Being new to a 40.5 legend what gear does one leave the transmission in under sail. It's a Yanmar 54 hp with a KM35P transmission> My old boat went to reverse..The Yanmar I understand freewheels in neutral. Any thoughts?
proper gear position under sail
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Well that may be the "official" recommendation but it sure does make a lot of racket when freewheeling. I put mine in reverse. I find it hard it believe that not moving and applying less than 50 HP to the gears from the prop can cause damage to a transmission. It just does not make sense.
It also depends on whether you have a folding prop. I have a Max Prop and when transitioning to sail from power I shut down the engine in neutral, then shift almost in reverse so my prop feathers, then go to neutral. I suspect the Yanmar position may have to do with the transmission being difficult to shift from reverse to neutral with the engine stopped, resulting in some boats needing to restart the engine in reverse. They may not like that.
Mine is a 39 hp Yanmar w/2 blade fixed propeller. If sailing at between 1 and 3 kt (through the water speed), it's in neutral (to reduce drag) and "freewheeling." If over 3 kt it's locked in reverse, otherwise the sound and sometimes vibration is distracting. If there is a need for starting the diesel, it pops out of reverse fairly easily underway.
You are evidently aware that Yanmar sent an advisory mandating neutral. I have a folding prop, so it makes no difference. I did lock two other Yanmars in reverse for 20 years with no ill effects. So, I guess the answer is that Yanmar calls for neutral, and not everyone follows that advisory.
I did not know about the advisory. Thanks. But, it's saildrive and may not act the same as a different kind of transmission would. My Pearson had the transmission of its Universal diesel locked in reverse while sailing for over 25 yr of use.
Pushing 7 knots (motoring) or resisting 7 knots (under sail) will place similar strains on the clutches and tranny. Hunter finally came out with their official recommendations on this long standing dilemma and it is to freewheel. Personally I think the transmission and clutches are sturdy enough to withstand either practice for many, many years. Just 2 things for your considereation 1) with the propeller locked there is a drag factor which may reduce around 1/2 knot from your top speed. 2) With the transmission locked in reverse you will need to slow the boat down to under 1 knot before you can shift back to neutral. Forcing the gear lever may cause wear or damage, just listen to the thump. Some have the practice of starting the engine while the transmission is in reverse to avoid having to slow down and making it easier to shift to neutral. I personally let the tranny freewheel. The gears are in constant mesh and the bearings receive proper lubrication. Our drive shaft must be well balance as I feel very little vibration with the prop free to turn.
Food for thought
some of the gear boxes have just gears, bearings, and synconizers in there make up....others have clutch plates and disc in there make up ...i am of the mind set that if you have just gears any position would be ok ...if you have the kind that has plates and dics nutrel would be best in order to keep the ware to a minimum on the dics and plates.....that would be the only reason i can think of to keep them in nutreal
regards
woody
some of the gear boxes have just gears, bearings, and synconizers in there make up....others have clutch plates and disc in there make up ...i am of the mind set that if you have just gears any position would be ok ...if you have the kind that has plates and dics nutrel would be best in order to keep the ware to a minimum on the dics and plates.....that would be the only reason i can think of to keep them in nutreal
regards
woody
Re: Food for thought
In my case, the "vibration" sound I sometimes notice might actually be due to some kind of cavitation, not shaft vibration per se, since the saildrive has no shaft. A folding prop is in the future, however.
In my case, the "vibration" sound I sometimes notice might actually be due to some kind of cavitation, not shaft vibration per se, since the saildrive has no shaft. A folding prop is in the future, however.
Re: Food for thought
Here's some of the content from the evident advisory from 2008.
"We continue to get questions regarding the correct gear position while sailing with the engine OFF. This advisory is issued as a reminder; Yanmar requires that if sailing with the engine OFF (not running) the transmission shifter must be in the neutral position or internal damage to the gear or sail-drive will result. This damage will not be covered by Yanmar’s Limited Warranty. Please instruct customers and dealers who deliver the sailboat to the customer, of the correct (Neutral) position for the marine gear while sailing."
Here's some of the content from the evident advisory from 2008.
"We continue to get questions regarding the correct gear position while sailing with the engine OFF. This advisory is issued as a reminder; Yanmar requires that if sailing with the engine OFF (not running) the transmission shifter must be in the neutral position or internal damage to the gear or sail-drive will result. This damage will not be covered by Yanmar’s Limited Warranty. Please instruct customers and dealers who deliver the sailboat to the customer, of the correct (Neutral) position for the marine gear while sailing."
And, "King's Gambit", if you have a folder like my Flex-O-Fold then you canNOT sail in neutral. Well I guess you could but the folder wouldn't fold. In neutral you can hear the transmission whine. In the proper reverse all is quiet and the prop is folded.
Looks like the way to go to settle the issue--folding prop. Easier to justify now (but 3-sec per mile penalty!).
Not to be pouring gas on a fire but can someone tell me how a prop operating backwards can possible generate more strain than the engine?
I've seen every kind of clutch and none will be harmed unless there is slippage between the driven and driving parts. Kinda hard to believe that is happening (see first comment above)
Gears are gears and are designed to handle some max torque. The engine manufacturer selects a transmission to handle more than the engine's max torque. So I'm thinking the gears would be OK unless you hit something.
With all that said what are these "internal parts" that are being damaged?
I've seen every kind of clutch and none will be harmed unless there is slippage between the driven and driving parts. Kinda hard to believe that is happening (see first comment above)
Gears are gears and are designed to handle some max torque. The engine manufacturer selects a transmission to handle more than the engine's max torque. So I'm thinking the gears would be OK unless you hit something.
With all that said what are these "internal parts" that are being damaged?
I used to put the KM2P gearbox in reverse when I had the stock 2 blade 'cos I couldn't stand the free spinning thumping when sailing. I always had problem putting the gear back to neutral after that. So when I changed to a 3 blade, I left the gear in neutral for the 3 blade prop to spin freely while sailing as there's no more thumping sound/noise. Yanmar manual recommended gearbox to neutral when sailing.
Count me in the locked down in reverse crowd. I understand Yanmar's advisory but I have been leaving the tranny in reverse while under sail and the diesel not running for 5 years and have had no ill effects. The spinning prop only causes some noise (that for some reason I can hear and it drives me crazy) and no vibration. Regardless, I put it in reverse and leave it there. My preference.
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