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Old 08-28-2003
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prop drag while sailing

I read somewhere that it creates less drag while sailing if the transmission is put in reverse so the prop is unable to turn, then to leave the transmission in nuetral so the prop freewheels. It is supposedly less harmful to the transmission also.
Can any well trained boat mechanics back this claim and does it really create less drag?
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Old 08-29-2003
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prop drag while sailing

Probably three or four years ago there was a widely quoted study of propeller drag. The finding basically said that a two blade propeller locked in the vertical position had less drag than one permitted to spin. Under certain circumstances a three blad prop that was allowed to spin had less drag than one that was locked off. The test showed that as resistance was added to the shaft slowing it from the speed that it inherently wanted to turn, turbulance increased very quickly increasing drag meaning that the free-wheeling propellor offered a lot more resistance. The test results showed that a three blade prop locked off in the ''Mickey Mouse'' position had less drag than one in any other position.

Some transmissions are totally unsuited to being allowed to freewheel because they use a engine driven power input shaft driven lube oil pump. Most smaller transmissions do not have lube problems but you are increasing the wear on the output shaft seal, internal bearings and bushing and seals, shaft stuffing box and cutless bearing, not to mention the annoying shake rattle and roll.

Respectfully,
Jeff
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Old 08-29-2003
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prop drag while sailing

When sailing my Catalina 320, I can watch my knotmeter climb approx .5 knots when I drop the gear into Reverse from neutral (and lock the prop). In addition to better wear-n-tear on the shaft, it''s easy for me to see the improved efficiency as well.
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Old 08-29-2003
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prop drag while sailing

Thanks to all for your responses. Hopefully, your insights will save me some maintenance problems down the road.

Thanks again,
Owen C.
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Old 09-01-2003
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prop drag while sailing

Volvo manual says lock in reverse when under sail to avoid transmission damage.
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