YSM12 Transmission

Steve Dion · Dec 22, 2009

The only down side of putting your transmission in reverse while sailing is the drag. I am sure that the drag with your CS vs a regular Michigan is considerable less.

If you are in doubt, put it in reverse until you get an answer from a certified Yanmar dealer that it is OKAY to sail in neutral.

Maine Sail has a presentation on the subject. But the real question would come from the mfg. I would contact the master distributor in your region for the answer.

PS: What type of speed do you normally get out of this setup? Did you have another prop on this boat before you got the Campbell?

Ron20324 · Dec 22, 2009

Jal, you've listed three different engine models and two different horsepower, and I would have to believe there could have been more than one type of transmission over the period of years this(these) engine(s) were in use. Since you can't find any mfg info on the tranny, can you get us a picture to look at? Might be the only clue left?

Bud22569 · Dec 23, 2009

I have the original YSM Operation Manual. There is no information on this question in the YSM Operation Manual.

Ed Schenck · Dec 23, 2009

I would be interested to know how it has lasted for thirty years if it is original. How did the other owner(s) sail the boat?

Hermit Scott · Dec 23, 2009

It doesn't matter if you leave it in neutral, reverse or forward becasuse of the way the gears are lubed.
I asked the same thing a week or so ago. The reason why some manufacturers tell you to put it in gear is they don't want the transmission turning without the oil pump supplying lube oil to the gears. But on the YSM the gears are lubed with the turning of the gears in a bath of oil.

Rob19574 · Dec 23, 2009

I would agree with Scott on his point above. I leave mine in neutral its its over 30 years old. MackBoring has a great tech line for Yanmars, particularly the YSM series. try giving them a call at 866.526.9717.

- Rob

Stu Jackson · Dec 23, 2009

Transmission position

Since this comes up so often, I "tagged" the last topic, the one Hermit mentioned, with the phrase "transmission position."

This is what comes up in a search for that exact phrase: http://forums.catalina.sailboatowners.com/showthread.php?p=678220&highlight=transmission position

It's a pretty good discussion in answer to your question, and should be pretty handy for the future, too. It's got some good links to other discussions.

Good luck finding the documentation you need.

Steve Dion · Dec 23, 2009

Jal: This is interesting to hear. We have a friend with the same motor in a Hunter 30. He also needs to do something about the prop. I am going to forward your information to him for evaluation and see what he says. Thanks for the input.

I believe that you will find that the "preferred" method for locking the prop is actual reverse, but if forward resolves your issues then OK!

Hermit Scott · Dec 23, 2009

Jalepeno said:
Steve:
- I have been leaving it in FWD to reduce ware on the stuffing box.

I thought about that, but if your engine is doing 3000 revolutions per minute while -powering, how many revolutions is it going to do while sailing along and letting the water spin it? I don't know, I am sure Maine Sail could tell you; he has done some testing on this subject.
But my guess is if you motored a half an hour, you would have to sail for a week straight to achinve that many revolutions of the prop shaft. And it would be at a MUCH lower RPM with much less heat to aid in wearing the stuffing box. It has to be negligible. And aparently according to a recent study you sail faster in neutral. But not everyone can sail in neutral or it kills the tranny as discussed in the link Stu provided.

panache tony · Dec 23, 2009

Jalepeno said:
I have a question regarding the transmission (reduction gear & clutch assembly) for a Yanmar YSB, YSE and/or YSM. Those that have one of these simple and reliable single cylinder horizontal diesel motors with will know that they came in both the 8HP and the 12HP variations. The transmission gears are in constant mesh and uses a wet type single-disc mechanically operated clutch using 0.7 Litre of engine oil. My Yanmar is a 1979 YSM12 with a 1.976:1 reduction ratio in both forward and reverse with a Campbell Sailor CS3LH12x7x1 propeller. Now that you have the back ground, here is the question that everybody asks but few can give an intelligent answer.

