hi all im wanting some infomation on receivers for ep boats are there any special receivers i need for them.
i have a DX3S transmitter and am wandering what receivers i can use.
i have 2 gas boats and am using the mr200 marine receiver in them but can i use this receiver in electric boats?

You can, In theory use any reciever you please.
However, if the reciever is close to the electrical driveline (battery, esc, motor) it will pick up some noise from here.
With AM and FM-PPM, that can cause radio interferences, even on the more expensive brands.
I experienced it, Im running a Futaba 9C.
With FM-PCM (2,4 ghz included, its the same modulation, just different frequency) you are practically immune to this noise.

To answer your question that rx is fine for electric boats, the dual antennae helps to eliminated signal loss in a marine environment that can happen with all 2.4 systems, never experienced it but the signal can be reflected off the water, also the signal doesn't penetrate water so make sure you antennae are above the water line.
Remember also that not all Spektrum receivers will not work with all Spektrum systems, I always use the marine rx so off the top of my head I can't remember what works with what, Look for the surface and marine logos on the rx and you are ok.
I'm sure you already know those rx are water resistant.