Although a strong swimmer Peter Mosley, 37, was unable to reach a life-ring which was thrown to him, and was last seen “disappearing on the horizon”.
Despite a huge rescue effort, involving several lifeboats and a dozen fishing boats who arrived within minutes, no trace of him was found.
The father-of-two’s body was eventually recovered from the sea 25 miles off Bridlington three weeks later by another fishing boat.
Mr Mosley, who was from a respected local fishing family, had been "over the moon" following the recent birth of his second daughter Peggy-Lee.
He was the only crewmember aboard the Misty Blue, skippered by James Pizer, when the tragedy happened on a “red hot, sweltering” day last July.
The court heard there had been “numerous” problems with the boat and it had been laid up for about 10 days because of electrical problems.
Mr Mosley, from Withernsea, was keen to start earning again, and on July 5, the pair launched around 4am.
They had pulled up their first string of lobster pots and were about a quarter of a mile off the beach off Tunstall, when the gear box "ground to a halt and locked the engine up tight" around 10am, Mr Pizer told the inquest in Hull on Monday.
He said they dropped anchor and were waiting for the tide to ebb.
Mr Pizer had been texting a marine engineer saying the gear box reverse gear had gone, when Mr Mosley, who had stripped down to his shorts and was sunbathing, said he was going for a swim.
“He shouted Geronimo as he jumped in,” he told the hearing. “There was no diverting, he was already in, off the gunwales.
“He must have been six to 10ft away, but by the time I got the life ring, I couldn’t even reach him with a throw.
"He was just getting carried further away. I just saw him disappearing on the horizon.
"The last thing I could see was the life ring and that disappeared. He was borne away by the ebbing tide towards Bridlington.
"He was swimming. He just kept swimming."
Mr Pizer put out a Mayday call and joined in the search on another boat until evening, but without success.
Area coroner Rosemary Baxter concluded that Mr Mosley’s death was due to misadventure "having deliberately gone into the water from the deck of Misty Blue".
His father Arthur Mosley, who was a fisherman for 40 years, paid tribute to his son.
He said: “Pete was big strong lad, who knew his job well and people respected him as a good worker and a good fisherman."
Mr Mosley, who is helping the RNLI spread a safety message and is due to speak at an event in Withernsea on Friday, said they had worked together for around 16 years and he would never have let his son go into the water.
He said: “All skippers need to make crew wear lifejackets. You don’t want anything like this to happen to anyone else.
“What happened shouldn’t have happened. The first call he should have made was to the coastguard to be towed in.”
His partner Gemma Gill, said in a statement to the court that he was a “wonderful partner and father”.
She said he found his happiness in his family, children and fishing, adding: "I miss him every day and I do not know what I will do now. I have to carry on for the sake of the children.”