A.T. Robertson Commentary Mark 6:48

"And seeing them distressed in rowing, for the wind was contrary unto them, about the fourth watch of the night he cometh unto them, walking on the sea; and he would have passed by them:" — Mark 6:48 (ASV)

Seeing them distressed in rowing (ιδων αυτους βασανιζομενους εν τω ελαυνειν). See also Mt 8:29 for the word βασανιζω, to torture, torment (Matthew 4:24) with a touch-stone, then to distress as here. Papyri have δια βασανων used on slaves like our third degree for criminals. Ελαυνειν is literally to drive as of ships or chariots. They drove the boat with oars. Common in Xenophon for marching.

About the fourth watch of the night (περ τεταρτην φυλακην της νυκτος). That is, between three and six A.M. The wind was

contrary to them (εναντιος αυτοις), that is in their faces and rowing was difficult, "a great wind" (John 6:18), and as a result the disciples had made little progress. They should have been over long before this.

And he would have passed by them (κα ηθελεν παρελθειν αυτους). Only in Mark. He wished to pass by them, praeterire eos (Vulgate). Imperfect tense ηθελεν.

They thought (εδοξαν). A natural conclusion.

And cried out (ανεκραξαν).

Cried up , literally, a shriek of terror, or scream.