Is There an Alternative to the Yanmar SD50 ?

[Bigami]

Dear all,
in 2003 we aquired a brand new Lagoon410 S2, equipped with Yanmar 40HP & SD40. To sail the boat is a pleasure and we completed nearly 17.000NM in the Baltic Sea. The only, but constant disappointment are the saildrives. We began with the SD40, which have been replaced by SD50 because of oil leakage and early worn clutches and after sometime also the 2nd set of SD50 have been replaced because of early worn clutches. Now, Aug2010, after some 150h in service even the 2nd set of SD50s began again leaking oil and furthermore the portside SD shows significant change of oil color it turned already into black. A sign of abrasion, properly caused by the clutch. As you can imagine I am trying to get out of this circle of disappointments.
So, I am looking for an alternaive. Is there any one in the world who has found a recommendable solution, tex. fittings an other SD make onto the current Yanmar engine? ( the engine by the way works perfect).
I would be gratful for any constructive advise
with best regards
from SY Bigami

[sandy daugherty]

Please understand that I am responding only to the information that you have provided in this one posting, and I expect that there is a simple alternative to this observation. However;

Your experience is exceptional; There has not been a trend noted among similar installations. Your experience has continued after replacing all the suspect components. Since it is unlikely you could have replaced equipment with items having identical discrepancies, the next logical suspects would be outside the sail drives. That leaves a few mechanical aspects, and one big operational item: how you use the drives.
I have recently learned that I should not leave my SD-20's in reverse while sailing. Placing them in reverse for a moment is sufficient to stop the props from wind-milling, and water flow will keep them closed when I shift to neutral.
Having spent several years cruising on outboard engines, I have a habit of leaving the transmissions in neutral for a moment before going into forward or reverse.
Again, I'm responding to only your one message, based on my experience with a smaller Yanmar sail drive. My transmission oil still looks new after a hundred hours of continuous use.

[colemj]

The cone clutch problems on the SD20 and SD40 are well documented. The SD50 was supposed to be redesigned to prevent the problem (the SD40 was supposed to have been redesigned to prevent it also). Your problems do sound excessive. From where is the oil leaking? The shaft seals? Which props do you have on them?

I don't know if Volvo saildrives fit on Yanmar engines, but that might be an alternative for you. You may need an adapter plate to fit the mounting bolt patterns, but the big question is whether the shaft size and spline pattern will match. The Volvo SD's now use plate clutches instead of cones (actually a set of thrust washers).

Mark

[MacG]

There must be a reason for the excessive wear. Does this effect both diesels? Standard powering of the Lagoon 410 is only 27 hp per unit. Not particular extreme.
It is a given fact that a SD is less efficient and less rugged than the conventional shaft drive. A real alternative would be the installation of another brand - ZF SD-10 - which is overengineered and accepts up to 70 hp + engines.
It seems to me an engineering problem.

[DWT]

Originally Posted by Bigami

Dear all,
in 2003 we aquired a brand new Lagoon410 S2, equipped with Yanmar 40HP & SD40. To sail the boat is a pleasure and we completed nearly 17.000NM in the Baltic Sea. The only, but constant disappointment are the saildrives. We began with the SD40, which have been replaced by SD50 because of oil leakage and early worn clutches and after sometime also the 2nd set of SD50 have been replaced because of early worn clutches. Now, Aug2010, after some 150h in service even the 2nd set of SD50s began again leaking oil and furthermore the portside SD shows significant change of oil color it turned already into black. A sign of abrasion, properly caused by the clutch. As you can imagine I am trying to get out of this circle of disappointments.
So, I am looking for an alternaive. Is there any one in the world who has found a recommendable solution, tex. fittings an other SD make onto the current Yanmar engine? ( the engine by the way works perfect).
I would be gratful for any constructive advise
with best regards
from SY Bigami

Sorry to hear about all of your troubles with the sail drives. Being someone who would like to buy a catamaran with two of those things, sometimes makes me a little uneasy.
I have been trying to understand this whole “cone” clutch thing for awhile now and would better understand it, if I could see some photos of it or better yet, a parts manual. Other forums that have talked about it, I have piped in and ask for one or the other with no response.
Are the parts manuals guarded secrets? Any pictures of this assembly or know how of where someone could see, buy, steel , a parts manual would help a lot of us.

[Bigami]

Dear all,
thank you very much for all your fast and friendly responses. I think I will explore a bit more in depth the alternative with ZF Saildrives. If it works I will let you know.
Best regards from
SY Bigami

[MacG]

Shopmanuals are not to be found on the net. They have to be bought. And no, there are no secrets in this.

I suspect the boat is underpowered. She might weight far more than her designweight/displacement.
It depends on the way the weightcalculations are made and- important - the way the boat is manufactured. Exceeding the designweight by 20% is not unusual.
Two engines produce less efficient power than one single engine of same hp.

