Two experimental SESs (the SES-100A and 100B), both of around 100 tons, with 80 ft (24 m) length and 40 ft (12 m) beams, were developed for the US Military in the 1960s and 70s. They both attained speeds in excess of the program goal of 80 knots (150 km/h). The SES 100B, was built by Bell Aerospace (Textron Corporation) at the NASA Michoud Assembly Facility. Driven by 2 semi-submerged, supercavitating controllable, reversible propellers, achieved speeds in excess of 96 knots (approximately 110 mph) in the Gulf outside St. Andrews Bay in Panama City, Florida.