A self-retracting cord is a great idea! Seems we've had to deal with those coiled mic cords forever, while all the other technology around us has improved. I suppose a boat is a harsh environment for something like the self-retracting power cords found on some vacuum cleaners. And it wouldn't fit neatly into the standard size dash unit. Still, I'd be interested if some manufacturer offered that option.
I've tried wireless mics and the delay is a bit of an issue, although once you can get used to it with practice.