Thin Stainless Rudder??

[Blackout]

Winter is here, so have been thinking. I'm building a second 20 rigger (another Zippkit JAE) for next season and was thinking about some changes. Since very little water cooling is needed for NR engines, I might ditch the standard water cooling pickup rudder for a thin stainless rudder, and figure out another way to get water to the engine. Any thoughts?? Thanks!

Is there speed to be gained from running a sharp thinner rudder?

 

[jayt]

A small amount of speed increase can be expected from running a thin blade, the faster the boat the greater the increase. You want to use a true wedge-shaped blade, the best are actual knife blades with a wedge shape - not hollow ground or blades with a sharp edge on a thicker blade front. I've seen a couple miles per hour increase on SAW boats running over 80 mph. Just make sure the blade is big enough to control prop walk.

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[Neil LaGarry]

I have seen a water pickup on. The right sponson.

 

[gil sonsino]

This is what I did on my Jae Fe....improved speed in few mph's. Gill

 

[Blackout]

This is what I did on my Jae Fe....improved speed in few mph's. Gill

How thick is that rudder?

Is there any advantage to rounding the trailing edge of the rudder? Or is the flow of water over the rudder different than the flow of air over a rudder? I know this has been discussed before, but for the life of me, the search function does not work too well for me.

Thanks.

 

[shoboat]

Craig,

For heat racing I think you will find out very quickly how the flat

rudder works or doesn't? I have tested some on a few 12 Hydros

and it was not the way to go for me. Heat racing is all about consistent

lap times not straight line speed. You will give up some handling with a flat

rudder blade.

Thanks,

Mark Sholund

 

[Mark Stein]

This is what I did on my Jae Fe....improved speed in few mph's. Gill

How thick is that rudder?

Is there any advantage to rounding the trailing edge of the rudder? Or is the flow of water over the rudder different than the flow of air over a rudder? I know this has been discussed before, but for the life of me, the search function does not work too well for me.

Thanks.

Do not round the rear edge of a rudder. A sharp edge allows the water to break free at the trailing edge. This ventilation effect reduces drag on the rudder. this is the very short version of what happens

Airplane flight surfaces rely on the air over the surfaces recombining on the trailing edges to make the wing or rudder more effecient

 

[gil sonsino]

This blade is 2mm thick and I agree with Mark as this is a saw set up.Gill