When they arrived at the docks, Tom gathered the men in a loading shed. He showed them his drawings and explained how his "sonar-blinding" setup would operate. "Don't let the diagrams fool you. The basic idea is very simple. We absorb all sonar impulses that hit the ship and transmit them out the opposite side of the hull, instead of letting a ping bounce back and show up on the sonarscope of any hostile sub on the lookout for us." Most of the job, he went on, would be tedious detail work. It would consist of attaching hundreds of mikes and speakers all over the hull to pick up and transmit the sonar pulses. The mikes would be receiving transducers and the speakers would be transmitting transducers. "The leads from them," Tom ended, "will be centralized in a single electronic control unit inside the ship. I'll handle that part of it." "Great idea, Tom!" Arv Hanson said admiringly. "But what a job it'll be rigging those transducers," put in one of the technicians. Tom nodded wryly. "You're right, Danny. If this experiment works out, though, I think I can lick that problem on future installations." The young inventor explained that he hoped to find a way to mold the transducers into a continuous plastic sheet. This could be applied to the hull of a submarine in a single operation. "But this time we'll have to do it the hard way," Tom added with an apologetic grin. A jetmarine was hoisted into drydock and the work crew swarmed over it, rigging the transducers. Would his experiment succeed? Tom wondered. Hopefully, he set to work assembling the electronic control unit. Bud helped the men on the hull for a while, then descended through the hatch to see how Tom was progressing. [Illustration: _Would his experiment succeed? Tom wondered_] "I'd go gaga trying to keep track of those circuits," Bud said, as he watched Tom installing the delicate transistors and other components with an electric soldering gun. The young inventor grinned. "It'll be simple enough when the control unit's all put together," he replied. "Just a single on-off switch and one test circuit." By noon, after working at a frenzied pace, the job was done. Tom thanked each one of the men personally. Then everyone went to eat lunch. After the meal, Hank Sterling asked, "How about a detection test to see how she works?" "Coming right up," Tom said. "Want to skipper the jetmarine, Bud?" "Sure do!" "Okay. Pick out a couple of men for a crew and take her down." Tom produced a hydrographic chart of the waters around Fearing and marked out a test area. "Cruise around there for an hour and we'll try to spot you in the _Sea Hound_." "Hide and seek, eh?" Bud grinned and snapped a salute, then left to supervise the relaunching of the jetmarine.