For sure the range problem is the location of the antena in the hull. Us a piece of airlpane nyrod and thread the antena wire up into it. Use a couple of 8-32 nuts to thread on to the nyrod and clamp through the deck of the boat or radio box if you have one.

As for the batteries, keep the dry cells. Just remember to replace them after every 3-4 hours of use. I switched all my race boats to dry cells after I blew a days racing with dead nicads left on all night before. If I had dry cells then, all I needed to do was changed the batteries for fresh ones. Having fresh batteries is a cost of running for the weekend and that's not bad.