Quote:
Originally Posted by jrc
I've seen boat motors on muffs and sometimes the prop will turn while in neutral. I don't think there is any force while that is happening, but I don't want to find out.
In this case there wasn't much I could do, he wasn't that close to the props or I would have shut down. Short of that I was just trying to do what I could to not escalate the situation. If I shut down my engines, things would have got messy in a real hurry. There was a good strong current in the channel this weekend.
Why don't I "just say no" to the channel. I really don't have to go to Paugus Bay, there is plenty of other lake out there.
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I am pretty sure the prop spinning in neutral is only something you'd see on drives with shift dogs, such as you'd find on most outboards and all Mercruiser Alpha drives. The shift dogs spin on the driven shaft while the engine is running and get the oil moving. The moving oil hits the nearby shift dogs on the propeller shaft and imparts a little energy on them, making them spin the prop shaft slowly. The speed of the prop would likely be proportional to the viscosity of the gear oil and the speed of the engine. Hot and/or well-used gear oil will spin less than cold and/or brand new oil.
Motorcycle transmissions also use shift dogs and do exactly the same thing, if the rear wheel is off the ground. Since they use the engine oil in the transmission, the effect is dramatically reduced if the engine is hot.