Prop: Spin or not?

[Brad Stone]

I've noticed while under sail, engine off, my prop spins merrily away. I'm wondering, from a speed perspective, if it's better to let it spin, or to "lock it up," by putting the transmission in gear. Also, are there positive or negative effects on the transmission, locked-up or not? All opinions, from common sense to incredibly complicated hydrodynamic theory, are most welcome. Thanks.

 

[Steve Dion]

Probably better to put her in reverse!

Brad:The general concensus is that you should put the transmission in reverse. If you want to read a LOT about the subject, look in the archives for this subject. There did NOT seem to be any negative effects of locking the transmission in reverse. The only major point was the fact that some transmissions were difficult to get out of gear while sailing.

 

[Jim Beacham]

put in reverse

I have a Yanmar and was advised by Hunter to sail with transmission in reverse to eliminate the free spin. Practical Sailer did an article about the debate of free spin vs locked several years ago but I can't remember the results. I figured since Hunter advised me to lock in reverse to save on the wear and tear of the transmission it was more important than a fraction of a knot in speed.

 

[Brian Ranniger]

A-4 ?

If you have an A-4 engine you can't lock it in reverse since there's no detent. I've also wondered. I've been putting mine in forward since it will stay locked there.

 

[Don Alexander]

Helicopters

The question of whether a spinning prop or a fixed one creates most drag is the question everyone wants an answer to.An autogyro, or a helicopter with a failed engine, each allow their rotors to rotate freely. This way they "glide".With the rotor locked they fall like a stone.On the other hand an aircraft with a duff engine feathers its prop in line with the airflow so it does not spin. This is the least drag configuration.Of course it largely depends on the pitch of the prop and boat propellors fall somewhere between helicopters and aircraft props.In short it depends upon individual circumstances and I have never been able to tell from comparing my boatspeed with others which is best.Professor Marchaj's book says fix them.Regards,

 

[Brad Stone]

Thanks All!

I'm locked in reverse, and locked into this great site. As always, your timely responses are most helpful! Brad