A retractable thruster assembly for a marine vessel has a propeller unit, a motor, a housing and a drive shaft linking the motor with the propeller unit. An actuator is operable to move the propeller unit from the storage configuration to a deployment configuration in a direction from inboard to outboard, the propeller unit being extended from the hull for use in the deployment configuration. The drive shaft comprises a motor-side universal joint for attachment to the motor and a propeller-side universal joint for attachment to the propeller unit. The universal joints permit folding of the drive shaft at least in the storage configuration. A motor-side telescopic section is disposed adjacent the motor-side universal joint. A propeller-side telescopic section is disposed adjacent the propeller-side universal joint. An intermediate telescopic section is disposed between the motor-side telescopic section and the propeller-side telescopic section.