Spray blew about in showers; the foam stood in a ridge amidships and boiled high about the stern.

It seemed to Agatha that they were traveling like a toboggan, and she had an exhilarating sense of speed that banished the thought of danger.
"How fast are we going ?" she shouted.
"I don't know.

Five miles an hour, perhaps!" It sounded ridiculous; Agatha had felt as if they were flying.

Then she saw that skill was needed to keep the canoe before the wind and Thirlwell ran two risks.

If he let the craft fall off too far, the sail would swing across and she might be capsized by the shock; if he let her swerve to windward, the following wave would break on board and she would be swamped.