The sailors might waver in their wanting to continue. It was important to keep these sailors on their jobs. And it was important to continue to find more sailors. At times some Christians decide to leave the job of manning the ship. It is our duty to get them back to the ship.
Every person is important in the church.
For the church to take the message of the gospel effectively, every person needs to be manning his station. For the church to grow spiritually, every person needs to be manning his station well. For the church to fight the battle for truth against Satan, every person needs to work his best at his station. Be the good sailor you should be. Read the Bible to learn what you should do.