steering problems

[smillinjack]

46 foot Durbeck , full keel . When we are under power the prop wash is making the boat turn to the left. At half power it is hard to hold it straight and becomes a fatigue problem. Is there a trim tab or some other solution to this problem. Thanks for the help.

[Boasun]

If this is happening while going ahead then you;
A. May have an alignment problem with the shaft and the boat.
B. Rudder may be twisted or misaligned.
C. Keel is twisted.

Or to much prop for the boat and it walking the stern to stbd.

[ffiill]

Problem of course needs sorting but there is nothing like hydraulic steering with non return valves to deal with fatigue-I can sail my 10 ton 36ft yacht with my index finger!
No rudder feedback takes a bit of getting used to but other than that!

[smillinjack]

Thanks for all the info . It was a lot of help.

[svHyLyte]

You may have an assymetric rudder. The effects of this are less evident under sail but would appear as more weather helm on a port tack than a starboard tack. Under power you have more wash across the rudder. Eric and Susan Hiscock had this problem with their Dutch built yacht Wanderer IV and temporarily corrected the problem by adding a spoiler to the offending side of the rudder. They eventually had the rudder reshaped and added a small trim tab to the trailing edge that allowed them to adjust the rudder's behavior without undue influence on the overall performance of the yacht. Unfortunately, some Durbeck's were renowned for lousy handling. One of our club members had one and was frequently so out of control in the basin he was finally asked to move the yacht elsewhere for the safety of other owners' yachts.

FWIW...

[Sabreman]

We have the same problem, but not as severe. Our prop is offset to port and the prop wash kicks the boat to starboard. The resistance can be offset with 2 or 3 fingers on the wheel, but I also find that simply applying a little wheel brake works nicely too.

[RichH]

Your propeller tip is probably coming too close to the aperture and the prop probably has 'too large' a shape at the tip; all this causing constant and gross 'prop walk' as the prop tip turbulence comes in contact or impinges with aperture.
At 'moderate' prop rpm, the wheel/tiller is vibrating, doesnt it?

To help alleviate such, I'd suggest a smaller diameter prop and increase from a 3 to a 4 blade, etc. and with blades of better *eliptical* shape. You need to discuss this fully with a prop manufacturer (application engineering dept.) such as "Michigan Wheel": Homepage to get the 'best' shape for the 'clearances' of your aperture, etc. Your aperture 'may' be too small and probably should be 'enlarged'.