Ft desoto is at the south end of the bay just outside the Skyway (by boat). I am there frequently windsurfing. I do not know of anyplace to launch a cat from directly to the gulf. You may be able to launch from the boat ramp, but it will be a tricky sail out the narrow channel to the gulf due to VERY shallow water around there. You may be able to launch from the very beginning of Tierra Verde causeway. From there it's a short sail under the Skyway and to the park.