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Old 10-02-2009, 15:06   #1
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Question prop shaft down angle of 12 (+)

may this be acceptable for a relatively heavy cruising monohull ?
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Old 10-02-2009, 15:50   #2
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Quote:
may this be acceptable for a relatively heavy cruising monohull ?
I'm not aware that it could make any difference at all or at least as one small bit of information goes.
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Old 10-02-2009, 16:08   #3
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Usually engines have a tolerance of 15 degrees. So if your shaft and engine are directly in line it should be acceptable.
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Old 10-02-2009, 16:26   #4
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And here was me worrying about 4deg on mine without using a down angle box

There is an 8deg down angle gearbox, this would reduce the engine angle

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Old 11-02-2009, 00:42   #5
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Question I should be more specific, sorry (+)

this is an electric drive, so there is no gearbox;
prop shaft is connected directly to motor shaft.

Will efficiency loss be significant if this system down angle is 12 ?

And: may some nowadays propellers (feathering or like)
partially compensate such loss ?
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Old 11-02-2009, 02:18   #6
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I would think there must be some efficiency lost....but I suppose its like so many other aspects of a boat and would depend.
Hull shape
Hull speed
Prop shape
Prop speed
Do you have a choice? If not....Its fine!
Mine is about 3.5% but I see lots of tranys at around 8% so that degree is not uncommon....doesn’t mean its efficient though.
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