hi there;
May I just take a moment of your time so I can make sure I have this clear in my mind your control set up?
So, what you are basically doing is you have 3 x speed controllers which control x 4 motors? 2 outboard motors, I take it, are ganged together on 1 speed controller & the 2 centre motors are on independent controllers?
These 2 inboard motors are the only ones being mixed with the rudder function?
So, these are controlled by 2 channels on your handset?
You have a 3rd throttle channel, which controls your outboard motors - and you have a 4th switching channel which switches this channel in and out - in actual fact you are using 5 channels to control the movement of the boat.
What Riggers is trying to explain to you is; with the ACTion P94, you would be able to control 2 pairs of motors - in other words 4 motors. This is because there are several facilities on the P94 and 1 of them is to add an extra speed controller - so, you would still have the mix of the 2 outboard motors or inboard (whichever you prefer) and the 3rd speed controller would not be affected by the mix, it would just respond to the throttle settings either ahead or astern.
The other function is that you can adjust up to 50% of the mix between rudder and throttle. This would eliminate the harshness of the mix. Now, the next piece which I shall mention is my own experience, from when I built a model of HMS Ajax.
HMS Ajax is also controlled similar to the way you are doing it, only instead of the Futaba 2.4 6EX mine is the old 40 mg version – same sort of mix facilities on it; and by only using your inboard props mixing you are going to find it difficult to turn the vessel. What I found was, you have to have the motors ‘ganged together’ in pairs. In other words one speed controller controlling the motors on portside and one controlling starboard side.
You will possibly find, that having 1 set of props sitting idle, whilst the other 2 are trying to do the work will be more of a hindrance than a help.
The last thing I would err caution on is slowing down rudder movement; the model you are building is going to be a fair weight when you have completed it. Natural momentum of the vessel going through the water, with its weight – it is going to take something to stop/ turn it. You will therefore require all the power you need and all the movement of your rudder as quickly as possible.
The model I made of HMS Leeds Castle at 1:48 Scale will be something in the region of a similar weight to yours – she carries 3 x 12 volt x 12 amp wheelchair type batteries. When she is under way, believe me – she takes some stopping ask Riggers to show you the photograph of the ‘chunk’ out of the side of lake and the state of the bow of the Leeds Castle.
Food for thought; and I can appreciate where you are coming from – because like me – you like to experiment with your radio gear and so forth. Best of luck.