Not used that sort of thing on the RIB, but I have whilst walking/climbing.
Not sure I would choose a Cap light though as
a. need to have a cap on your head
b. I think they use CR2032 cells which are not easy to buy (button cells).
The one I have for walking uses 4 AA batteries and is a Head torch bought in an outdoor shop.
They are (or were) available with a red light (not much good for maps), and most are waterproof enough.
Head torches 1
Head Torches 2
Tim