Speedrug, see if there is somebody at your dock with a hand held GPS that you can borrow. Or purchase on now and you will have it for a back up in the future when your buddy gets a full sized one.
You can pick up a hand held for probably about $100. or so.
If that is not an option, I have a hand held that I will lend you if you want to pick it up. I will be at Shark River over the weekend and in Hamilton (Mercer Co) during the week. My hand held is only the GPS, no chart function, but you can put the numbers in it and it will direct you right to your spot.