[badlander]

You'll be okay for a couple of hours maybe,thats with a hood,gloves, socks etc but there really is no substitute for a 5mm two piece open cell diving suit.I was confident that i'd be warm as toast but it really is surpring how much heat you loose when remaining pretty still in the water is the name of the game.With a dive suit you simply won't get cold in the summer and thats a good thing when you're staying in for 6+ hours.
I made do with a Salomon 4-3 for a couple of years and it's probably gonna be fine,but for the price you can pick up a dive suit,it'll be well worth your while.