Quickly Andy and Terence made their way for'ard to let go the anchor.
When within a couple of hundred yards of the beach the yawl was again put head to wind, and with a splash the anchor plunged to the bottom of the lagoon. But just as Andy was checking the out-rushing cable, a sudden blow from the staysail caught him unawares, and the next instant he was struggling in the sea.
The waves carried the lad clear of the vessel, and in spite of his utmost efforts he was unable to regain the boat. His father hurled a coil of rope, but the line, being wet, became entangled and fell short.
Andy saw that it was impossible to swim back, so with a cheery wave of his arm he pointed towards the surf-beaten shore, and immediately struck out for land.
For an instant Mr. McKay intended to plunge into the sea and accompany his son on his perilous swim, till the thought of the possibility of Blight recovering his senses occurred to him. With Ellerton and Quexo disabled, the margin of safety was not sufficient when only Terence remained to guard the prisoner.
Both lads were surprised to see Mr. McKay rush into the flooded cabin and return with a rifle and a belt of ammunition.
"Don't alarm him," said Andy's father hurriedly. "But there may be sharks about."
Placing the rifle on the fo'c'sle of the heaving vessel, Mr. McKay watched the progress of the swimmer with the greatest concern, at the same time keeping a sharp look-out for the expected appearance of the dreaded dorsal fin of one of the tigers of the deep.
Steadily Andy swam shorewards, keeping up a slow yet powerful side stroke. Now he was in the grip of the ground swell. Once his feet touched bottom, but ere he could obtain a firm footing the "undertow" swept him backwards.
The next instant he was lost to sight in a white-capped roller. The wave broke, then receded, but to the alarm of the anxious watchers there were no signs of the swimmer.