It might be a good omen, or a bad one.

If a storm, their frail boat would run a terrible risk of being swamped; but if rain should accompany it, there might be a chance of collecting a little water upon a tarpaulin that lay at the bottom.
As it turned out, no rain fell, though there arose what might be called a storm.

The breeze, springing up at an early hour of the day, commenced increasing after sunset.
It was the first of any consequence they had encountered since taking to the boat; and it blew right in the direction whither they intended steering.
With the freshening of the wind, as it came cool upon his brow, the castaway captain seemed to become inspired with a slight hope.

It was the same with Murtagh and the Malay.
"If we only had a sail," muttered the captain, with a sigh.
"Sail, cappen--lookee talpolin!" said Saloo, speaking in "pigeon English," and pointing to the tarpaulin in the bottom of the boat.

"Why no him makee sail ?" "Yis, indade; why not ?" questioned the Irishman.
"Comee, Multa! you help me; we step one oal--it makee mass--we lig him up little time." "All roight, Sloo," responded Murtagh, leaning over and seizing one of the oars, while the Malay lifted the tarpaulin from where it lay folded up, and commenced shaking the creases out of it.
With the dexterity of a practised sailor, Murtagh soon had the oar upright, and its end "stepped," between two ribs of the boat, and firmly lashed to one of the strong planks that served as seats.