Drew Cutter wrote:
Has their been any studies on how much more energy you use on different
water conditions ?

Not that I know of. All I can tell you from experience is that your
effort level can go up exponentially in rough water, particularly if
you're uncomfortable or you have to do a rescue in it (self or assisted).

I want to take some Greenland paddle skills classes.

Good idea!

Brian Nystrom wrote:
Drew Cutter wrote:
I've been looking at the Great lake kayak club. They give rating on
skill and difficulty. How does one build up their endurance for
paddling the great lakes ? Especially when the waters get rough and
windy .

Paddle a lot. Seriously, it's he best training for paddling. If you
haven't done any skills training (strokes, bracing, rolling, rescues),
you should do so and get a solid foundation before you start paddling
big water.