Strut & Rudder relationship ?

• Increasing the prop distance from the transom on the strut will it actually increase the driveability ? Seems like all the gas boats run extended stinger drives that put the prop much further back from the transom.. WHY what are they gaining (mechanical advantage?)
• Extending the distance for the rudder blade from the transom affects the boat how and why? Same issue wth all the gas monos running the 4 or 6 inch standoffs on the rudders? Is there a physical advantage to doing this on these purpose built (large) hulls?
• Does the rudder need to be in front or behind the prop and why?

John Finch said:

Tony,

Having the rudder back from the transom does give an advantage in leverage in relation to the turn fin. The further back from the turn fin the more mechanical advantage to tuning the boat since the turnfin is more or less the pivot point. I have experimented with this greatly for SAW, and it does apply to heat racing as well. I have set up an electric mono with the rudder close to the transom and the boat would not turn left at all with full left rudder. Moving the rudder back a few inches the boat turns left just fine. Leverage!

I like the rudder either beside or rearward of the prop for the same reason. I had a twin nitro mono that would not turn at all with the rudder in front of the prop and very near the distance from the transom as the turn fin. No leverage. On my gas boats the prop is further back than the turn fin and then the rudder further back than the prop and everything comes into balance with good leverage for all parts concerned. I like the strut rather than the stinger because it allows for easier and more infinate adjustment. Set the driveshaft a little right of centerline (maybe 1/4 inch or so)where it comes out of the transom and the prop lift on the right side will help counteract torque roll for a smooth chine walk free ride.

Click to expand...

John Finch said:

Tony,

Having the rudder back from the transom does give an advantage in leverage in relation to the turn fin. The further back from the turn fin the more mechanical advantage to tuning the boat since the turnfin is more or less the pivot point. I have experimented with this greatly for SAW, and it does apply to heat racing as well. I have set up an electric mono with the rudder close to the transom and the boat would not turn left at all with full left rudder. Moving the rudder back a few inches the boat turns left just fine. Leverage!

I like the rudder either beside or rearward of the prop for the same reason. I had a twin nitro mono that would not turn at all with the rudder in front of the prop and very near the distance from the transom as the turn fin. No leverage. On my gas boats the prop is further back than the turn fin and then the rudder further back than the prop and everything comes into balance with good leverage for all parts concerned. I like the strut rather than the stinger because it allows for easier and more infinate adjustment. Set the driveshaft a little right of centerline (maybe 1/4 inch or so)where it comes out of the transom and the prop lift on the right side will help counteract torque roll for a smooth chine walk free ride.

Click to expand...