What side to mount rudder on?

[kfxguy]

So I've been thinking. This Rivercat I'm building is just for straight line speed only. It's a single drive and the left side of the boat wants to lift the left side naturally. Instead of adding weight to the left or compensating some other way, I could mount the rudder and servo on the left. Doesn't the boat pull to the right also? Wouldn't mounting the rudder on the left be better for straight line running? Before I go drilling holes I want to hear from you guys and see what you think.....

[NativePaul]

I think so, I put it on the left on my straight line cat, but it is the only narrow cat I have and I haven't tried it on the right to compare.

[TRUCKPULL]

Is it the front or rear left that wants to lift?

Larry

[kfxguy]

Is it the front or rear left that wants to lift?

Larry

You know, the boat rolls over to one side. Lifts the left side of the hull under hard acceleration. I'm thinking if I put everything on the left side it would counteract that....

[kfxguy]

I think so, I put it on the left on my straight line cat, but it is the only narrow cat I have and I haven't tried it on the right to compare.

So does it go straight well? Does it lift the left side up? Do you have your rudder straight or some trim dialed in?

[TRUCKPULL]

I was thinking the same as Nascar.
If it is the front left, you jack up the rear right.
I had the same problem a few years ago on a hull.
I used a swept back rudder. on the right side. (leading edge angled back, rear edge straight up and down)
This type of rudder will give you some lift on the rear right, therefore giving down force on the front left.

Like this
http://www.offshoreelectrics.com/pro...d=ros-spdr-010

Larry

[kfxguy]

I was thinking the same as Nascar.
If it is the front left, you jack up the rear right.
I had the same problem a few years ago on a hull.
I used a swept back rudder. on the right side. (leading edge angled back, rear edge straight up and down)
This type of rudder will give you some lift on the rear right, therefore giving down force on the front left.

Like this
http://www.offshoreelectrics.com/pro...d=ros-spdr-010

Larry

Thanks. Not quite what I'm after tho. Basically it's the same thing every skinny straight line hull does set up as a single, it veers to the right and the whole left side of the boat raises under acceleration. My though process is this: the rudder is already in the water, right? So it's causing whatever drag it's causing. The boat wants to veer right. The rudder is on the right. Makes me think of its on the left that would help counteract that and allow less rudder input (straighter rudder more speed) to correct it. Am I right? I'm trying to avoid shimming the strut to make it go straight. Or trying to avoid shimming as much.

[TRUCKPULL]

Motor torque lifting the left side, and prop walk turning the boat to the right.

You could try the rudder on the left, to change the rudder drag from the right to the left.
You may still need to shim the right side of the strut (move the rear of the prop to the left) to counter act the prop walk.

Can you shift any weight to the left, Batteries ETC.??

Larry

[kfxguy]

Motor torque lifting the left side, and prop walk turning the boat to the right.

You could try the rudder on the left, to change the rudder drag from the right to the left.
You may still need to shim the right side of the strut (move the rear of the prop to the left) to counter act the prop walk.

Can you shift any weight to the left, Batteries ETC.??

Larry

Exactly!

The weight I wanted to shift is the servo and the rudder. The batteries being used are equal weights.

[TRUCKPULL]

Would moving the battery on the left farther forward help??

Larry

[dasboata]

What side to mount rudder on?

move your drive line/strut over 1/4" to the right put a 1/8" wedge under the strut mount to build left into the boat this will help !

[78MaicoRider]

When running 5S on my single powered cat, (almost the same hull as your rivercat) I run 3S on the left and 2S on the right. Helps greatly to avoid reverse torque barrel rolls. Also rudder on the right does NOT work best for all cats, the Insane cat gen 1 setup sheet calls out rudder to be on the left side. I would give it a shot myself. I see more to gain than not.

[kfxguy]

When running 5S on my single powered cat, (almost the same hull as your rivercat) I run 3S on the left and 2S on the right. Helps greatly to avoid reverse torque barrel rolls. Also rudder on the right does NOT work best for all cats, the Insane cat gen 1 setup sheet calls out rudder to be on the left side. I would give it a shot myself. I see more to gain than not.

Yea that's how I ran my previous Rivercat when I had an unequal cell count. Unfortunately this one is being set up to run 6s so the cells will be the same. I could run a 4s on one side and a 2s on the other but a 4s pack is jammed tight in there and I don't like messing with it if I don't have to.

Offsetting the drive: I'll pass on that. The one boat I've had with an offset drive never wanted to go straight. No matter what I did, it would either go straight at low speeds and then arc at high speeds or the other way around. Was a nightmare I didn't enjoy. So I'll pass on going through that again. I think the rudder on the left should do the trick. I never had serious torque roll or turning with the other ones anyway, just seeking to make it as efficient as possible. Less rudder trim I have to use, the faster it is.