I have started to build the mounting points for the deck extension framework, but was wondering what thickness of ply everyone has used for their decking, both on the floors, and elevated. I am currently planning on using 1/2" for the floor, where there is a rib approx every 18"-20". It will be attached to the ribs with 1" stainless lathe screws (similar to a pan head screw) every 12" for torsional rigidity, however it is the flex in between the ribs I am slightly concerned with. The elevated front and rear decks will only be extended from the existing front deck 1' and from the rear seat 4-5". I would like to use the 1/2 on the elevated decks to save the weight over 3/4" ply and from the best I can tell, the small amount of 2x2 and 2x3's I will use to frame and brace will be less than what the 3/4" will weigh. (I am figuring approx 8' of 2x2 and somewhere around 6' of 2x3 will be used). This is a 1652 with a 25hp Merc 2 stroke that I am hoping to hit mid to high 20's in so weight is an issue, and aluminum is simply out of the question.