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Old 15-11-2010, 21:41   #1
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Is in Gear or Neutral Best for Engine and Gearbox when Sailing ?

Not arguing about what causes the most drag. But it seems like our volvo 40 gets a hydraulic lock and wont turn over sometimes. This caused the starter motor to smoke. I was told I need to run it in N when sailing. If I leave it in gear something will allow water to be pumped into the exhaust valves? But I cant see how this could happen?
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Old 16-11-2010, 07:22   #2
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Water in the cylinders is usually caused by poor exhaust design or by having a scoop on the intake which can force water in past the impeller. The water then passes through the raw water system and fills up the exhaust muffler and back fills into the engine through the open exhaust valve. The prop being locked or turning wont have anything to do with this.
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Old 16-11-2010, 07:31   #3
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My donk is in astern when I go sailing. Generally I have the motor off at the time
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Old 16-11-2010, 08:20   #4
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It highly depends on type of trans and how it gets lubricated... My Yanmar 1GM manual states to sail with tranny in reverse..
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Old 16-11-2010, 08:49   #5
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I was once told that locking the prop in reverse was the most efficient but from my experience (and I've also seen a video demo) I am 100% certain that drag is minimised by freewheeling the prop in neutral. On most boats I've sailed recently, speed seems to drop by about half a knot in lighter airs when reverse is selected.

Of course there are downsides in freewheeling. Firstly there will be more wear on bearings in the transmission system, plus cutlass etc., often there is a noise problem in aft cabins and some gearboxes rely on the engine running to lubricate them, which won't happen in neutral.

So what do I do? I am prepared to accept a little less speed in lighter airs, so I lock the gear in reverse as the potential damage and consequent cost of freewheeling could be high.
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Old 16-11-2010, 09:32   #6
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Quote:
Originally Posted by MarkJ View Post
My donk is in astern when I go sailing. Generally I have the motor off at the time
I've tried it with the motor on, it's bad for boatspeed.
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Old 16-11-2010, 09:42   #7
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I sailed my Columbia with the tranny in reverse. When it N, or F the motor would spin. I sail my cat with saildrives in N........i2f
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Old 16-11-2010, 16:24   #8
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I was using R. As you say F would still spin the prop. The water intake is on the side of the keel, there is no scoop.
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