Captain Mayweather was the Earth Cargo Service commanding officer of the ECS Horizon. With his wife, Rianna Mayweather, he was the father of Paul and Travis Mayweather and a daughter.
When Mayweather assumed command of the Horizon, he was a year younger than his son Paul Mayweather was in 2153. Prior to assuming command, he was an engineer. Because of his inexperience and not knowing how to run the bridge, the Horizon fell behind schedule. Facing the loss of his ECA license, he wanted to quit. His wife Rianna would not let him quit. He eventually went on to have a long successful career as the captain of the Horizon. (ENT: "Horizon")
Mayweather kept the artificial gravity on the Horizon as 0.8 G's, believing this "put a little spring in his step", according to Travis. (ENT: "Broken Bow")
When passing near a gas giant, Mayweather would sometimes broadcast the sounds created by the planet's magnetic field through the Horizon's speakers. The Mayweather family would nickname the haunting noises "siren calls" and Travis would later say they gave him nightmares. (ENT: "Sleeping Dogs")
During his time as captain of the Horizon, he had a run-in with Nausicaans and barely survived. Captain Mayweather expected his son Travis to take over as commanding officer aboard the Horizon. He was unhappy when Travis left to serve aboard Enterprise but respected his decision. Travis would learn after his father's death that he had sent a recommendation for his son as a conn position candidate when Captain Jonathan Archer asked. (ENT: "Fortunate Son", "Horizon")
Sometime during the mid-22nd century, the Horizon ran into a class 3 neutronic storm. According to Travis Mayweather, the crew took shelter in the ship's core for six weeks, and during that time, the ship's power generators went down, and they lost the grav-plating and life support. Travis was able to see the bad situation in his father's eyes. (ENT: "The Catwalk")
At some point, he visited Neubilia Prime, where the elders challenged him to a duel and he won. (ENT: "United")
He died while Travis was serving on Enterprise NX-01, after which, his son Paul would succeed him as captain of the Horizon. (ENT: "Horizon")
Travis once promised him that he would see the Terra Nova colony – which he did in 2151. (ENT: "Terra Nova")
This character was only mentioned in dialogue.
The Pocket ENT novel Rosetta gives his name as Paul Mayweather, Sr.