I have recently constructed a rotating radar mast for my 1:48 scale paddle tug "Forceful" I have used a geared 6 volt 60 RPM motor which gives a realistic scale rotational speed. It is a little noisy but only when close up. it is driven by a direct shaft running up the centre of the mast not prototypical but gives a pleasing effect. I may rebuild this at a latter date to eliminate the noise
It may be a transmitter/receiver problem or it may be in your drive setup that rears its ugly head once your on the water and your motor is under load. I had a similar problem with a twin motor setup which was fine out of the water but after 10 mins in the water I would lose drive to one or both props or one would slow down and just go round in circles (very embarrassing). I had no problem with radio setup so it had to be in the drive chain. I ended up changing both motors for ones with more armature poles, higher torque output and a different gear ratio. It also highlighted a problem with my first choice of battery which quite frankly were pants and used to produce similar symptoms as you describe. I now use Lipo power packs, they do have disadvantages but you can not knock the power to weight ratio. The main problem I was having appeared to be down to the 3 pole motors that were fine until they were under load, this caused the motors to overheat which in turn increases the current drain on the battery's, the net result is the motor starts to arch across the commutator and effectively becomes a dead short which in turn shuts down your ESC's or drains your battery's very quickly. As you probably know if this was to happen with Lipo's there would be no need for a smoke generator! Of course this only applies to brushed motors if you are using a brush-less motor then it will probably not help you.
[Score: 5/10] 39"/6000g Forcefull Belt to a 2xMFA970D161LN Powered by LiPoly (11.1v) 4Amp/h Batteries Controlled Through action elelectronis dual 10A ESC/mixer (5Amps) ESC - Comments: This boat is still under constrution (Ive still to finish "Shell Pioneer") so a lot of the above is only guess work however a bench test at full throttle, with sound generator, amplifier and smoke generator operational it drawing less than 3A. The majority of this was the smoke generator with the drives only drawing 0.25A (under no load) so if these figures do not increase too much once in the water i should get a much longer running time from my 2 lipo packs
I am so pleased to see this blog as I am also in the midst of building my own "forcefull". Your build is much further advanced than mine so hopefully I may be able to pick your brain in future about the many problems that I am bound to encounter. Your drive system looks much like mine apart from I am using 2 x 540's low noise motors with built in 16:1 gearbox and the final drive being belt drive reduction giving me a maximum no load rpm of 230 on the paddle rims. I am using an action Electronics dual mixer & ESC's in tank steer mode for speed control. I don't know how it will handle exactly in this mode but I do have the option of a conventional mixer mode with a rudder servo. At the moment my paddles are not feathering, this is just for getting in the water quicker and will be replaced in time when I can access to a lathe to make the ecentrics
[Score: 5/10] 31" Shell Pioneer Twin Propellors (4 Blade 35mm) Direct Drive to a 2x MFA940051LN (4 Blade) Powered by LiPoly (7.4v) 4Amp/h Batteries Controlled Through 3xViper 15A (5Amps) ESC - Comments: This is my first working RC build but here goes. A bit vauqe about the fiqures because we are still on the slipway. It is scratch built from the Phil Thomas drawing "Shell Pioneer" Twin prop with Kort nozzle steering, bow thruster, working fire monitors and lights. Throtle & steering control via Action Electronics P40E mixer. 2x 2S25C4000mA lipoly's. 6 Ch radio (4 used). draws around 4.5A hope to get 30min run time minimum. Third ESC for bow thruster.