Plastic speed boat off Ebay?

Cheap Chinese radio?

Set up details of the boat might help us make a guess.

Agreed! And of the rest, 90% are "Hardware/User Interface Conflicts"…… RTFM, guys – you don't have to admit it to anyone!
Brown-out is my best guess for this one too, Chas.

Bryan
Do you have any sort of luck except the lousy kind?

Dave M

Hi again Bryan, even fully charged batteries can cause this problem, if one or more cells go bad, or the charger is miss set or faulty. To eliminate the possibility you need to check them under load as I suggested.

I'm assuming your radio is modern 2.4 gig, so the chance of interference can be ruled out.

Are the tx batteries ok?. Not a likely cause, but worth checking.

Next to look at is loose wires, plugs and with your rotten luck, the switch. Followed by a check of the aerial, is it undamaged, and above the waterline.

A slim chance, some radio sets have a power/ range reducing setting.

Good luck.

Chas

Malcolm, I think the Etronix ESC has slow reverse as the default setting for loss of signal, but I could be wrong.

Bryan, fault finding is just a matter of strict methodology, follow a sequence, eleminating possibilities, and you'll get there.

Just for fun, do you have a non-digital one with which you can replace it? Indulge me and my irrational prejudices, huh?

DM

Bryan

I asked because some digital servos have the tendency to shudder even when they're supposed to be stopped. I wondered if you had an ordinary one which you could just plug in to try and compare. That said, it might be faulty and the one you've ordered OK. For £4 it's not a big deal anyway.

Speed controllers are a swine to program unless you have the appropriate programming card, when you just select the model type (aircraft, helicopter, car or boat) and it sets up reverse for you. The Fusion Hawk 30A ESC is a super little ESC and you can also get the card for not-a-lot – both from CMB. I can recommend it.

Dave M