A friend in a kayak attempted to push the duck to shore, but the unusual flotation device was soon more than 650 feet from shore.
The RNLI said rescuers were still on their way to the scene when a man on a paddleboard ventured out to tow the inflatable back to the beach.
The paddleboarder was able to bring the duck close enough to shore for the three men to jump out and return to the beach. The inflatable was then blown back out to sea.
The duck was retrieved by RNLI volunteers, who dubbed the inflatable "Quackers" and joked it was their new apprentice crew member.
"With the strong tides and off shore breezes of the Bristol Channel, Appledore RNLI urges people never to take an inflatable toy into the sea. There is no way to control these and they get pulled out from shore within seconds," the RNLI said.