“When He had stopped speaking, He said to Simon, “Launch out into the deep and let down your nets for a catch.”
But Simon answered and said to Him, “Master, we have toiled all night and caught nothing; nevertheless at Your word I will let down the net.” And when they had done this, they caught a great number of fish, and their net was breaking. So they signaled to their partners in the other boat to come and help them. And they came and filled both the boats, so that they began to sink.” Luke 5:4-7 NKJV
Peter logically knew from being out there all night that the fish weren't there. Would he trust his own "fisherman's know-how and experience," or would he trust the Word of Jesus the carpenter?
He began to logically reason with Jesus, but then stopped and made room for the Word of Jesus, "Nevertheless at Your Word I will let down the net." In direct obedience to the Word of Jesus, Peter prepared a net, drew up the anchor and sailed out into the deep. Peter's obedience was almost a reluctant obedience, for Jesus had said "nets," but Peter only let down one.
However with the partial obedience of letting down only one net, Peter caught the biggest haul of fish in his life! There were so many fish that two boats were in danger of sinking with the weight of them!
What a powerful demonstration there was to even Peter's partial obedience. It so impacted him that he fell down at Jesus' feet, repenting of his own sinfulness of doubt and unbelief. Those with him were absolutely amazed at the demonstration of the power of the Word of Jesus through one man's partial obedience.
Imagine what could have happened if Peter had been totally obedient! That one demonstration had such a profound impact upon them that they forsook all and followed Jesus.
Nevertheless is a conjunction connecting Simon Peter’s fruitless experience with God's Divine guidance. It's as if Simon Peter was fully acknowledging what he was about to do made no sense at all in light of the circumstances. But this is not blind faith; this is a confidence that the spoken Word of God will trump the futile imaginations of men.
Nevertheless is a word that changed the course of Simon's life. He had been moving in the realm of self-will; but now he will learn the wisdom of obeying God.