ok, David shamed me into finding some time to do more testing.
conclusion 1; I dont like mode 4 on the esc. its too similar to what I had before, great big turning circles.
conclusion 2; I do like mode 3. Mode 3 is good. I can get a 3 meter 360 under full power, and I can steer to berth pretty good on the rudders alone.
conclusion 3 There is something wrong somewhere....
with the rudder on full right, the throttle works the motors, but makes the boat go backwards, regardless of whether I'm pushing forward or back.
This does NOT happen on left rudder, that works fine.
I've checked the props, they are on reversed, I shall change them over when I've got time
The motors dont start together, there is a slight lag on the right hand motor, but only a fraction of a second. But I cant see either of them being the culprit, so help please......