The oldest known surfboard made in Texas doesn’t float. Unlike modern boards, this one is hollow and finless. At nearly twelve feet long, constructed of vertical strips of magnolia and pine, it looks more like an oversized ceiling fan blade than a piece of sports equipment. When R.W. Ellisor, a Galveston County teenager, built this board in 1946, he added layers of muslin and then shellac to ensure it would be waterproof. Today, the surfboard stands propped up against a brick wall inside the new Texas Surf Museum in Galveston. Much of the finish has worn away, leaving the board’s deck half-bare and its internal structure exposed. It’s one of hundreds of artifacts on display at the museum, which is set to open February 20…