Removing the gearing was always the intention, the motor would need to run at whatever rpm the motor is design for, although that might still mean that it still not fast enough, 1.3 kilograms !, with this boat i would probably be near to having the waterline flush with the deck at anything over 100g, hopefully find a powerpack that goes to 6v and not be any bigger than AAA batteries would be ideal, scale speed although would be nice, but flying like a bat out of hell is not practical, lasting 5-10 minutes would be preferable.
The brass prop's I have are prop shops M2 threaded about 10mm dia, I think, I was not intending to use the kit ones as they are totally impractical and would not push the water round a tee cup nevermind a bath.
From the description of the servo's i assume you mean futaba type F128's, would do, give a good turn of speed, so all I would have to do is remove the gearing, make sure the motors are free running, line up with shafts plug into receiver, attach battery pack and off we go, using servo's as forward and reverse (tank style operation) to steer, if weight too much could mini (not micro) servo's do?.
There's a new thread for mini tugs just started, would this applied to that as well?
Warspite