board sizes dont exactly mean will ya float or sink! the smaller the board the harder it is to paddle but the faster it will turn and ride on the waves (that is shape and wave dependant of course). a narrower board will give you more direct down the line speed but less stability, shorter boards give a faster turn but more sink into waves causing loss of speed(either way your gonna sacrifice something).

the dimensions you have given are really close..... u will barely notice the difference between the boards unless it is only real fine tuning that you're after.

what is you're aim out of getting a new board?

cheers jesse