"Last night an angel of the God whose I am and whom I serve stood beside me and said, 'Do not be afraid, Paul. You must stand trial before Caesar; and God has graciously given you the lives of all who sail with you.'" NIV translation
Paul explains to the men that, since they are on the ship with him, God has granted them safety and they will not lose their lives. This is a picture of our lives and Christ. If we are with Him, then we, too, have been granted eternal life. It is also what happened in the days of Noah and the ark. In all of these cases, it is simply because of the grace of God that lives are spared.
"'So keep up your courage, men, for I have faith in God that it will happen just as he told me. Nevertheless, we must run aground on some island.'" NIV translation
Paul encourages the men by his faith but reminds them that their choice has consequences and therefore they must run aground somewhere.
This passage reminds us that, when we get out of the will of God for our lives, things happen. This is not God punishing us but simply the fact that our choices have consequences. Even in our bad choices, we are still God's children and He is behind the scenes looking out for our best interests.
"On the fourteenth night we were still being driven across the Adriatic Sea, when about midnight the sailors sensed they were approaching land. They took soundings and found that the water was a hundred and twenty feet deep. A short time later they took soundings again and found it was ninety feet deep. Fearing that we would be dashed against the rocks, they dropped four anchors from the stern and prayed for daylight." NIV translation
So, after fourteen days they were approaching land. They measured the depth of the water and found that it was getting shallower (they were approaching land). They did everything they could to slow the ship down and then prayed for morning so that they could see. It is interesting to note that they prayed after they had done everything else they could think of. Instead of resting in the promise that God had given Paul, they still trusted in their own hands. It seems that many of us (Christians) actually do the same thing, instead of turning to God first, many times it is our last resort.
"In an attempt to escape from the ship, the sailors let the lifeboat down into the sea, pretending they were going to lower some anchors from the bow. Then Paul said to the centurion and the soldiers, 'Unless these men stay with the ship, you cannot be saved.'" NIV translation
So the sailors were terrified and tried to escape into the lifeboat. Paul informed the soldiers that they must stay with the ship for God promised that, if they did, their lives would be spared. The soldiers were supposed to get the prisoners to Rome safely and, if they escaped, the soldiers could lose their life. This, too, is a picture of how many times during the storms of life we forget about what God has told us and how He will protect us and we try to do things on our own. Like the sailors here, we must stay in God's will (the ship) and we can be assured that God is going to take care of us.