begin pretty
soon to make it work. If a man wanted to break into the boat-house he
wouldn't have very much trouble in doing it, no matter how many
padlocks we put on the doors."

"That's right," spoke up George. "He could dive under the doors, or
smash in the window or cut out a glass and if there wasn't any one on
guard he might never be detected. No, sir, we've got to establish a
guard and the fellow who is on duty must keep up a regular patrol. He
must keep walking around the dock all the time."

"And there may be some other ways by which they will try to get at us
besides injuring our boat," suggested Grant.

"I don't see what," spoke up John quickly. "It's the one boat they are
afraid of and if they can only put the Black Growler out of business
they won't have anything to fear, as far as the outcome of the race is
concerned. What could they do anyway?"

"Oh, I don't know," said Grant. "I can think of a dozen tricks they
might play, any one of which might throw us out of the race."

Grant's words proved to be more prophetic than he had dreamed. That
very afternoon after the boys had taken their daily run over a part of
the triangular course where the great race was to be held, an event
occurred which confirmed his statement and added strength to Sam's
warning.

The Black Growler already had finished her course and under low speed
was moving with the current on her way back to the island where she
belonged.

Suddenly and without any warning whistle, a swift little boat dashed
out from behind one of the small islands which the Black Growler
chanced to be passing at the time and almost before the boys were aware
of what was occurring there was a collision.

"Look out! Look out there!" shouted Fred, who was steering, in his
loudest tones. At the same time he did his utmost to change the course
of the motor-boat. His words of warning, however, were either unheard
or unheeded. There was a sharp collision, for the smaller boat was
moving swiftly. This was followed by the sound of a grinding crash. In
dismay the Go Ahead boys ran to the side of their boat and speedily
discovered that the metal bow of the little boat before them had cut a
long gash which extended below the water's edge. Indeed, it was only by
an effort that the other boat was freed. To all appearances she was
uninjured. On board were two men, plainly belonging to the region.

"What's the matter with you?" called one of the men on the other boat.