Most boatlifts have a weightindicator. Next time when the boat is hauled out, I should check the total gross weight.
There comes Sandy's remark around the corner - how do you run your boat under power. Do you stay within the range 0f 70% of rated power or do you go to the max?
Consider these points and you might find the answer.

[MacG]

Here are the principles of the working of a cone clutch. As you may see, not really suited for heavy-duty operation.
The Baltic Sea is a sea with heavy winds and requires powerful propulsion systems.
As I guess, it is an engineering problem, you use the boat outside her design-concept. Otherwise these problems wouldn't occur.
Talk with somebody of ZF-Friederichshafen, I am sure that they will advise you in this particular matter.

[DWT]

Originally Posted by MacG

Here are the principles of the working of a cone clutch. As you may see, not really suited for heavy-duty operation.
The Baltic Sea is a sea with heavy winds and requires powerful propulsion systems.
As I guess, it is an engineering problem, you use the boat outside her design-concept. Otherwise these problems wouldn't occur.
Talk with somebody of ZF-Friederichshafen, I am sure that they will advise you in this particular matter.

MacG,

Thanks for the thumb nail. A picture is better than a thousand words. So it is a spring loaded clutch, like a clutch plate in a car except it is a cone.
And am I correct in saying that it sits in an oil bath?

What part of this cone clutch most often fails in saildrives?

[MacG]

No David, it is a dry clutch system. The oil-spill must come or would come from the leaking joints of the internal gearboxgaskets.
Those Lagoons are not specifically designed for the Nordic waters and certainly not for Baltic conditions.
The available efficient horsepower is just sufficient for the propulsion of the designdisplacement under ideal conditions.

[DotDun]

Originally Posted by colemj

The cone clutch problems on the SD20 and SD40 are well documented.

FWIW, the SD20 and SD40/50 have different clutches. The SD40/50 has the 'cone clutch' that has caused problems for many in the past whereas the SD20 has a 'dog clutch'. I leave my SD20 saildrives in gear while sailing with 2 blade fixed props. No problems in 1500 hours and 7 years.

[alanglo]

I also have a Lagoon 410 S2 built in 2003.
We have exactly the engine / drive configuration that Bigami has.
The power of the Yanmar engines fitted is 40 HP/ side.( not 27) ( I have the manuals/specs in my file next to me)

We also have, as does nearly everyone else, propblems with the drive cones.
We do not have problems with discoloured oil.

The problem with the cones is limited to the SD40 and to a lesser extent the SD50 saildrive. I believe it to be an intrisic fault with the design or material of the cones. A system which can fail after only 180 hrs since maintenance and leave you without drive is not suitable for the task. I believe it to be incumbent on the manufacturer to market goods which are suitable for the task they are supposed to do. Dismantling the drive every 250 ( or 500 hrs in an SD50) is not really acceptable.

Our local Yanmar agent has suggested refitting with SD50s (£ ????) but they do not seem to be a solution.
If we do refit it will probably be with ZF drives( SD10?)which come well recommended, but again who is going to pay the bill?

Lagoon 410 is built to Cat 0, unlimited worldwide and many have done so not just the Med.I would have no qualms venturing into the Baltic on one and I am expecting to do a transatlantic next month on a new Lagoon 40.
Our boat is currently in Turkey.

I am currently in correspondence with Yanmar on this subject and will report the conclusion of that and the possible refit.
.

[Captain Bill]

Originally Posted by MacG

No David, it is a dry clutch system. The oil-spill must come or would come from the leaking joints of the internal gearboxgaskets.
Those Lagoons are not specifically designed for the Nordic waters and certainly not for Baltic conditions.
The available efficient horsepower is just sufficient for the propulsion of the designdisplacement under ideal conditions.

I have had my unit apart and the clutch definitely runs in oil. My guess is that Yanmar made a big mistake changing from a dog clutch to a cone clutch. Most small and moderately powered outboards use dog clutches. since the sail drives are basically limited to 70 HP a dog clutch should still work fine. Even if they wear at the same rate, at least they would be cheap and they basically take no maintenance. It's a wonder some smart machine shop owner hasn't made a retrofit kit. Since Yanmar won't warranty their clutches anyway, what's to be lost by putting in an aftermarket replacement?

[DWT]

Captain Bill,

If it is a dry clutch system and yours is coverewd in oil, is that the problem? Oil leaking on a (supposingly) dry clutch would cause slipping.

[SeaKing]

Our 470 has the heavy duty SD31 with dog clutchs, I have had "ZERO" problems with that in six years, my biggest issue is the oil changing. The fact that you have to haul the boat to change the oil. The new 50's you can change the oil from inside. The next problem is the O-ring seals, seems like they could improve that somehow.