Using my Tx in the configuration described in my previous post I found sea trials very successful.
On the right stick (ail. and elev.) I have both motors running forward and reverse and left and right rudder.
On the left stick (rudder) I can control either motor separately with proportional rudder which allows the boat to turn in its own length.
Quite a pleasing evening on the pond.
Steve

well .. I do not use practically the rudder, because in this configuration on my model is practically ineffective, even though is still working on can 4 - Rudder.
Due to difficulties in setting internal mixer of the transmitter for 2 motors, I chose an external V-tail mixer;
it struck me as easier to adjust.I had always had constant problems with the engines, it turned out at the end that it was defective ESC on one of the two engines.I had to buy two new esc, but from a different manufacturer. The system then worked ok, so I did not need to change the settings.

Hi Folks
Thank you all for your advice.
I think I may have found the solution using my Tx.
Speaking to a fellow club member at the pond today I noticed that he had the same Tx and also flew model aircraft.
He advised activating the V-Tail under the Wingtailmix in the Setup menu and the Rudder to Aileron in the Mix in the Adjust menu.
I now have motors and rudder on one stick, so I have the basics.
I will be fine tuning at the sea trials on Thursday evening so I will let you the outcome.

Hi Tomarack - yes I suggested that option of connecting a mixer in my first post on 28th July and I think it's a good one as a human is involved in the mixing scheme rather than some pre-determined mathematics which may not suit everyone or may not cope with unforseen conditions. But it does cost a spare channel - so it's down to individual preference

I have on my model Lulonga quarterwheeler control the direction by changing the speed of individual motors. I use an external V-tail mixer and mix Throttle (can 3) and ailerons (CAN 1). Without problems, one control stick. I think it's more convenient, than mix rudder and throttle.(Rx = HK6A 6 can.) >
if I thr. stick in neutral and lean it to the left or right, the motors have a reverse operation, and the model turns nearly in one place. I use sound mixer module connecting before steam sound unit , on the water just as big a difference can not be heard. You can of course use connecting the sound module with Y cable. This is in my sailing model boat with "iron topsail". I switch it over relay, thus imitating the sound of starting.
Tom

Cormorant - I'm not in my own back yard here, but v-tail mixers for elevons mix the elevator channel with the aileron channel. So I assume you would need to use those same (aircraft) sticks on the TX - unless like Haverlock you have a Taranis! This puts control solely on the RH stick (assuming a mode 2 TX). Marine modellers like to have the throttle on the left stick. I wouldn't be happy with the throttle elsewhere than on the LH stick from the point of view of failsafe. Aircraft have so much space and height around them that in tempoary loss of signal the safest option is to keep flying as you were so the non-throttle channels stay at their last setting until signal is re-established - so if you are using an aircraft non-throttle channel for your boat-throttle in order to take advantage of the TX's inbuilt mixing, then in the event of signal loss you may find yourself heading out of the lake and into the carpark. The (aircraft) throttle channel differs in that you can usually program it to take up a user defined position in event of signal loss.

your rudder needs to be fed as does your second ESC so you need a "y" lead to connect both your ESC and your rudder servo to the same output.

if you want to have control on one stick you could use a elevon mix ( elevator/aileron ( see page 12 of instructions)) then you could leave your rudder on its own channel.

Thanks for that, it seems a mixer is the best way forward.
Couple of points:-
1.I assume I can use one stick for this operation. The rudder and elevator are on different sticks - rudder and throttle are on the same.
2. Not having used a mixer before, where does the Y lead fit in?

If you wish to use a Spektrum DX6i then I can only offer the idea to use the "v tail " mix and connect your 2 ESCs to receiver outputs for rudder and elevator.

You can take a "y" lead connection to the rudder servo.

The reason I said the taranis is that its a completely open ended TX so you can mix anything with anything and have logical switches as well.

Hello Alan
Permission to join this forum?
Octman and I are old school friends and have been modelling on and off for 50 years.
He and I have been trying, in vain so far, to use the mixer on my Spektrum DX6i.
I am building an Aeronaut Pilot Boat which has twin brushed motors, which I would like to control with one stick and use the motors to assist turning at low speeds.
The Spektrum instructions, which leave much to be desired and the many youtube videos, deal solely with aircraft, so I am struggling.
Unless there is anyone out there that has programmed a DX6ifor this purpose, the description of your rudder mixer seems to be the ideal solution?

Agreed! - if you have a number of models requiring mixing, the additional cost of a Taranis over a more humble TX (mixer per model) will soon pay for itself as you can implement free mixers in all of them. But not everyone can cope with programming high end TXs. For some I know, just binding a receiver is an ordeal - yet these same guys can tackle the most intricate detailing on their models whereas I use Flora tubs for the cabins and toilet rolls for the funnels! We're all wired up differently but the great joy of a club is there is usually someone who can help you out with any skills you are lacking.

I was being serious, using a modern Tx Rx setup removes the need for mixers in the model. With free mixing on the Tx you have a much more flexable situation than a dedicated unit in the model.

and whilst blindfolded shout steering instructions to a one-armed helper operating the TX . . . . . .

