"I suppose it's safe," remarked Rix.
"With due precautions—yes," rejoined Kapitan Schwalbe. "At any rate, petrol we must have. Where's the chart? Ah, there we are! It looks a fairly easy place to approach, don't you think? The only danger from a navigation point is apparently this ledge of rocks—Lost Chance Reef, it's called. What unpleasant names these Englishmen give to their coasts!"
At that moment the Unter-leutnant, who happened to be at the conning-tower periscope, reported that a large vessel was bearing down towards them.
Kapitan Schwalbe hurried to the conning-tower. The object depicted was that of a modern tank-vessel about four hundred feet in length. She was low in the water, showing that she was well laden. In place of masts she had four stumpy poles supporting derricks. Right aft was the single funnel. The navigation bridge was well for'ard, connected with another bridge just in front of the funnel by a long slender gangway.
"An oil-tank homeward bound!" exclaimed Kapitan Schwalbe. "Just what we want to fall in with. All being well, there will be no necessity to visit either Port Treherne or St. Mena's Island. Ach! When we have taken what we require we will set fire to the ship, and the English will have a splendid view of a maritime bonfire."
The crew were ordered to their stations, the ballast tanks "blown", and U75 rose to the surface instead of "running awash", since the Kapitan had resolved to stop the tank by gun-fire.
Even then the waves were running so high that the guns' crews were almost constantly up to their knees in water.
Somewhat to the surprise of the submarine's officers and crew, the tank-steamer made no attempt to escape. The firing of a shot across her bows and the display of the black cross ensign were enough to cause the skipper to reverse her engines.
In less than five minutes, the oil-vessel was rolling in the trough of the sea and drifting slowly to leeward. Yet it was a somewhat remarkable circumstance that no attempt was made to lower the red ensign that was proudly displayed at the stern.
Kapitan Schwalbe, with his intimate knowledge of navigation, knew that the only way possible to board the prize was to run to leeward of her, and let the hull of the large vessel serve as a breakwater. He also knew that the submarine would have to be constantly under way during the boarding operations, otherwise the tank-vessel, offering considerable resistance to the wind, would drift down upon U75, whose leeway was almost unappreciable.