straight v's tapered blade

[Luca Gray]

Guy's what is the difference between running straight blade(cmdi) verse's tapered blade(speedmaster)

on an outrigger, doe's one make more left, difference in handling etc

thanks

cheers Luca

 

[namba969]

I might be wrong but I think tapered blades add lift to the back of the boat. That's why most riggers run a straight blade... some even have the bottom rounded to help reduce lift. Hope I helped!!!

Andrew Grenier

 

[Terry Keeley]

I might be wrong but I think tapered blades add lift to the back of the boat. That's why most riggers run a straight blade... some even have the bottom rounded to help reduce lift. Hope I helped!!!

Andrew Grenier

I've found the same and run the bottom of the rudder dead flat.

 

[Charles Perdue]

I run the bottom of my rudders dead flat also.

Think about it for a minute, the flat bottom of the rudder can not be a planing surface until it has an angle of attack above 0 degrees. However.......if the bottom of the rudder is rounded, when the rudder is moved from dead straight, the water flowing by the curved bottom is trying to lift the rudder by pushing up on the curved bottom of the rudder blade. Just the opposite effect from what you were trying to accomplish.

 

[Marty Davis]

I run the bottom of my rudders dead flat also.

Think about it for a minute, the flat bottom of the rudder can not be a planing surface until it has an angle of attack above 0 degrees. However.......if the bottom of the rudder is rounded, when the rudder is moved from dead straight, the water flowing by the curved bottom is trying to lift the rudder by pushing up on the curved bottom of the rudder blade. Just the opposite effect from what you were trying to accomplish.

Charles:

I agree with you that the flat bottom is not a lifting surface unless there is lag in the rudder blade. I round my rudder bottom for the exact reason that you indicate. I WANT it to lift the rear of the boat in the turns. It allows more turn speed and more exit speed. This is something that I found many years ago and would not have a blade without rounding.

Guess there are many different ways to get results....

 

[Charles Perdue]

Marty, we are both right, some boaters want the rear lifted in the corners and some do not. I was just trying to clear up the misconceptions between the flat bottom rudder and the round bottom rudders for some of the guys.

All is well.......

Charles

Are you going to Hobart?

 

[Terry Keeley]

Also, most hulls run at some tail high attitude, if the rudder is perpedicular to the hull how can it be a planning surface? If the nose comes up it is, but then it'll help set it right (along with the rear sponsons).

 

[Charles Perdue]

Does this mean that all 3 of us get a "Jelly Bean" today?

 

[Marty Davis]

Marty, we are both right, some boaters want the rear lifted in the corners and some do not. I was just trying to clear up the misconceptions between the flat bottom rudder and the round bottom rudders for some of the guys.

All is well.......

Charles

Are you going to Hobart?

Your analysis is right on.... It is the first time that I have seen anyone post that analysis But, I am not surprised that you figured it out. B)

It depends on what you want your boat to do when you turn the rudder. Again, there are many ways to get from point a to point b.

Not sure yet on Hobart. Things are very slow for me in the Appraisal business so it is a $$$ decision.

 

[Chris Wood]

i have seen in the past some people take and cut a angle or file a angle on both sides of the bottom like a V. i personally run my flat.. i have my own reason's for that thought.

as to weither or not any of it makes a huge difference or not.. not sure

i tried rounding. grinding the bottom and flat and see zero difference.. again. on my own boat.

chris

 

[Ian Inverarity]

Guy's what is the difference between running straight blade(cmdi) verse's tapered blade(speedmaster)

on an outrigger, doe's one make more left, difference in handling etc

thanks

cheers Luca

Luca,

I have run tapered rudders on some of my riggers without noticing any problems, but I have not tried comparing straight vs tapered on the same boat.

 

[Luca Gray]

thanks for the reply's guy's

Luca