‘Having a kayak and a paddle is all you need to get going’ some say. I totally disagree! Not that I can't go sailing with only those two items. But because I like trips lasting longer than 15 min. I have bought me some clothing, safety equipment and will be bringing provisions along.
Clothing: Rowing jacket, long johns, a pair of neoprene shoes, hat, sunglasses and neoprene gloves. All this can be combined after comfort and supplemented with skiing underwear and the like.
Safety equipment: Sprayhood, Paddle Float, a towline, safety line to the paddle and a mobile phone in a watertight cover.
Provisions: What ever I think I will be needing, but as a min. always water and some type of energy bar.
One thing more: The kayak is a expedition HV model and designed to be loaded with gear, so for day trips It will probably behave better in the water with some ballast. I need to find some sandbags or the like if that proves true.