Delta Force DF45 Mark 2 roll.

[Simmo]

Hey guys. I have a Delta Force DF 45 Mark 2 with the following running gear.
SSS 5684 800KV.
ZTW 300 amp ESC.
648 prop.
Running 12S (2 x 6s 4000).

Over 45-50 MPH the boat wants to pull to starboard and plane on the starboard side of the hull. The port side of the hull is completely out of the water. I have tried moving the batteries to the port side to add more weight but this makes no difference. The rudder is offset 40mm to starboard from centre to provide minimum prop clearance.

Anyone else had a similar issue, I'm totally stumped outside of torque roll? Any help would be appreciated.

[Jesse J]

Have you blue printed the hull?
And what servo and rod are you using?

[Simmo]

Thanks for responding Jesse, servo is 25kg with a 3mm rod and basically straight from servo to rudder which I thought should be ample for a 980mm long hull. Not quite sure what you mean by "blue printed the hull''?

[Jesse J]

That prop size shouldn’t cause torque roll on that size boat; if set up properly.
What depth is the prop? Centerline of prop to keel?

Blue printing is the process of checking for and truing any imperfections in the flatness of the hull.
Take a metal straight edge and slide it across the hull parallel to the keel.
Some hulls have a hook (concave) near the transom, and if irregular from port to starboard, that can cause this behavior.

[jaike5]

I use a 1/4 scale servo, and a welding rod to the rudder, speed master hard ware. on my DF snipper. Your trying to keep a 18-20lb boat going strait , and stable in the corners when coming in at 70mph for oval racing. also I use a separate power source for the servo.

[fweasel]

Is the prop sharpened? Dull props can make the condition worse. I agree with Jesse, a 48mm doesn't sound like the diameter alone is causing torque roll, when that's the case, switching to a smaller 3 blade prop can help. Offsetting the drive line to the right of the keel center line is something that can help counteract torque roll. A hook (dip) in the hull surface just in front of the transom can cause odd ride attitude issues. Lay a straight edge along the bottom of the hull, front to back, and look for gaps between the hull and straight edge.

[Simmo]

Thanks guys for the input.
Prop is CNC and sharp and sits around 7mm above the keel ride pad.
I checked the hull for hook, both port and starboard are very similar to each other, about a 1mm concave over a distance of 300mm from the transom.
I have a 1/4 servo, I'll try that.
Would it make a difference if the rudder was centred and directly behind the prop instead of offset?

[RaceMechaniX]

I run a DF39 as a 6 cell mono and run 55-60mm three blade props and have no torque roll. It sounds like the CNC prop is causing the issue. Try a sharp and thinned Octura X447/3 or X450/3.
You can also try going to lower 1.4 pitch props instead of 1.6. This will also help.