Kayaking Resource

I mean when you do it right, like the sprint kayak competitors. Not like taking a leisurely paddle on the river.

I am a rower but I cannot afford my own shell to practice in by myself. I know rowing works more muscles, but would kayaking work muscles that matter for rowing or is it all just arms?

I am planning on kayaking around the pictured rocks in the beginning of August, but I have no idea of what to wear since it will probably be chilly. Any suggestions?
Any Kayaking fans out there?? The water will be about 54 degrees (f) and the air temp will probably be around 70 degrees (f).