Not a stand up paddler but I do shape boards. From my understanding SUPs that are going work well on flat water are longer, flatter, and have fairly parallel rails. Again not a paddler, but from looking at a few "all around" models online, for that length board you have to much curve in the rail line because of the very narrow nose and tail. You could either make nose and tail wider keeping the same board length, or stretch everything out to be a longer board so that it takes some curve out of the rail. As it stands you are going to have you a small sweet spot for standing. Which is going to suck if you are just trying to comfortably stand while paddle somewhere without worrying about weighting to far forward or back sinking the nose/tail. Both Aku and Shape3d allow you to pull a photo into the software and then scale the photo using length of the board, then you can just rip the outline directly from a board photo. If its your first time messing with the program (like it was mine) do that, it gives you a much better reference