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-   -   Significant Port helm while under power (https://www.cruisersforum.com/forums/f47/significant-port-helm-while-under-power-152689.html)

desodave 09-09-2015 09:56

Re: Significant Port helm while under power
 
There is a Hunter forum at;

SailboatOwners.com

if you wish to pursue it further, especially for the issue of design flaws in the 356

Cadence 09-09-2015 10:04

Re: Significant Port helm while under power
 
Quote:

Originally Posted by AnchorageGuy (Post 1910774)
So true. I have commissioned dozens of these right from the factory. Not an impressive boat. Wait until all the other issues start to surface. Chuck

Chuck,

You may want to tell of what other issues? It may help on the buying decision or after that, if bought. PM him if you hadn't.

He can take it or leave it.

Roger

ex-12m-guy 09-09-2015 13:21

Re: Significant Port helm while under power
 
We had a similar situation with our Hunter 34. Under power, it was necessary to "fight" the wheel constantly to keep the boat going straight.

The cure turned out to be simple. We tightened up the steering friction clamp just enough to keep the wheel from moving when powering ahead "hands off." There was only a slight bit of extra drag on the wheel when maneuvering, hardly noticeable.

Turned out the extra steering wheel drag was also helpful while under sail, so we did not bother to change the setting when switching between sail and power modes.

Another bonus was when backing up under power. The wheel could be set to counteract prop walk, and the boat would back straight as an arrow, hands off.

We did not have an autopilot. However, it makes sense that the extra friction should be removed when the autopilot is in charge.

MarkSF 09-09-2015 13:47

Re: Significant Port helm while under power
 
Look at this picture and the cause of the prop walk is obvious - the angled prop shaft. Imagine the interation between that angled prop and the water moving at speed past it.

2002 Hunter 356 Sail Boat For Sale - www.yachtworld.com

RichandHelen 09-09-2015 15:39

Re: Significant Port helm while under power
 
Quote:

Originally Posted by MarkSF (Post 1910929)
Look at this picture and the cause of the prop walk is obvious - the angled prop shaft. Imagine the interation between that angled prop and the water moving at speed past it.

2002 Hunter 356 Sail Boat For Sale - www.yachtworld.com

Isn't that the same setup for ANY boat that is not a sail drive?

a64pilot 09-09-2015 16:19

Re: Significant Port helm while under power
 
Quote:

Originally Posted by Cadence (Post 1910784)
Chuck,

You may want to tell of what other issues? It may help on the buying decision or after that, if bought. PM him if you hadn't.

He can take it or leave it.

Roger


Strongly advise you to get on the Hunter Owners forum.
I bought a 356, a beautiful very well maintained boat, it failed survey on exactly what the owners forum told me to look for, and I pointed out the hull defect to the surveyor who hadn't noticed it, and I wouldn't have either, except the good folks on the owners forum told me exactly what to look for.
They and I assume Owners Forums in general are a wealth of information


Sent from my iPad using Cruisers Sailing Forum

AnchorageGuy 09-09-2015 17:20

Re: Significant Port helm while under power
 
I agree that all the information you could ask for can be found at the owners forum on sailboatowners.com. Chuck

GrahamHO 09-09-2015 20:46

Re: Significant Port helm while under power
 
It sounds like torque reaction or more simply "prop walk." The propellor is like a wheel moving the stern of your boat sideways. So if the prop is rotating clockwise viewed from astern it will be walking the stern to starboard and the bow will point to port. The further astern the prop, the more noticible this effect is. The propellor has more grip at its deeper point where the water is at higher pressure. It's quite normal. Racing outboard boats can have twin engines with the props going opposite directions to cancel this out.

You can't change it. Any propellor will do the same thing.

High performance propellor aircraft like the Spitfire or Mustang did a similar thing on take off especially, as the plane tried to rotate around the propellor the pilots had to correct with the controls.


Volvo has a dual prop for their large powerboat engines with 2 propellors on the same axis rotating in opposite directions to cancel this effect out. Some aircraft also used counter rotating propellors. Helicopters try to rotate around the rotor blades. That's why they have a tail rotor to counteract the effect. And that's how they turn left or right by reducing or increasing the pitch of the tail rotor.


On my own boat when I'm motoring if I don't use the autohelm or tie the tiller it will turn if I let the tiller go even though my propellor is about 8' in front of the rudder.



Prop walk can be used to your advantage when you are docking. It will steer the stern one direction going forward and the opposite way in reverse.


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