Cable raley vs wake raley
 

I've just learnt to raley (haven't perfected it but landing them at least lol) and was wondering, is the principle the same when doing a raley over the wake? ie need to dig backwards at the wake?

Also has any1 done a raley on the water not using the wake say off to the side of the boat or something or is it pretty much impossible cos of not enough line tension?

I learned my boat raley the same way. I perfected my air raley, even learning to land krypt, so I developed a lot of air awareness. Taking it to boat is definitely different, and most of it's mental. Take a hard, BUT STILL PROGRESSIVE, cut all the way through the wake and let your legs extend out like a pendulum. The rest of it feels like it does on a cable, you'll know how and when to pull back in. My biggest problem is that I tend to "stargaze" really bad due to developing an uneven weight distribution balance from the air raley.

On your second question, very few people have done the same type of air tricks on boats, but I've heard Mark Kenny used to ride comps by doing wake to wake tricks, air tircks in the flats, and then comeback and do another wake to wake trick. The only video evidence i've found for this is here:

http://youtu.be/2YICRYCg5W4

It's at about 3:15 - 3:25

Good luck on the raley