please help

[JTD]

I completed my first boat and started the tub tests. Not good.
The boat runs fine out of the water. The second the prop shaft hits the water the motor will give a little glitch. At half to full throttle the motor and servo will go nuts. This only happens when the stainless steel shaft hits the water.

I tried several motors and speed controls.
Radio is Futoba MJ
Shaft is stainless steel with brass stuffing tube and direct drive with brass u-joint.
The boat is a Dumas short stuff with Dumas hardware kit.

Please help?

[eddieh]

Jt, I have seen this once before, even with the motor supressed, my friend got really nasty glitching, one recommendation would be to try a graupner u-joint, the one with two carbon filled plastic ends, and a metal joint (about 8-10 bucks) my friend did this and the problem was solved, I wasn't involved with this board then, I would also be interested in any info regarding capacitors to use to eliminate this particular glitching, which remeins me go to the articles board and read the article regarding proper installation of capacitors,,,,, hope it helps dude, cheers eddie

[Don Wollard]

Not enough info.

What motor and controllers did you try? How many cells? What prop?

Do you have caps on your motor?

[JTD]

TRINITY P2K2
TRINITY D4 13T
TRINITY SPEED GEM RUBY 16T

IPC V6 ASSOCIATED
NOVAK SUPER ROOSTER

6 cells

And yes I do have caps on the motor.

[George Pfeifer]

JTD:
Have you solved your problem yet?

If not here is a test that you might try. Remove the prop and run the boat in the water. If the glitching disappears, then the thrust of the prop is causing movement in the drive train which is in turn causing some "electronic noise". Possible causes/solutions:
1. The thrust of the prop is pushing the armature towards the bow of the boat causing minor arching inside the motor can. Fix: put a thrust bearing between the motor bell and the U-Joint.
2. The thrust of the prop is causing movement of the motor in it's mount and something is shorting out. Fix: Isolate the motor from the motor mount, rubber spacer, nylon washers etc., or use a non-metallic motor mount, or tighten up the motor mount.
3. It's possible that the brass U-joint or drive dog is rubbing against the stuffing tube under load, causing noise, put a nylon washer at each end of the stuffing tube.

If removing the prop does not eliminate the problem, then I suspect that that something is grounding out. Are you using the Dumas Dog Bone U-joint, with the nylon dog bone between 2 brass connectors? If so try this, take a short piece of light gauge wire (speaker wire), solder one end to the stuffing box and the other end to the motor can. This might solve the problem.
Good luck;
George

[JTD]

George

I am using the Dumas U-joint all brass.


Thanks
Jason

[George Pfeifer]

Try a Dumas U-Joint with the Nylon Dog Bone if you have room to get it in there. This will electrically isolate the Motor from the drive shaft. Might work.

George

[T.S.Davis]

JTD,

Do you have BEC on your Novak? I have an old 410m5 I use and it glitched like mad. Went to a 9volt battery and got rid of the bec and it hasn't glitched since. Worth a shot.

Terry

[rcguy76]

like george said earlier...try the nylon dogbones...you might be getting some kind of grounding through the motor-to the drive shaft-into the water...the nylon dogbone will break that link

[T.S.Davis]

I just remembered. If you go to the Articles section on this site there is one written by Dick Crowe on this very subject. Lots of good ideas in there.

Terry