“The gizzy between the sponsons is a spoiler, meant to prevent stuffing the bow if the boat flies a bit and comes down nose-first. It went away in 1958 after Ron Jones suggested they could achieve needed anti-stuffing result with a little aft weight adjustment. Ted still wasn’t sure, so they did Ron’s suggested balance adjustment but with a pair of mini-spoilers inboard of the sponsons, and when Ron’s idea worked out those were removed. Here’s the 1958 Bardahl with the temporary spoilers”.