Paul and his companions were booked as passengers on a grain ship bound for Rome. There was no such thing as a passenger ship, so this was a commercial vessel and Paul’s passage was likely commandeered by the Romans (Dunn, Beginning form Jerusalem, 995). It is possible these was a financial bonus for delivering grain to Rome before the end of the sailing season, explaining why the captain attempted to sail so late in the season. Acts 27:9 tells us that they did not sail until after the Day of Atonement (“the Fast”), which is late September, early October. Paul advises they not sail until spring, since after mid-November sailing to Rome would be impossible.
Ancient boats were not built to handle sailing into the wind, and the sailors try to keep the ship together during the storm. Verse 17 describes the lashing of ropes to hold the ship in one piece, it is difficult to know how they did this. The area to the south of Crete was a kind of “Bermuda Triangle,” a part of the sea feared by the sailors. They were in no real danger of going that far south, but they knew that the sandbars were dangerous. Cargo is tossed overboard, then the extra equipment. This was done to lighten the load (although one wonders if the extra weight would keep them from being overturned). The clouds are so thick that they cannot make a sighting on stars or the sun, so they have no way of knowing which way the are headed. The sailors become despondent, thinking they are not going to survive.
Paul speaks again and tells the captain that he has been told “by an angel” that they will all survive. There is a bit of “I told you so” in his speech, but it is not an angry condemnation either. Paul knew what he was talking about in the first place, and now his knowledge was based on something more that sailing skill, it was based on divine revelation!
Paul encourages them, and tells them that he knows from an angel of God that they will survive, even though the ship will be destroyed. Why an angel? In other cases, the Lord simply speaks directly to Paul. This is likely an accommodation to the Roman sailors who would have no idea who “The Lord” is, or respect his revelation over their own superstitions and beliefs. An angel can be taken as a “divine messenger” here.
Paul’s message (verses 23-25) is that they will all survive because the God he serves has told him so. This speech is a remarkable statement of faith: It is the God whom Paul belongs that will save the people on the ship. The God Paul worships is the God who is in divine control of these events. Paul is once again promised that he will stand trial before Caesar despite the fact that the ship will run aground. No one will be lost even if the ship is destroyed.