Stopping prop free wheeling?

[Paul P]

Hi, my B40 has a 4JH4AE and I'm not sure what transmission I have (I'll check soon). I've been putting the trans in rev while sailing to stop the prop from spinning. If I read correctly somewhere I shouldn't be doing this with a yanmar. I've been doing it for a while on my old C&C with a Universal engine and tranny. Any wisdom or suggestions

Thanks

Paul

[Mike Brown]

I have the same engine in our 43 and have also read the same comment. I've asked the dealer's service manager as well as Yanmar techs at a couple of the shows and everyone has said it's not an issue to leave it in reverse as long as you're not sailing for hours on end. And by hours on end they mean more like days on end. Until I hear otherwise from a reliable source I'm putting her in reverse.

Mike

[James Taylor]

Yanmar issued an advisory to owners of 4jh4ae engines to select neutral position when engine is off and sailing .  They make clear they will not be responsible for transmission or engine damage sustained through improper gear selection while sailing with engine in off position.Enclosed is Yanmar's Advisory Number: MSA08-003:I dated Feb 2008 for all sailboats with Yanmar engines.

http://www.mainehuntersailing.com/files/2010Files/2010Newsletters/2...

[Michael Boyle]

Hi Paul, not sure if this is wisdom but on my 43 (with standard line prop not a saildrive) with a 4JH5E and a KM35P gear box hand book says do not put the drive into gear at more than 8 knots (not often that happens). Before we fitted a Kiwi folding prop I would put drive into reverse when ever sailing--even though it applied more resistance then free wheeling--just because of the noise of the prop turning. I would always have to flick the starter to get the morse control to move back into neutral. I couldn't get any definative answer to whether the practice caused any problems with the gear box from supplier or local marine engineers most of whom said that they did the same. My simple engineering view is that the gearbox is designed for transmission of loads both forward and reverse that must be higher than the loads imposed by the flow of water over a fixed prop. Consider the loads when motoring in a choppy seaway compared to the load when sailing. Since fitting the Kiwi on occasions the blades would stick and the prop start to free wheel I have then put it into reverse, prop stops and I asume blades fold but still the morse will not come out of gear. I can only assume that any slight load will cause the gear shift to stick when the engine is not operating. Flicking the starter cures the stickness. My reckoning is that if there is an eight knot limit below that speed then Yanmar and gearbox manufacturer must be happy that the practice is within the design of the combination. Not wisdom or suggestion just an observation for stand prop configuration.

Good sailing (sailing in UK has been pretty miserable this summer)

Michael

[Paul P]

Thanks Micheal, I added a little more info below but I am interested in knowing your opinion on the kiwi prop? You must have the largest one they sell? What are you getting for speed and fuel burn, also how's reverse?

[Paul P]

So I took advantage of the link from James and called Yanmar this morning to confirm that their advisory was still in affect. I checked and I also have a KM35P transmission. The gentleman I talked with says it still applies to my trany and he was a little weary to say that it was ok for the prop to be left in neutral and spin but he eventually said it is better than in gear while sailing. His explanation was basically that the gearbox has clutch plates that tend to lock when put in gear while sailing. It is when we try to go back to neutral or start the engine that it could cause damage to the clutch plates. He suggests using alternate methods to stop freewheeling to ensure no problems. I have also been using reverse to stop the spinning but I was under the impression that the spinning was worse of an issue. And I also have had to use the starter to unlock the shifter. Well I think its time to crack the wallet and order a feathering prop. At least I got a story to justify it to the wife!!  Thanks for the help.

[Mike Brown]

James, thanks for sharing the Yanmar notice. Paul's note seems to clarify the issue with the focus being on forcing it into or out of gear while sailing. I always slow down to the point I can take it out of reverse or if still locked a speed that will allow me to start the engine without placing undue strain on the transmission. Mind you slowing down means more like coming to an almost complete stop. Not really an issue since I often heave to to furl the main.

Mike

[Michael Boyle]

Hi Paul, lots od differing advice on the question of using reverse for stopping prop. one of the key factors is whether you have normal prop or sail drive, definitely if a sail drive then there is the possibilty of jamming the drive cones (I don't think they are plates) although when I had a sail drive on another boat (a Moody 40) I still stuck it in reverse and flicked it out with a start of the engine. However  locking the prop causes more resistance and slows you down more than a free wheeling prop.

The Kiwi prop when it arrived I thought was incredibly small with blades that where about a third of the size of the fitted fixed prop. It was well made with stainless hub and the supplier sized it---the largest they do at 18.5inches diameter--and also adjusted the pitch, they call it the angle, to the maximum.

However when it was fitted I haven't notice any difference with the speed forward or the fuel consumption although I haven't undertaken any extensive comparisions or calibrations, she still handles the same and is doing about 3.82litres per hour. (One fill of tank at middle of season, last year it was 3.7 and 3.95 when I filled tank). reverse seems to be even more effective because the pitch is at maximum when engageing reverse. I have had a couple of occassions when it hasn't feathered and I just dropped it into reverse and the shaft stopped. I think that we are probably getting between 1/2 and 3/4 of a knot more under sail but it is difficult to accurately know with changing conditions. Besides that I have to convince myself and first mate that it was worth it. The real worth is that when we are sailing it is quiet.

There was a report comparing folding and feathering props done by Practical Boat Owner last year which I am sure if you search net will show up, the Kiwi wasn't the best but was half the price.

So far we are very pleased with it.

 

Michael