1) when you turn on telemetry, the receiver is now transmitting 50% of the time, so it is now the largest rf emitter inside the submarine. forget about capacitors on a brushless motor, this makes that look like the radar outline of a duck vs a b52
2) the "antenna" wire lengths needed to carry that signal out to the servos (as interference) is only 6".... about the same length as a servo wire.... in the 75mhz and 40mhz world, that length needs to be over a meter.
3) the antennas that all the systems ship with are monopole. they aren't grounded in any way (dipole), so they are less efficient and generate more noise.
it seems to vary from submarine to submarine. my skipjack and delta are completely un-affected, while my blueback suffers so badly that the servos actually twitch about an 1/8th of an inch.
in order to even make my blueback work, i had to wrap the servo wires around ferrite rings to kill the interference. something like this: http://www.ebay.com/itm/301198587261?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
i put one of those on every servo wire (including esc)
those are the exact ones i bought, and they dropped the interference to a point where the sub can now work. I assume that if you have room to install a proper dipole antenna, that would reduce the interference as well.