They let the sheet run until the big mainsail swung right out, and the sloop drove away, rolling viciously. Short, foam-flecked seas came tumbling after her, but as the tide was running the same way under them, lessening the resistance, very few broke angrily. Frank had learned enough by this time, however, to realize that it would probably be different when the stream turned. In the meanwhile the boat was sailing very fast, with a little ridge of frothing water washing by on either side when she lifted, and a thin shower of spray blowing all over her. Now and then the great sail with the heavy boom beneath it swung upward in an alarming fashion. Frank noticed that Mr. Oliver's eyes were gazing intently before him, and that his hands were clenched tightly upon the tiller. "She seems rather bad to steer," he said. "Yes," said Mr. Oliver, without looking up. "You have to be careful when you're running before a fresh breeze. It's remarkably easy to bring the mainsail over with a bang if you let her fall off too much, and the result of that would probably be to tear the mast out of her. It's considerably worse when there's a big sea coming along behind." Frank glanced astern. The sun had gone and the sky was strewn with ranks of hurrying clouds, while the sea was flecked with smears of white. "Aren't you pressing her a little?" Harry asked. "She'd be easier on the helm if we lowered the peak or tied a reef in." "I'd like to pick up the Hootalquin reef before it's dark," answered Mr. Oliver. "I'm not sure we'll get very much farther to-night. You wanted a sail, and I fancy you're going to be gratified." During the next hour Frank had to admit that this remark was warranted. The breeze steadily freshened, and there was no doubt that the sea was rising. It frothed in a white hillock on either side of the boat, and little trails of foam swirled about her deck. Frank could see that she was overburdened by the sail she was carrying, but Mr. Oliver still sat with a set face at the tiller and showed no desire to leave his post. In the meanwhile it was getting dark. Forest and beach had faded to a faint, shadowy blur and there was only a steadily narrowing stretch of foaming water in front of them. Frank was very wet and the spray beat upon him continually. At length, when the light had almost gone, a dusky patch of something grew out of the gathering gloom ahead, and fancying it to be a rocky point, he felt considerably relieved, because there would be shelter behind it. A minute or two later Mr. Oliver called to the boys. "Get forward and ease the peak down," he ordered. "Then back the jib. We'll tie two reefs in." "Aren't we going in here?" Harry asked. His father shook his head. "No, it's too dark. I could take her through in the daylight, but there are one or two rocks in the channel. We'll have to try for Bannington's."