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Tiller/Rudder pressure


Richardcn

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Nick is on to something here.

 

if using a dividing rudder! the water that goes straight back is pushing the boat straight forward, but the boat is turning, so the straight part of the prop wash get a vector that is counter productive.

 

a balanced rudder cover more of the prop disc and more force is going into turning the boat, or less rudder angle is needed. for the same turn rate.

 

a better shaped rudder will turn most of the prop wash as well as the free streaming water, without it Stall, the rudder.

see Schilling rudder...

There is no argument about that. The question really is, is the water more useful being diverted into a turning motion or left to continue giving the boat forward propulsion. (strictly in the balance or no balance argument).

 

Fitting a completely different rudder design is a new ball game and I have no doubts the old lads would have embraced anything that speeded them up. Time definitely was money to them.

 

George ex nb Alton retired

Edited by furnessvale
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Fair enough Nick.

 

I bow to the superior knowledge imparted by the SMH school of motoring boating.

 

George ex nb Alton retired

No need to get sarky! FYI SMH boats have much less counterbalancing than most, the boat just wants to go straight ahead and the rudder forces are quite high especially with plenty of power on. You can't just move the tiller hard over, it takes a couple of seconds unless there is a real crisis and adrenalin kicks in! Other boats I have driven are flighty and if you stop "driving" let alone take your hand off the tiller for a moment, they are off into the bushes quick time.

 

I like the feel of our heavier tiller and so if you want to tell me that the old lads liked no or minimal counterbalancing because it made the boat easier to steer (because most of the time is spent going more or less straight) I can certainly go along with that. I just can't accept that it is somehow more efficient.

Edited by nicknorman
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No need to get sarky! FYI SMH boats have much less counterbalancing than most, the boat just wants to go straight ahead and the rudder forces are quite high especially with plenty of power on. You can't just move the tiller hard over, it takes a couple of seconds unless there is a real crisis and adrenalin kicks in! Other boats I have driven are flighty and if you stop "driving" let alone take your hand off the tiller for a moment, they are off into the bushes quick time.

 

I like the feel of our heavier tiller and so if you want to tell me that the old lads liked no or minimal counterbalancing because it made the boat easier to steer (because most of the time is spent going more or less straight) I can certainly go along with that. I just can't accept that it is somehow more efficient.

Would I get sarky with the man who has never been known to knock (ex)working boats or their owners!cheers.gif

 

George ex nb Alton retired

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George have one point coming up.

 

with a heavy rudder it will likely not be slammed at the stop, but the angle will be gradually increased with increased turning rate and reduced speed.

 

an well? balanced rudder can easily be put at an angle where the rudder blade is stalled (the water is not following the suction side of the blade)

 

and this is what it is all about the drag!

 

for a given turn rate we can assume the added drag on the boat is the same witch rudder we ever use.

but a rudder that is stalled ad more drag then an not stalled rudder.

 

The stall angle is in relation to the incoming water, so say the rudder is held fixed at 15 degree, the angle to the incoming water depends on the turn rate of the boat.

Edited by Dalslandia
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