Charles Ellicott Commentary Acts 27:31

"Paul said to the centurion and to the soldiers, Except these abide in the ship, ye cannot be saved." — Acts 27:31 (ASV)

Except these abide in the ship . . .—We scarcely need to concern ourselves with the question of to what extent the divine promise depended on this specified contingency. Prompt vigor, and clear discernment of what was needed at that moment, were expressed in the Apostle’s words. The assurance that had been graciously given was to be realized, not through the apathy of blind fatalism, but by human cooperation.

It was obvious that landsmen, such as the soldiers and prisoners, would be completely incapable of handling a large ship in such critical conditions. Consequently, from a human perspective, the presence of the sailors was essential for the safety of the others. St. Paul's thoughtful vigilance, even in those hours of darkness, was highly characteristic.