Controls problem
Thank you for your replies!
Low battery is not impossible; but it powers the motors fine direct, receiver lights come on, ESC lights come on, and the phone connects to the receiver fine via WiFi, so I assume it's OK.
Peter - I will pop along to Bury, probably today, as it's a lovely Sunday morning. Thank you.
RNinMunich - I don't have a compatible TX but will look into that at some point.
I did consider the 1:350 version, but read that the dies were very old now, and that the Academy 1:400 was more recent and far more accurate.
I'll show some pictures of the hull layout later. it was quite a struggle, and I've gone to quite a bit of effort to keep it balanced, with a heavy water pump towards the front to make it go 'down by the bow' (but not sink). Yes, quite ambitious. The hardest part was that the two outer props are incredibly close to the hull, so that only very small motors will fit. I didn't want to go for any sort of flexible coupling as I thought that would lose too much power, and larger motors probably wouldn't fit anyway.
I don't really mind if it's slow and hard to manoevre, as that would be realistic. if it doesn't work I may rip the motors out and just pit one big one in the middle and steer by rudder.