Torque roll

[James McDermott]

Hey everyone

I'm pretty new to rc boating but not rc been into rc cars for years

Im having an issue with torque roll. I'm running a joysway ul-1 catamaran it's about 27" long with the rudder in the centre and 2 4200 4s in parallel. Both battery's sit in the same spot on each sponson.

If I get on the throttle the boat will start tracking right as it picks up speed, when I turn right it turns like its on rails but and any left hand input it'll pick the left sponson up and want to roll.

If I offset set the rudder to the right will it help counteract the roll? Should I offset the weight on each side too?
My front to back COG is around 31%

[lenny]

Post some pictures of your boat and setup,
Or do you have a link to the boat ?
What prop are you using on it ?

[James McDermott]

http://www.atomik-rc.com/Joysway-US-1-ARR-Brushless-RC-Boat.html?sc=31&category=455784

This is the boat I'm running
But I've moved the offset rudder to a centre rudder and wired in 4s is parallel
The prop is 1.4 pitch with 40mm diameter

[James McDermott]

image.jpgimage.jpg

[lenny]

Ok you have this boat,
A lot better pictures hear of the stock boat.

http://www.ujtoys.com/Joysway-8302-Catamaran-US1-RC-Speed-Boat-White-p/j-8302-w.htm

I would like to see some video's of how your boat is riding on the water.

Also it sounds like you are getting prop walk,
I would try moving the cells back about 6" and see what it does for the ride.
And with the tracking to the right in the straights.

Is your prop in good shape ?

Also is you strut adjustable ?
If so you could try moving it level with the bottom of the sponsons,
By laying the hull on the edge of a flat table and adjusting it with the prop off and rudder hanging off the edge.

I would also try a S&B x440/3 prop out on it and maybe a x437/3 to,
The three blade props help make a boat ride a lot smoother I have found.
And also helps a lot with torque roll to.

You could also tapper the bottom of the rudder with a file,
To help stop with lift from a flat surface to.

[James McDermott]

ill move the cells back 6"

the props brand new
the strut is adjustable ill try moving it level with the sponson and give it a run tomorrow

with the props the drive shafts only 1/8th can you supply a link to where i can buy the x440 and x437/3 with sleaves if needed

also do i taper the leading edge of the rudder to the trailing end and finaly should i re offset the rudder?

[martin]

These hulls are intended to run 1 battery which fits into the left side of the hull, left side is used to counter torque. You have added weight to the right side with the second battery helping increase torque roll, probably why your boat is pulling to the right under power as well because of the weight added to the right side of the boat.

[James McDermott]

yeh i understand that could i then offset the position of the batterys?

[martin]

Switch the rudder back to offset, it will turn better.

[lenny]

I think offset rudders to the right help with some cats,
You can make a spacer for the 3/16 props or buy one.
http://www.offshoreelectrics.com/pro...?prod=ose-1035
Prop do a WTB or http://www.offshoreelectrics.com/
http://www.offshoreelectrics.com/pro...Balanced+Props

Tony H rudder mod.
DSC03156.JPG

Some reading iffo that may help with that cat of yours.
http://forums.offshoreelectrics.com/...at-Sprint-race

[martin]

Theirs a reason why joysway offset the rudder on this boat when they could of simply fitted the inline rudder off of the Bullet mono which is what you have ended up with.

[James McDermott]

yeh ive kinda realised that.. i was thinking one battery on left then offset rudder on right but two batterys then centre rudder.. considering the rudder mount had holes for the strut


okay awesome ill have a test tomorrow and see how i go.

[martin]

To stop any confusion that is a US 1, the UL 1 is a hydro from Aquacraft.

[James McDermott]

sorry my bad been looking at the ul1 today was kinda stuck in my head

[ReddyWatts]

Is there a reason why your running the prop backwards?