FM Dual Conversion 'conversion' questions

A friend of mine recently bought a Futaba 4 channel FM dual-conversion radio to upgrade his boat. I’ve heard dual conversion is a good way to go, since it cuts down on a lot of interference. He also mentioned that the antenna for the dual conversion receiver is much longer than a standard AM one. Does anyone know if all of that extra length is necessary for an RC sailboat application? I was thinking of upgrading, and right now I have my antenna under the deck ran through a straw… this works ok, because I only have maybe 4 inches of excess antenna. However, I can imagine with the extra length of the FM dual conversion receiver, this might be a problem.

Does anyone have any experience with this? Up to this point I’ve been using basic 2-channel entry level radios.

Seawind #25, #28
CR-914 #1186