In the plunges, the waves boiled up there, and one could feel the canoe tremble as she lurched over the tumbling foam.

Then Agatha noted that Thirlwell was not steering with the gale quite abeam; he was edging the craft to windward as far as he could, but the beach got nearer and it was plain that they were drifting sideways while they forged ahead.

Agatha began to doubt if he could keep them off the rocks.
He did not look disturbed.

His glance was fixed to windward and his movements were strangely quick.

Agatha saw that he kept the canoe from capsizing by the skilful use of paddle and sheet.