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Rudder to prop clearance?

I'm hoping to improve the balance of my tiller and the response to tiller movement by adding an inch or two to the forward edge of the rudder but don't know what the minimum clearance between prop and rudder should be.
Any help much appreciated.

Asked by: Rob Pendleton  | 12.17am, Monday 12 December

WW says:

As you are already aware the deciding factor as to the size of a balancing plate in front of the pivot point of any rudder is the distance from the propeller. The best steering performance is with the leading edge of the rudder close to the propeller but a gap is important. There is always debris in canal water and if the rudder is too close bits flying off the propeller can make the rudder twitch, or in extreme cases jam. A gap of about 50mm will allow any debris to disperse easily.
Be wary of making the balance plate too large as it can make the rudder move by itself with the flow of water and the self-centring action can be lost.

Rupert Smedley  | 11.11AM, Monday 12 December

Can you send the photo to

Rupert Smedley  | 3.24PM, Monday 12 December

Readers say:

Many thanks for all the advice.
I have a photo of the rudder and prop when she was in a dry dock recently, but can't attach it here.

Rob Pendleton  | 2.31PM, Monday 12 December

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