Buying Advice......

Hi,

I am very new to GPS systems and despite having done several evenings research on them, I still have no idea what will suit me best.

I am a keen (responsible) motorbike 'green laner'. I am planning a trip to the Isle of Man next year and don't want to navigate with paper maps. So I was thinking of buying a second hand (because it might get rough treatment) handheld GPS that I can mount on the handlebars.

It will need to have:
1:50000 mapping (like Landranger showing contours etc.).
The ability to plan about 50ish different routes (each one with several way-points) which can be done before the trip on my computer.
The individual planned routes should be able to be called up in any order.
Be able to be powered from the bike 12V supply.
Have a moving map (I think they all do this?).
It would be good if it could track where I have been.

Are the above something that all of the GPS units do or do I need to look for a specific model?

Many Thanks, Rob