Mainship 350 prop cavitation vs clutch?

Hi

I have just completed a sea trial of a 1997 Mainship 350 (single Yanmar 315 HP). When at WOT there was either an occasional slipping of the clutch or a prop cavitation. Has anyone had experience with either of these. The mechanic that was along for the sea trial was not sure which it might have been. We are waiting on oil sample analysis of the transmission.

Thanks
Burk

Burk
I guess from the lack of response to your post, this has never happened to anyone. I have a 2003 390 with a 370 Yanmar and it has never happened. I generally run at 1950 rpm with a run up to 2500-2800 every couple of hours for 10 minutes or so. The boat has only seen wot 3 times in the 5 years i've had her. If you don't have prop damage, I can't imagine cavitation. I'm interested in hearing what your oil sample comes back with.
John

I am having a problem with prop cavitation as well. It is the factory prop and I can find no history of such a thing on the 350/390. I should have the oil back in the next 48.

Burk

Burk Thacker said:

I am having a problem with prop cavitation as well. It is the factory prop and I can find no history of such a thing on the 350/390. I should have the oil back in the next 48.

Burk

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If you really want to know join the Mainship group on Yahoo and then ask the question. I can think of at least three folks that will chime right in.

mainship : This list is for Mainship Owners and others who want to own a Mainship.

Just got the oil samples back. It is the tranny. She's making metal. I am in the process of figuring out the cost of fixing it.

Burk

Burk

What if the "cavitation" persists after the tranny is fixed?

sunchaser said:

Burk

What if the "cavitation" persists after the tranny is fixed?

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My guess it won't. So far no one has jumped on this as he has posted it on the Mainship site. So if that had been a problem in the past it is a lot like here, you can't ask a question without three different replies and sometime for the same person.

JD, herein lies the boat buying frenzy problem. The anxious buyer WANTS the boat so badly that he is willing to take a chance that a bad tranny will fix an issue that could be at least 3 different things and ends up with a lemon. An honest seller would fix the tranny "problem" and then go to seatrial again, if not buyer beware. Especially given Luhrs on again off again financial issues.

Hi Burk
making metal is not good. Hopefully it's a bearing coming apart. If its a gear and it is through the hardness it will quickly damage the other gears. The clutch plates would also have to be shot, as a bad bearing or gear would not cause the transmission to slip. Not sure whose marine gear is in your boat. Mine has a ZF Hurth but I think Yanmar also makes a marine gear. If you're going ahead with this, also have the transmission cooler removed and cleaned.
I think this repair would probably cost about $2K (maybe a little more) not including labor to remove and re-install.
Good luck
Johnma
MS 390

Burk Thacker, Sunchaser is right. When I first saw my current boat the starboard transmission was out being repaired. I refused sea trial or survey until it was fixed and reinstalled, despite the broker`s urging. Then we did a sea trial (without surveyor) and the starboard engine overheated. I refused to survey the boat until that was fixed, despite the broker suggesting my surveyor diagnose the problem, with price adjusted. The owner fixed both issues before I arranged general and mechanical survey.
It is just possible the owner is selling because he can`t fix the cavitation issue. How can your surveyor give the boat a full hard run with that problem? Get the owner to fix it first unless you are totally sure what it is, the price gives you full allowance and a good margin for error and is otherwise good.

Getting the owner to fix the problem is best I agree. To encourage them to do it you can make a somewhat low-ball offer on as as is basis, arguing that you have to budget for thorough repairs. Of course by forcing the owner to repair you would be wise to also have some control over the quality of the repair by vetting/approving the repairer. A repair that is just a cheap and nasty quick fix is the worst possible outcome.

sunchaser said:

JD, herein lies the boat buying frenzy problem. The anxious buyer WANTS the boat so badly that he is willing to take a chance that a bad tranny will fix an issue that could be at least 3 different things and ends up with a lemon. An honest seller would fix the tranny "problem" and then go to seatrial again, if not buyer beware. Especially given Luhrs on again off again financial issues.

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I agree. There is no way I would do that deal without the transmission up an running and no cavitation problems.

BTW there is no Luhrs off and on anymore. They are gone completely. Marlow Marine has bought the Hunter, Mainship and one of the other brands out of the Bankruptcy Court. They have the Hunter division up and doing business and it has never missed a beat. The hull molds for Mainship were hauled down to FL a couple of months ago and the word is that Marlow Mainship will be up and running soon. It is a perfect fit for a company that builds upper end 50' and 70 footers. I don't remember what they are doing with the other brand.

As far as Mainship goes I think it is a good thing. Marlow - Mainship (the new company) has taken over the web site and are advertising that they will get parts for present owners. Also with Marlow running the totally new company I can see no down side. They will add a certain amount of class to the name plate and some will rub off on the older boats, maybe.

Hi

Thanks for the input. My assessment of the transmission is there is more than one thing wrong with it. The combination of slipping at WOT and the levels of iron and copper points in a couple of directions. At this point I don't see moving ahead with the purchase until such time as the transmission is fixed. Considering what is possibly wrong with it I am looking for a new tranny as part of the deal. The boat was sold as "in immaculate condition" and a metal making, slipping unit comes well short of that.

Thanks
Burk

Oh Ya. I forgot to mention it is a Borg Warner Velvet Drive (I think 71C or 72C still looking into that). Any comments on this transmission?


Burk

A repair that is just a cheap and nasty quick fix is the worst possible outcome.[/QUOTE]

Right on. Saw dust in the transmission just will not get it.

sd

Burk,
Velvet Drives are pretty good transmissions. They are widely used in heavy construction equipment (mostly backhoes). I'll check with our shop tomorrow and see what the issues are in repairing these and what you should see for hours between failures. Seems to me that that is a pretty new boat for a transmission failure. He might have gounded hard and bent the shaft and kept running with a bent shaft causing a bearing failure then a seal leak causing low pressure then slipping clutches. Failures tend to snowball after a small problem is left to get worse.
Johnma
MS390

Burk
I checked with our shop manager this morning. the largest failure for Velvet Drives in marine applications is the forward clutch pack. he said it fails from being run at a continious high rpm. The pump also wears causing low clutch pressure. He feels the metal in your oil sample is from the pump. (this is also the primary cause for most manufacturers)
We repair a lot of Velvet Drives, and while we are not a distributer for them (they are owned by Regal-Beloit), we are an authorized service and warranty center for Dana-Spicer-Clark-Hurth as well as Allison and many hydraulic manufacturers (Eaton-Vickers; Muncie; Permco) so our guys know what they're talking about. Not sure what part of the world you're in (we're east coast, US), you can email me privately at jmalley@transaxle.com with your contact info and I can hook you up with one of out techs
John
MS390