. Had it out for a couple of days in April for a clean and the anode fitted on the saildrive was 2/3rds gone. Local engineer who fitted prop removed prop and fitted new anode and when he replaced the prop on the boat he had polished it up so much we thought it was a new prop. On closer inspection confirmed it was our prop. So far I cannot find anything to complain about the prop nor the service from them or their agent.



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[extravert]

Re: Gori Props, "Durability.. cough cough"

My X99 had a Gori 2-blade folding prop. It lasted 14 years. It required replacing because of wear on the blades' interlocking teeth. There was no significant corrosion or dezincification at that age. I sold it second hand for repair.

All the early X99s have the same Gori prop. I have not heard of any problems with them, apart from teeth wear after about 15 years.

I am surprised your prop is corroding like you say. It is normally the aluminum alloy of the saildrive leg that is much more prone to corrosion than the prop, because aluminum is much less noble than bronze. Are you sure you don't have an electrical problem?

<hr width=100% size=1>One day, I want to be a real sailor. In the mean time I'll just keep tri-ing.

 

[Birdseye]

Re: Gori Props, "Durability.. cough cough"

If the saildrive anode is lasting years, it shows that it is doing very little work, maybe none at all. That could be the source of your problem.

Use a meter to measure the resistance between the anode and the leg itself (it should be very low) and if that is OK use the meter to measure the resistance between the prop and the leg.

I cant imagine that the prop is deliberately insulated from the drive gears and the leg itself. If it were, then it would need an anode. But if it is not insulated intentionally, then it might have become insulated by accident / corrosion from the leg anode that is probably intended to protect it. That is certainly what happens on the drive leg on my cat.

If the prop is intentionally insulated (why would they do that?) then maybe the Gori is not the right one for you. maybe you need a prop with a built in anode. But before you get really angry with gori, bear in mind that the huge majority of props do not have built in anodes because there is not reason / method of insulating them.





<hr width=100% size=1>this post is a personal opinion, and you should not base your actions on it.

 

[AndrewB]

Re: Gori Props, \"Durability.. cough cough\"

Yes, this was my reaction too. There is some fault in the configuration that is causing excess electrolysis on the prop. One way round this may be to use a different metal. Is a Gori made of brass or manganese bronze? It sounds as if a phosphor bronze or AB2 prop might be better.

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[Trajan]

Re: Gori Props, "Durability.. cough cough"

The data sheet we have for the prop reads as follows "the hub incorporates a flexible bush that absorbs shock and electrically insulates the propeller from the sail drive leg"

We have had a survey and I am an ocean chemistry expert, vie written several reports on electrolysis in brine... There is no "electrical leaks" from the yacht, our shore power is through isolating transformers, the Alloy Yanmar SD20 Sail drive leg is in perfect condition, no electrical (indicated by pitting or white deposits) or any other damage to the leg... With it being insulated I would have thought it would be critical for an anode to be fitted, hence my statement, the prop is not fit for purpose if it’s going to only last 2 seasons. Speaking to Volvo penta who manufactured their own line of sail drive props they state the anodes on the insulated prop hub are critical. For the record, its only sail drive props which are insulated, the shaft anodes on the conventional drive protect the props in that specific case hence they are lasting long. The sale of goods act states the item should be durable and fit for purpose, but you have to allow for quality, I am under the impression that Gori props are supposed to be one of the best you can buy?

The major problem is when the blades jam because of corrosion on the teeth and hub the vibration is massive! I'm told this could damage the leg or worse the seals, our dealer rekons we have a case. We also know it does not close properly and therefore will be slowing us down! We must get this sorted before cork week!! Not least the fact it may slow us down, but we need to sail 300 miles to get there!!

The berth location doesn't seem to affect the situation as we have had this happen in a few different locations, with or without shore power connected, there is at least one other yacht in our marina having similar trouble with their gori prop.

For those who tell me its from essesive use we have done less than 100 hours motoring!


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[malcp]

Re: Gori Props, \"Durability.. cough cough\"

I presume the gori prop is made up from dissimilar metals (Stainless steel for the gears, bronze for the rest?). If it were made from one type of metal (bronze) only then I would have thought insulating it and without an anode would be ok. But with more than 1 type I would have thought an anode is mandatory.

Is there not an engineering department at Gori you can talk to?

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[brianhumber]

Re: Gori Props, "Durability.. cough cough"

I must say I have been very impressed with my Gori, it has now been on for over 7 years and each winter refit returns to as new condition. However my anodes only last a season. You say yours last years so I would check through your anode connections and cross bonding. Once your anodes start to work as they should, I would suspect your prop will stop acting as your primary anode.
Also Marina berths can have very odd electrical leakage paths which play merry hell with metallic fittings.

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[Birdseye]

Re: Gori Props, \"Durability.. cough cough\"

Interesting. Are there disimilar metals in the construction of the prop that could be causing electrolysis. Or is it lubricated with something like graphite grease that could also cause problems? Or has the insulation been bridged but the anode is isolated?

Look at it another way. If Gori (and I have no connection with them ) were producing props in bulk that were unfit for purpose and required constant replacement, would they still be in business? Would we not have had it reported elsewhere? Would you not have had lots of people saying "me too " in response to your post? A bad batch can get out, but you have had several props over a period of time which suggests that they are all from the same batch, that all Gori folders are bad, or there is something peculiar in your installation.

Anyway, best of luck with your claim. If you ever find out for sure what the problem is, let us all know.

<hr width=100% size=1>this post is a personal opinion, and you should not base your actions on it.

 

[arvin555]

Re: Gori Props, \"Durability.. cough cough\"

The following are some quotes from Gori websites:

>>>>>>>>>>
The hub of the Sail-drive propeller is manufactured with a flexible bushing that absorbs shock and electrically insulates the propeller from the Sail-drive leg, as required by the engine manufacturers. The propeller fits most Sail-drives, for example: Bukh, Sonic, Volvo Penta incl. 50S-drive and 100S-drive, Yanmar and others.

The Gori propeller is cast from corrosion-resistant nickel-aluminum bronze. To avoid corrosion, the condition of zinc anode on the drive unit and the shaft should be checked prior to mounting and at regular intervals afterwards.
>>>>>>>>>>>>

Greg, I agree with the others who mentioned that it is suspect that your anodes last a long time, it might just be that there is something wrong in the system that is making your propeller act like it's the anode! My anodes in my old bukh (with Gori I guess coz extravert mentioned most X99 has Goris) lasts only about half a year or just a bit more.

Still with my move to a yanmar SD20 and a Gori propeller Greg's report will be keeping me on my toes, and will keep an eye on my anodes and propeller once I finish the project.

TTFN
Arvin