Prop Under Sail

[Roger]

Novice cruiser question:With an inboard, when under sail is it better to lock the prop by putting the transmission into reverse to prevent freewheeling, or to leave it in neutral? And the same question for transmission choice sitting at mooring or anchorThanks

 

[Rick]

Which transmission?

The manual for my Hurth HBW-50 on my C30 states that the transmission can be left in neutral or reverse while sailing. Other transmissions recommend never letting them freewheel. It all depends on the internal design.On mine I have found that if I shift to neutral the shaft will freewheel above 4 knots of boatspeed. Slower than that wont spin the shaft so I don't think it will matter what gear you are in while parked. I've also noticed that I can gain nearly half a knot of speed by unlocking the transmission and letting it freewheel in neutral (assuming I'm already sailing over 4kts.) So normally I sail with the tranny locked in reverse for less wear and if I am along side another boat and trying to go fast I will shift to neutral and gain a little extra speed.

 

[Dave W.]

Prop Under Sial

Roger, I have a Hurth transmission in my C30. I asked a machinist friend of mine on the dock, who also has a C30, the same question. He's torn his transmission apart and told me the Hurth uses friction plates and that in neutral the plate does nothing more than spin in the transmission fluid. He's been letting his prop spin the last serveral years without problem. I'm doing the same with mine. I've also found the boat sails faster with the prop free wheeling in neutral.

 

[Bob Sawyer]

Consider MOD Drill

If you allow your prop to free wheel while someone is in the water, even if your boat is stopped, currents will cause the prop to spin. This puts the person in the water in danger. I prefer keeping my prop in reverse for safety.

 

[Ron]

Another view

Some transmissions rely on the engine running to lubricate them. Allowing extensive freewheeling on these will significantly accelerate wear.You should consult the local dealer for your boat's engine, telling him the type of boat, year of manufacture, engine model#, and transmission type (if you can). They should be able to advise you on whether it's safe to freewheel or not.For my Catalina 320, I was advised to keep it in gear while under sail. I have a 3-blade prop, which does add extra drag, but I don't race

 

[Roger]

Another Opinion

If anyone is still tracking this question, I ran across this post on the C27/C270 forum on trailorsailor:Posted By: Captn JoeDate: 10/6/2001 8:59a.m. In Response To: Re: C-27 Propellers (Richard Weaver) Never let your shaft rotate while sailing. Put tranny in gear, reverse. M-18 Manual warns not to put in fwd! If you got a fixed prop and need that extra .009 knot, then make a mark on your shaft and when the 2 blade is vertical to the skeg put the Hurth in reverse(look via the qtr berth engine access panel to see the mark you made). This will make you somewhat more hydrodynamic for the race, but I bet better sail trim would make much more difference.