They lightened the ship - By casting the wheat into the sea. As they had no hope of saving the cargo, and had no further use for it, they hoped that by throwing the wheat overboard the ship would draw less water, and that thus they would be able to run the vessel on the shore.
Related Commentaries of Acts 27:38
Acts 27:38
38 And when they had eaten enough, they lightened the ship, and cast out the wheat into the sea.