With a YSM12, should you leave the transmission in gear or in neutral when sailing?

I am not looking for a lecture about hydraulic shifted transmissions using automatic transmission fluid or look the manual or is it a Kanzaki. I have the Yanmar shop manual and nowhere in it or on the motor/transmission does it say what the transmission make or model number is other than Yanmar YSM12. I also searched on the internet and not found anything useful. I'm looking for information from YSB, YSE and/or YSM owners.

leave it in gear with the prop straight up and down for the lowest drag under sail. If you are having trouble with boat speed ,I hav aC30 and that proponly gave about 4.0 knots under power .Iswitched to a 12/10 2 blade and it worked much better panache tony

Maine Sail · Dec 23, 2009

Jalepeno said:
I have been just leaving her in FWD when I stop the motor and probably will keep doing that.

Yanmar to my knowledge has never stated in any of their manuals which position to put the gear box in for sailing. I had a Y series engine in my old C-30 and was told by Gordon Torresen to either leave it in neutral or lock it in reverse but not forward. I only found out after wards Gordon was wrong and Yanmar advises now that it should be neutral. I know of no gear box maker that suggests leaving it in forward but this does not mean some can't be locked this way I just don't know of any.

I have the entire slew of YSM manuals, including the gear box manual, in PDF form. PM me your email and I will fire them off. These manuals are like GOLD!!

If you want to lock it I would suggest reverse as Gordon suggested to me many, many years ago..

Hermit Scott · Dec 23, 2009

panache tony said:
leave it in gear with the prop straight up and down for the lowest drag under sail. If you are having trouble with boat speed ,I hav aC30 and that proponly gave about 4.0 knots under power .Iswitched to a 12/10 2 blade and it worked much better panache tony

Tony,
Do you have a YSM12 in your C30? I have been messing around with michigan 3 blade props trying to find the richt pitch. I am using a 12LH10 currently. I can motor at 5 to 5.3 pretty well even in some chop. I had a12LH11. With that I have had the boat over 6 knots in very flat water and perfecftly clean bottom and prop, after just leaving the yard. But when I hit chop, I could be doing 2 knots or worse.
what brand of prop are you using and what different props and pitches have you used?

Hermit Scott · Dec 23, 2009

Jalepeno said:
I have a question regarding the transmission (reduction gear & clutch assembly) for a Yanmar YSB, YSE and/or YSM. Those that have one of these simple and reliable single cylinder horizontal diesel motors with will know that they came in both the 8HP and the 12HP variations. The transmission gears are in constant mesh and uses a wet type single-disc mechanically operated clutch using 0.7 Litre of engine oil. My Yanmar is a 1979 YSM12 with a 1.976:1 reduction ratio in both forward and reverse with a Campbell Sailor CS3LH12x7x1 propeller. Now that you have the back ground, here is the question that everybody asks but few can give an intelligent answer.

With a YSM12, should you leave the transmission in gear or in neutral when sailing?

I am not looking for a lecture about hydraulic shifted transmissions using automatic transmission fluid or look the manual or is it a Kanzaki. I have the Yanmar shop manual and nowhere in it or on the motor/transmission does it say what the transmission make or model number is other than Yanmar YSM12. I also searched on the internet and not found anything useful. I'm looking for information from YSB, YSE and/or YSM owners.

I know the CS prop reportetly creates more thrust than a michigan prop, but that is interesting that you are using a 7" pitch! If I put a michigan 7" pitch on my boat I suspect I would find top speed at 3 knots, but could plow through the perfect storm at 3 knots also. Those CS props are definitely a different animal.

Hermit Scott · Dec 24, 2009

I have the exact same engine as you. But my boat is 10,200 lbs. soemthing like 26' on the water, 11' across the beam. (Not exact but close)
what kind of speed are you getting with your new prop?
I scuba so, my prop changes are free. Except it's getting a bit cold with out a wet suit for me.