Francesco Schettino told his trial in Italy that as the Concordia came perilously close to the rocky coast of Giglio island, he ordered his helmsman to steer to the left, but the crewman reacted slowly and did not carry out the manoeuvre.
Mr Schettino said: "There wouldn't have been the crash had the helmsman promptly and properly carried out the order."
His comments came after asking the court in Grosseto for permission to speak while technical experts were discussing how much the helmsman's action might have contributed to the collision.
Mr Schettino has previously said the reef was not on his charts and the ship's owners should shoulder some blame. If convicted, he faces 20 years in prison.
The helmsman, Jacob Rusli Bin, is one of five Costa employees who were granted plea bargains in a separate hearing.
Investigators have said language problems between the Italian captain and the Indonesian-born helmsman might have played a role in the botched manoeuvre.
Mr Schettino also asked the judge to allow him to inspect the crippled liner which was last week raised upright in a salvage operation.