Hiya
Good gps's are the garmin and magellan range. I find the garmin range to be very user friendly. Have a look at:
http://www.gpsw.co.uk/cats/cl3_23.html (just did a quick search, sure you'll get better prices!!) An entry level gps costs about 60quid.
All you need is a basic unit. No need for maps, as this only push's the price up. A simple straightforward gps is all that you need!!
I've got a Garmin GPS72 on my 21' rib. I use it to find spots with, to run home in the fog/mist or dark from 40nm into the sea, through narrow ports with rocks on either side, pass extensive kelp beds, etc. It also has a built in tide time-table as well as a sunrise and sunset time chart, plus handy things like a trip meter, speed you're traveling, current time, etc. No fancy maps on it!!
Word of caution: buy rechargable batteries, as a gps unit eats batteries!!! I have mine hooked up to my boats batteries, and still carry a spare set of batteries for the gps.
Regards
miles
