Re: Gps advise
I almost went the handheld route because of two boats. Didn't find a handheld unit that had acceptable Chessie mapping without shelling out 100+ bucks extra for maps. A handheld of decent screen size and features, combined with the need to download at cost more charts, got more expensive than a chartplotter/fishfinder combo.
I'd ditch the finder you have, sell it on ebay (be gone in 1 day) and get a combo unit that mounts (e.g., Garmin 400 or 500 series). They have acceptable coastal and inland water maps and the upgrade you can download is just to kick it up a notch.
I'd bet after you do the math that this is the best use of time and money.
Lowrance Elite Gold 4 or something like that is a nice option. Has their gold series charts preloaded.