However we can simplify the whole thing

1) buy a taranis RC Tx and Rx

2) feed each ESC from its own channel

3) set up the mixing on the Tx

4) set the motor sounder on its own channel

now you can have a mixer for throttle/rudder and have independent control of motor sounds

^5 have fun on this forum

Your honesty does you credit - you sir, are a true gentleman - so much so I've heard, that you'd never dream of wiping your nose on the tablecloth if you could possibly reach the curtains!

Hey we haven't had a pissing contest in a while, on reflection I think I am wrong anyhow!!!
How's that for honesty?

phew, that's a relief, I was anxious not to start a pissing contest! At the outset, with 100% mixing of rudder into throttle demand I found that as speed increased my boat accelerated into the turns which was undesirable. At speed, rudder authority is usually enough to steer adequately, it's just low speed where manoeuvrability can be a problem - particularly if a single rudder between two props is used which doesn't have direct propwash passing over it. So I made the proportion of rudder mix variable 0 to 100% (ie as you say, rudder can be set to merely be a modifier) and found that setting 50/60% was a good compromise for good steering behaviour at speed* - however, when slow or stopped, turning is not so vigorous as with 100% mix. Thus I went on to develop what I call "dynamic mixing" - this gradually reduces the mixing from 100% when stationary to 0% at some level set by the user (zero mix occurs from approx 30% full speed to 100% full speed) - this allows you to have your cake and eat it.

If you are prepared to sacrifice a spare proportional channel you can get the same effect by assigning the rudder input of (any) mixer to that channel - L-R on the left stick is a good choice. Now the boat responds to throttle with the L-R stick input as a modifier which can be as gentle or fierce as you like to suit the situation you find yourself in.

*50% suits my beamy tug - long thin destroyers with woefully inadequate scale rudders may need far more

laughs if your mixer increases throttle with rudder input then I agree what you said would be true!!!

its an interesting proposition so the feed to each ESC. is an integration of both signals. How do you handle low speed turns? I expect gentle inputs.

Most commercial mixers use throttle as main input and rudder as a modifier.

Oh dear, as a humble seaman I must defer to a Captain's authority and wealth of experience - maybe we are talking about two fundamentally different systems? As I make my own mixers I don't have a great deal of experience of using other offerings in the market place - so I'll describe how my mixer works and will welcome any comments - maybe we are both right!

The mixer produces two speed demand outputs to the ESCs where the throttle input adjusts them in unison and the rudder input adjusts them differentially (ie increases the motor speed on the outside of the turn and reduces the motor speed on the inside of the turn in equal and opposite amounts. Thus to spin on the spot with my mixer the throttle is set at zero and the rudder is put hard over so one ESC sees 0%(throttle) 100%(rudder) = 100% speed and the other sees 0%(throttle)-100%(rudder) = -100% speed ie the motors are at full speed ahead and astern. So if the sound unit is connected to the throttle input it will be making a tickover sound - the motors having achieved full drive from the rudder input alone.

I'm aware that there are some variations in implementation - like only slowing the motor on the inside of the turn and only mixing in a proportion of the rudder input.

Check out my youtube video from 2009 where the boat is turning eitherr way on rudder input alone

If the sound module is connected to the throttle before the mixer then the sound you get would be a full throttle sound in the situation you outline since the throttle is at full but the rudder input is causing the one forwards one back outputs to the motors. With little or no throttle input using the rudder input will have little effect on motor speed.

Hi Octman - a bit late now (and I've only just discovered this forum!) but if you'd used my mixer it has a "throttle out" signal which is the faster (fwd or rev) of the two outputs that drive the ESCs. in your case the best option is to connect between the RX and mixer throttle input otherwise you'd get different sound effects when turning in each direction. However this is still a compromise and you will find the paradox that when spinning on the spot the props will be full ahead and full astern, the water will be boiling but the engine sound will be a gentle tickover! My processed "throttle out" signal avoids this problem. (Incidently, I'm the designer of the Technobots sound units and prior to designing the mixer I addressed this problem in their programmable sound unit by providing two throttle inputs which you connect to the two ESC inputs - another way to skin the same cat!)

Those of you for whom it is not too late can check out my rudder mixer on my website:-

http://www.forge-electronics.co.uk/index.php/boats/rudder-mixer

where you can download the instructions. in addition to the (true) "throttle out" feature, the mix is continuously variable from 0 to 100% and there is a unique "dynamic mixing" option.

They are available from www.scalewarship.com

Thanks, that's basically what I said in my original posting, so thanks for the confirmation. I think the fitting betweem Rx and mixer is probably the one I will use.

You could fit it twixt the Rx and the mixer since its a "pass though" module and bases its output on the throttle setting directly from throttle output is place to fit.

Your mixer will mod the signal ( that's what its supposed to do) so you need throttle before this mod.

if you fit twixt mixer and one motor your output will reflect that motor only.

Either will work so you pick! Which is simpler physically for you to do .