One additional tip, don't deck it until you have the frame floating, it's much easier to launch that way.
Brings back memories.
I finished the entire deck on dry land. My little 35hp tractor was just able to lift the deck and ease it down close to the water. Then my No2 son floated the barrels in place between the 2x12 joists. When they were all in place, I eased the deck down on the barrels. Wish I had got a picture of my little tractor hoisting up that deck!
