Contradiction with Exodus 14:21
This verse describes Moses parting the Red Sea by the power of God rather than by climbing into a boat, contrasting with Mark 6:51 where Jesus calms the wind after climbing into the boat.
Exodus 14:21: And Moses stretched out his hand over the sea; and the LORD caused the sea to go [back] by a strong east wind all that night, and made the sea dry [land], and the waters were divided.
Contradiction with Joshua 10:13
In this verse, God stops the sun and moon, a different type of miraculous control over nature compared to Jesus calming the wind in Mark 6:51.
Joshua 10:13: And the sun stood still, and the moon stayed, until the people had avenged themselves upon their enemies. [Is] not this written in the book of Jasher? So the sun stood still in the midst of heaven, and hasted not to go down about a whole day. [Jasher: or, the upright?]
Contradiction with Jonah 1:15
Here, the sea becomes calm after Jonah is thrown overboard, contrasting with Mark 6:51 where calm is obtained by Jesus entering the boat.
Jonah 1:15: So they took up Jonah, and cast him forth into the sea: and the sea ceased from her raging. [ceased: Heb. stood]
Contradiction with Acts 27:44
The passengers survive a storm by clinging to debris, in contrast to the immediate calming of the storm when Jesus enters the boat in Mark 6:51.
Acts 27:44: And the rest, some on boards, and some on [broken pieces] of the ship. And so it came to pass, that they escaped all safe to land.
Contradiction with Matthew 8:26
Jesus directly rebukes the winds and sea to calm them, which contrasts with Mark 6:51's description where the mere entering of the boat calms the wind.
Matthew 8:26: And he saith unto them, Why are ye fearful, O ye of little faith? Then he arose, and rebuked the winds and the sea; and there was a great calm.