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Old 28-01-2015, 00:49   #1
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I am so confused – too much information here

… or is it just noise?

I know not a thing about Yanmar SD-50 sail-drives and have no experience with them so any information you can offer is appreciated. I have read a lot of Yanmar documents and hundreds of internet messages and long threads about Yanmar sail-drives.

The information I receive from seemingly credible voices is contradictory and confusing.

The catamaran we are trying to buy has a pair of 2005 Yanmar 4JH3-TE (75HP) engines which each power a Yanmar sail-drive. The engines have about 2400 hours on them.

In July 2014 the current owners replaced the original SD50s with new Yanmar sail-drives. I am trying to determine if they put in SD50s or SD60s. The owner is out of the country and I need to get permission to board the boat again to look at the drive units. I have not gotten a straight answer about the reason for the sail-drive replacements.

I talked to the owner of a large boat brokerage. He says they have sold hundreds of sailboats, many of them new, with SD50 sail-drives and have had only one warranty issue. That problem was caused by the failure of the boat owner to keep zincs on the sail-drive.

I read hundreds of postings on the internet about all the problems owners have had with their SD50s but then the boat dealer tells me they have never had a problem.

I see posts on the web where sail-drive owners claim that when the SD50 is properly maintained they are reliable and then I see some owners claim they have had the same problem with three consecutive SD50 units.

I also see that French boat builders are now putting only sail-drives in almost all their monohulls, catamarans, and many of their fast trawlers which seems to be a real vote of confidence.

Now, I find an August 2013 Press Release from Yanmar that seems to say they are replacing all SD40/SD50 units with a totally redesigned SD60 including a dog clutch and better oil seals. That seems to be a real vote of NO-Confidence.

Are the Yanmar SD50 sail-drives a potential problem or are they a stable and useful drive unit when well maintained?

A second question is about oil changes in the Yanmar sail-drives:

I see that Yanmar makes a pressure system to force oil out or a suction system to pull it out. The local dealer tells me that neither works well and they recommend that the oil only be changed when the boat is out of the water and the lower drain plug can be pulled and gravity lets all the oil drain out.

That sounds like an expensive option in a 51’ catamaran with a 28’ beam, which costs $600 to $1,000 to pickup here in San Diego. Changing the oil every 250 hours or once a calendar year at a cost of $1,000 means the sail-drive costs at least $2/hour to operate (a pair of engines) or twice the sum of all other operating costs.

Is it really necessary to haul the boat out of the water (or put the boat on the beach on it’s keels) to change the SD50 sail-drive oil?

I do understand that I can change the oil when I paint the bottom every third year but I am concerned about the times we are off cruising and put a lot of miles on the boat.

A third question is about motor sailing:

The Yanmar Sail-Drive operation manual says:
NOTICE: When sailing, set the remote
control lever in neutral. Not doing so WILL
introduce slippage and void your warranty.

NOTICE: Running for long periods at low
rpm with the Sail-Drive engaged can cause
slipping and premature wear of the cone
clutch.


Those two statements seem to prohibit motor sailing. I have read a number of internet messages that describe the problems caused by motor sailing when the wind or wave action is strong enough to cause the boat to surge ahead of the thrust provided by the sail-drive.

When we are passage making in our 40’ cutter we motorsail a lot when we cannot maintain a 3-knot sailing speed. We frequently are able to make 6 or 7 knots motorsailing with an engine speed 500 RPM lower than with no sail.

Is it possible to motorsail with SD50 sail-drives and not damage or cause excess wear on the clutch and drive shaft?
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Old 28-01-2015, 05:29   #2
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Re: I am so confused – too much information here

Quote:
Originally Posted by TacomaSailor View Post
… or is it just noise?



Are the Yanmar SD50 sail-drives a potential problem or are they a stable and useful drive unit when well maintained?

Yes, of three owners with sd50s I know they all had problems with slipping and sometimes not engaging gear at crucial times, such as entering marinas. Personally I would avoid having them. When we ordered our last cat the option was 30hp with sd 20 or 40hp with sd 60. I prefer the 40 but would have gone with the 30 if they were still using the sd 50 with the 49hp.
The owners with sd 50s spent a LOT of time finding mechanics, spending time in marinas for services and chasing up warranty claims with yanmar and lagoon. Not something I enjoy doing...
I would contact an authorised yanmar mechanic to discuss their experience to confirm your doubts.

