In the captain's case, the fresh air recommended was the air of the sea.

At the same time he was forbidden to receive either letters or telegrams, during his absence from town, until the doctor had seen him again.

These instructions pointed, in Captain Bennydeck's estimation, to sailing for pleasure's sake, and therefore to hiring a yacht.
The third and last letter announced that the yacht had been found, and described the captain's plans when the vessel was ready for sea.
He proposed to sail here and there about the Channel, wherever it might please the wind to take him.

Friends would accompany him, but not in any number.

The yacht was not large enough to accommodate comfortably more than one or two guests at a time.