Louise Patten said Charles Lightoller, who was second officer on the ship which sank when it hit an iceberg on its maiden voyage in 1912, said an order to steer the ship away from the danger was misunderstood.
She said that different steering systems were used for steamships and sailing ships and her grandfather maintained this caused confusion when an order was given to turn the ship.
Mrs Patten said: “Crucially, the two steering systems were the complete opposite of one another. So a command to turn ‘hard a-starboard' meant turn the wheel right under one system and left under the other.
“The steersman panicked and the reason why Titanic hit the iceberg, which has never come to light before, is because he turned the wheel the wrong way.”
Mrs Patten lived with her grandmother who told her the story. Her novel, Good As Gold, tells the story of a banker who escapes the sinking ship.