John Calvin Commentary Acts 21:1

"And when it came to pass that were parted from them and had set sail, we came with a straight course unto Cos, and the next day unto Rhodes, and from thence unto Patara:" — Acts 21:1 (ASV)

Luke briefly recounts the course of his sailing. He does this not only to lend credibility to the account, so that we may know what was done in every place, but also so that readers may consider for themselves Paul's invincible and heroic fortitude.

This fortitude is shown in how Paul would rather be tossed and troubled with such long, difficult, and troublesome journeys to serve Christ than provide for his own comfort.

When Luke says that they were drawn and pulled away, this does not simply refer to the distance of the places. Instead, it is because the brothers stood on the shore for as long as they could see the ship in which Paul and his companions were carried. Luke also names the havens where the ship arrived so that we may know that they sailed quietly, without trouble from storms.

As for the location of the cities he mentions, let us consult geographers; for me, it is sufficient to show Luke’s purpose.