A second question is about oil changes in the Yanmar sail-drives:

Is it really necessary to haul the boat out of the water (or put the boat on the beach on it’s keels) to change the SD50 sail-drive oil?

I think the sd20 requires this method which isn't very effective as it sucks the oil from above the gears. The sd 50 and 60 has a lower oil drain plug which allows for on water oil changes. We have had ours changed on the water twice and it was fairly simple.


A third question is about motor sailing:

The Yanmar Sail-Drive operation manual says:
NOTICE: When sailing, set the remote
control lever in neutral. Not doing so WILL
introduce slippage and void your warranty.

I think this is to prevent the prop turning the shaft. This won't be a problem when motor sailing as the engine will be turning the shaft. Occasionally our prop hasn't folded correctly and we notice a whirring noise from the sail drive. We engage forward on the control and the prop closes and ceases to turn the shaft.

NOTICE: Running for long periods at low
rpm with the Sail-Drive engaged can cause
slipping and premature wear of the cone
clutch.


I haven't noticed this statement in the sd20 or sd60 manual. Maybe check it. Yes of course you will need to be able to motor for long periods at low revs. We usually motor on one engine at around 2100rpm using 2l of fuel at 5K

Is it possible to motorsail with SD50 sail-drives and not damage or cause excess wear on the clutch and drive shaft?

Maybe you will get lucky..maybe not. Personally I'd be considering the replacement cost in the purchase price with the view to changing to sd60s if they become a problem.
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Old 28-01-2015, 07:05   #3
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Re: I am so confused – too much information here

The SD50 is an ok unit but it does require some additional maintenance on the cone clutches, so you should manage your own expectations in that regard. As long as you are willing to accept that, and keep up with it, I don't think there is any reason to avoid a boat with the unit.

Only the SD20 line really needs to be hauled for a quick, one drain oil change. The SD 40/50/60 can be changed in the water with commonly available tools.
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Old 28-01-2015, 08:33   #4
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Re: I am so confused – too much information here

Quote:
Originally Posted by TacomaSailor View Post
Are the Yanmar SD50 sail-drives a potential problem or are they a stable and useful drive unit when well maintained?

Yes, they are a problem. The SD40 and SD50 cone clutches are notoriously bad. The SD40 was so bad that they axed it for the SD50, which was supposed to solve the problem. The SD50 was worse. Yanmar attempted to "fix" the problem by requiring that the clutches be pulled and lapped every 250hrs as routine maintenance. This is absurd. For comparison, Volvo saildrives make no mention of any maintenance on their cone clutches, and searching the internet for Volvo cone clutch issues returns mostly a big blank.

Yanmar has now moved onto the SD60, which is a plate-clutch (not a dog clutch). This should solve the problem. Volvo has also switched to plate clutches. They had slipping/burning problems in the very early ones and found that they specified the wrong type of oil for them. Changing the oil type seems to have fixed the issue for them, and I'm sure Yanmar has learned from that.


A second question is about oil changes in the Yanmar sail-drives:

Is it really necessary to haul the boat out of the water (or put the boat on the beach on it’s keels) to change the SD50 sail-drive oil?

There should be no problems with the internal oil change system. I don't know why you were told that the boat needed to be hauled - Yanmar specifically describes changing the oil internally as routine in its user and maintenance manuals.

A third question is about motor sailing:

The Yanmar Sail-Drive operation manual says:
NOTICE: When sailing, set the remote
control lever in neutral. Not doing so WILL
introduce slippage and void your warranty.

NOTICE: Running for long periods at low
rpm with the Sail-Drive engaged can cause
slipping and premature wear of the cone
clutch.


Is it possible to motorsail with SD50 sail-drives and not damage or cause excess wear on the clutch and drive shaft?
I can't see why there would be any problem at all with motorsailing. I think the second warning is referring to low loads at low rpms keeping the cone from being thrust fully into its mating surface - which is what happens when a load is put on the prop. So in other words, they are warning against long-term putting around at 1,000-1,500 RPM - which is probably something you won't be doing anyway.

As for which gear to remain in - I think that is dependent on the prop. Folding props can be put in reverse gear with no issue. Fixed props should be left in neutral (although I don't think reverse gear will hurt it any). Forward gear should never be used to lock any prop.

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