"That one" referred to a crested "comber" that was bearing down towards the swiftly-moving boat. A slight touch on the helm and the fine bows swung round to take the advancing mass of water line on. Administrating a vicious slap to the wave the motor-boat lifted to the crested billow. Spray came hissing aft in solid sheets, pattering on the canvas canopy with a sound similar to that of peas being shaken in a wooden box. She was through, but immediately beyond was another wall of water. Right down until her fore-deck ventilators were hidden plunged the boat. For a moment Derek thought she would never recover herself. The engine faltered. In a second the alert engineer was at the throttle and the "spark". "Water on the mag, sir," he shouted. "I'll have to ease her." "And about time," thought Derek. "Wonder if it's like this all the blinking way?" But soon the boat entered smoother water. The breakers were on the weather side of the bar. Beyond was easier going. Winking the moisture from his eyes, Derek glanced astern. The other boat was making fairly good weather of it, although she looked to be nothing more than a double wing of white foam. "Good enough," declared Derek, and, calling to one of the deck-hands, he gave the wheel over into his care, admonishing him to report immediately Thorbury Head became visible. "Now for a smoke!" he exclaimed, and, pulling out his favourite pipe, he carefully loaded up. Curiosity prompted him to see what the rest of the crew were doing. Grasping the life-lines on the canopy he made his way aft, his sole foothold being the narrow, slippery water-ways. Under the awning were the rest of the crew, lying helpless on top of a nondescript heap of blankets and oilskins, together with the disintegrated rations--fresh beef, "bully", and loaves. In the throes of sea-sickness the hapless "George Robey's Marines" hardly cared whether they were on or in the sea. Clearly nothing could be done to help the luckless victims of _mal de mer_, so Derek made his way back to the steering-well, and, standing behind the coxswain, surveyed the outlook. There was very little to be seen, only a limited expanse of white-crested water, bounded by darkness that was even now struggling for mastery with the first faint tints of a grey dawn. Land, somewhere within three miles, was invisible. All that the helmsman had to depend upon was a small and untested compass fixed in a rather inaccessible and unhandy spot, and within three feet of the mass of metal comprising the six-cylinder motor. There was also the danger of bumping on a drifting mine. Derek realized the peril. Fortunately perhaps for them, the men were in ignorance of the fact that mines had been reported within thirty miles of Fisherton Harbour, and, with an onshore wind and the indraught of the tide, thirty miles was a very small distance for one of these instruments of destruction to drift in forty-eight hours.