How can I keep my character controller from affecting a rigidbody?

I have a ship with a rigidbody that sails on the ocean. When I have my character controller on the ship and bump up against a wall, the ship acts like it runs into my character. This causes the ship slow down, turn, or generally move erratically depending on the speed of the ship, and what part of the ship the character is bumping.

I want the character to collide with the ship so that I can ride on it, but I don’t want the ship to be influenced in any way by the character. How can I keep my character controller from affecting the ship’s rigidbody?

I set the CharacterController.detectCollisions flag to false, and it seems to have fixed the issue.