John Chrysostom

Paul said to the centurion and to the soldiers, "Except these abide in the ship, ye cannot be saved": so saying, not on this account, but that he might restrain them, and the prophecy might not fall to the ground. Accordingly observe how the centurion does as he bids him, insomuch that he even let the boat go, and destroyed it. And if the sailors did not as yet comply with his bidding, yet afterwards they do so: for in fact this is a reckless sort of people.

Homily on Acts 53 ↗

Oecumenius

But when he said, "Unless these stay in the ship, you cannot be saved," Paul spoke wisely, so as to hold them and not let the prophecy fail. Therefore when they saw that their lack of resolve had put them in danger, then they began to obey him. For if they had complied under the notion of fate, although they were Gentiles, having ignored the counsel of the holy man they would have permitted the sailors to depart. [AMMONIUS]

Commentary on Acts ↗

Bede

"Unless these men stay in the ship, you cannot be saved," etc. Because in the danger of shipwreck, the knowledge of sailors who were experienced in the sea was more beneficial than the weapons of soldiers, they were therefore more likely to control the boat than to let the sailors be cast away.

Commentary on Acts ↗