If the portable mast revolutionized airship operations over land, experiments started by the Navy in 1938-39, largely under the direction of Lt. C. S. Rounds, promise to be just as important in over-water operations. These showed that the airship could pick up ballast from the ocean, could get fuel from a passing ship, could change crews at sea. Ballast is important to a vehicle which growing continuously lighter as it uses up fuel, must still be kept in equilibrium. Transoceanic Zeppelins, using hydrogen, had to fly high enough to “blow off” the surplus gas once or twice during a trip to compensate for the ship growing lighter. But hydrogen was cheap, and could be manufactured as needed. American ships could not afford to waste helium, which was a natural resource. Army and Navy engineers had worked on this, and equipment developed for the Akron and Macon to condense the gases from the burned fuel was able to recover more than 100 pounds of water ballast for every 100 pounds of fuel used. The blimps didn’t use these since they ordinarily would not be out for more than a day at a time, still a ready source of ballast would make it unnecessary to valve helium on long flights. Ironically enough a whole ocean full of ballast lay below seagoing airships, but no practical method had been devised to take the sea water aboard until the Navy tackled the problem in 1938. That problem may be visualized in the obvious difficulty of maintaining physical contact between an airship and a surface ship. The two move in different media, one influenced mostly by the waves, the other mostly by the wind. The surface ship is moving up and down, the airship subject to gusts which might break the contact or thrust it violently against the masts or superstructure of the surface ship. Servicing has been done under favorable circumstances, but could not be relied on as standard procedure. The solution reached was this. The pilot swings his ship down to within 100 or 150 feet of the water, lowers a hose with a small bronze scoop, not much wider than the hose, so as to lessen the drag. Twenty-five feet up from the scoop is a streamlined cylinder, blimp shaped, carrying a small electric pump. This cylinder, nicknamed the “fish”, has tail fins to keep it from spinning, and skims along the surface or jumps out like a porpoise, but the scoop is far enough behind and heavy enough to trail easily beneath the surface, stays directly in the ship’s wake, continues without interruption to pick up ballast for the airship above. The whole gear weighs slightly more than 100 pounds, can pick up water at cruising speed, can function in rough water or smooth. The Navy J-4, chiefly used in these experiments, normally consumes 500 pounds of fuel in five hours of flying at cruising speed. It was able to pick up that much water ballast in seven minutes.