Hi Dave B
For your Brushed Motor set up.
2 ESC's
In all cases you need to disconnect the red lead from one of the Esc's.
Pro's: You can control each motor separately if you use two channels on your Tx/Rx; The model will be able to turn in its own length; If one motor stops you can use the other motor to return to the side of the lake.
Con's: If you use a Y lead to connect both ESC's to one channel you will lose separate control and if the motors or props are not balanced one may run faster than the other; A dead motor will require recovery.
1 ESC
Pro's: Easy to set up;
Con's; the Esc will need to be rated at the max current for both motors; Similar problems with unbalanced motors or props.
Programable TX
Many systems offer mixing facilities allowing you to run say two motors on separate ESC's connected to two channels. You can then use one stick as a master channel and the other as a slave. This avoids using tank steering.
Mixing attachments
You can buy external attachments that will allow you to use one channel to control two ESC's and also link in the rudder control to reduce the inner prop speed on turns.
I have used all variants and all work but for a tug I prefer tank steering as this gives me absolute control in all circumstances.
For fast navy craft I prefer using a mixer on my Tx and I also use on my large passenger liners as the electronics manage the control far better than my ageing brain cells.
As an ex flyer I am not phased by using multiple Tx controls but accept that it is not for everyone.
Finally before anyone asks you can not connect two Brushless ESC's to one channel.
Hope this helps
Dave976

If you run 2 escs, either on separate channels mixed or on a y-harness, remember to pull the hot lead out of the connector for one esc. Most speed controls these days have a BEC, battery eliminator circuitry. You don’t need a separate battery for receiver power, and the esc supplies the receiver thru the red lead. If you have 2 supplying power to the receiver, you WILL smoke something. My first scale boat was a Krick Felix. I used a Hobbywing esc for the main drive, and an old 10 amp mini esc for the lights. I disabled the power wire on the mini, worked as advertised.

stotty,
I will most likely be using a Spektrum DX5C. The specs say that it has steering mix. I'll have to look into it to see if I need a specific receiver for that to work.
Thanks
Dave

Is your tx recent with the facility to mix channels etc? if so you can program the mixing function in the tx, no need for an exterior mixer!

Hi
Myself I prefer to use two ESC, that way I can have tank steering, so if one motor goes down I have the other to get back in on, if you do not like T/S then go for two ESC and a mixer, the mixer that I have in one of my boats is from scale warship (https://scalewarship.com) look under products for Forge at the end of the page is the mixer
Rudder mixer Mk2 cost £30.00

Hope that this is of some help

Fred