He got out his equipment and materials and spread them out. There was no need to build a recorder, since there was one among the supplies. The rest wouldn't be unduly difficult. He established a working space and set systematically to work. The task he'd accepted was essentially simple. A submarine ear was to pick up underwater sounds. He had to modify a microphone and enclose it in a water-tight housing, with certain special features that would make it highly directional. The recorder would take the pick-up and register it on magnetic tape, while playing it for simultaneous listening. Then he had to assemble a machine for playing back the taped sounds under water. That required a unit for a submarine horn, to broadcast the amplified sound. It isn't difficult to make a sound under water. One can knock two stones together under the surface and a swimmer can hear it a mile or more away. But a horn to reproduce specific sounds is more difficult to build. It needs extra power. A sound-truck in a city, competing with all the traffic noises, will turn no more than fifteen watts of electricity into noise. But much more power would be needed to produce a similar volume under water. Terry modified the mike into a submarine ear--an _orejas de ellos_. Then he began to assemble an audio amplifier to build up the volume of the sounds already taped for re-use under the sea. He had the parts. It was mostly just finicky labor. He sat cross-legged in the sunshine, not far from the _Esperance's_ unusual winch. Nick came up from below and went aft. He spoke to Davis. Terry couldn't hear what was said, but Davis gave orders. The _Esperance_ heeled over; away, away over. The four crew-cuts adjusted the sheets for maximum effect of the sails on the new direction of motion. The yacht seemed to tear through the water like a racing boat. Terry had to rescue some of his smaller parts which started for the scuppers. He looked up. Deirdre said cheerfully, "Our radar picked up a boat that's probably _La Rubia_ on the way back to Manila. We don't want her to see us." Terry blinked. "Why?" "We're going to take a look at the spot where we think she catches her fish," said Deirdre. "It's strange enough that she catches so many, but what's even stranger is the kind of fish she catches at times." "How?" Deirdre shrugged. Then she said irrelevantly, "_La Rubia's_ skipper would like to have the only radar in the world, as you've reason to know, and he doesn't think of radars, except his own and possible competitors. But there are lots of others. We're probably a blip on somebody's radar-screen right now. In fact, we're supposed to be. So when my father got interested in _La Rubia_ and her--catches, he was able to have somebody notice where she goes every time she slips away from the fishing fleet. And so he was told. It was all quite unofficial, of course."