He was puzzled by the discovery that the awkward craft was traveling too far to the westward, until he remembered that the tide had turned, and that the current was either slack or running in the opposite direction.
Changing the paddle to the starboard side, he soon corrected this deviation in the route.

But he had been carried already a hundred yards or more out of the straight line.

To reach the two pointed rocks that marked the entrance to the secret channel, he was obliged to creep back along the whole shoreward face of the Grand-pere; and to this accident was due a surprise that ranked high in a day replete with marvels.
When the catamaran rounded the last outlying crag, and they were all straining their eyes to find the sentinel pillars, they became aware that a small boat was being pulled cautiously toward them from the opposite side of the rock.
Iris gasped.

She heard Hozier mutter under his breath, while San Benavides revealed his dismay by an oath and a convulsive tightening of the hands that rested on the girl's shoulders.
Hozier strove with a few desperate strokes of the paddle to reach the shadows of the passage before the catamaran was seen by the boat's occupants.

He might have succeeded.