Hard Hearted Fishermen

In Mark, Y'shua is preparing His disciples to operate in a new spiritual regime. After His resurrection, they will have the Holy Spirit and His power available to them. Boats are a significant part of this preparation. In Mark 6 and 8, the disciples do not understand what's going on as they crossed the sea because they had hard hearts. What was it that they were unable to understand? How does that correlate with what Moses was doing in Deuteronomy?