R/C Naval Combat

Was thinking of doing my wiring on the Indy this weekend.  So I looked up the swampy mag throttle diagram I have.  I had bought a 10amp spst switch for my power switch at Radioscam.  I notice on the swampy diagram it uses a dpdt.  Is there a specific reason for using a dpdt over a spst in terms of a power switch?

Because with the DPDT you kill all power, not just the positive or negative. You also wind up with an extra switch position that does nothing for you, but hey, not my issue

Realistically, killing just the positive or just the negative will achieve what you want in a warship. 10A ain't that much though, most ships run more than that between the motor(s) and the pump. Particularly if they're running an uprated pump motor. But even a regular pump motor is about 10A at 6V.

SPST switches only turn on and off,

DPDT switches can do on and off, where the both the on and off positions are connected to wires.  Turn this around and put Plus and Minus to the ON and OFF sides.  The switch that is not pushed supplies Minis to it's side.  The switch that is pushed supplies Plus to it's side.

You can do the same circuit with SPST switches, You just need to use four of them instead of two DPDT switches.