Wheat is best understood as a reference to what remained of the ship’s cargo, rather than to the ship’s provisions. Evidently they had not previously thrown overboard all the ship’s cargo (see v. 18). The reason for throwing the ship’s cargo overboard initially was to keep the ship from being swamped in the storm; the present reason for the throwing the remainder of the cargo overboard seems to be that the ship would “float high” and would go up on the beach as far as possible.

Quoted with permission from Newman, Barclay M. and Nida, Eugene A. A Handbook on The Acts of the Apostles. (UBS Handbook Series). New York: UBS, 1972. For this and other handbooks for translators see here .