off centre rudder

[bradford-design]

Since I am new to this could someone answer the follwing questions:

why on suraface drives are most of the rudders run off centre?

what effect does this ahev on the running of the boats?

what role does a turn fin play?

thanks

 

[Don Templeton]

Bradford,

If your talking about an outrigger hydro, because of our counter

clockwise prop rotation we always race in a clockwise direction.

These boats are not ment to turn left. As far as the rudder placement,

there are a lot of different thoughts about that and you will see

them mounted center, left or right. The turn "Fin" is a whole different

ball game. These boats are ment to run on 3 points. The trailing edge

or very back of the front sponsons and one blade of the prop. The

hull is out of the water and has no V bottom in the water to keep it

in line. If you try to turn with no turn fin up front the boat will slide

sideways and be out of controll. If you put the fin on the left sponsion

it will flip over in a fast turn to the right. If you put it in the center of

the boat the faster you go in a turn the more it will want to flip. If

you put it out on the right sponson it grabs the water just like

if you had a string tied to it and swung it around in circles. If you had

the string tied to the center line of the the boat and one to the transom

it would swing on it's side. if you tied the front string to the right sponson, it would swing level. I prefer to mount my rudder to the

right side of the transom for the same reason.

We also will bend the bottom of our turn fins to the left at the water line to give it even more grip.

Hope the clears things up. :

Anyway, welcome to the forum.

Don

 

[Dougster]

Hi Bradford,

In addition, you want to have the rudder blade run in clean water, and not placed behind the wash of the prop. The rudder blade will have a greater bite in clean water, and if you have a water pick-up on your rudder blade, you will get a better stream of water to your motor, without all the air bubbles that you would get if the blade was behind the prop. Hope this helps you.

 

[jklimpel]

....on V-Hulls....sometimes it simply comes down to what looks better. Strudders, although very effective for all-around performance, are butt-ugly(unless your boat is 50"+)...and stick out 4" from the transom.

A strut, and an offset rudder can look much better.

On a powerful (or overpowered) boat, a fin is usually pretty handy at 60% stern to keep it from rolling over while turning....otherwise...it will tend to 'slide' or yaw. (and then grab and flip)

You can bolt them on the transom....but thats pretty useless on a V.