Volunteers at St Helier Lifeboat Station in Jersey have walked out amid claims Andy Hibbs was "bullied" by senior management at the RNLI.
The RNLI said it asked Mr Hibbs to stand down "due to serious breaches of the RNLI's Volunteer Code of Conduct".
Claims of bullying are taken "very seriously" and are being investigated, the RNLI said.
Mr Hibbs said he thought the organisation was breaking Jersey's laws and said he is "humbled" by the support of his crew.
Officials from the RNLI met the crew on Thursday evening after complaints were made against Mr Hibbs, the BBC understands.
More on St Helier lifeboat crew resigning, and other Jersey news
Mr Hibbs said: "I was sacked pretty much. The whole thing was just a joke.
"I was being bullied by senior management in the RNLI and I refused to accept it."
A statement from the RNLI said the situation was "incredibly complex" and a "confidential process".
It said: "The RNLI has asked one volunteer at St Helier lifeboat station to stand down with immediate effect.
"We have worked closely with the volunteer for some time but have been unable to resolve a serious breakdown in the relationship between the individual and the charity.
"Unfortunately this impacted on the RNLI's ability to effectively deliver a safe and effective rescue service from St Helier.
"Other volunteers have chosen to step down, which has forced the RNLI to declare the St Helier lifeboats off service temporarily.
"We understand the impact of standing down volunteers and we do not take such decisions lightly."
The St Helier lifeboat should be back in service in a few days, the RNLI said.
A former member of Jersey's RNLI has said there will be a protest held on Sunday.
Paul Battrick said there would be a "silent gathering" at 10:00 BST to support the volunteer crew members.
He said he hoped the protest will get the RNLI "to see sense".
Jersey will have lifeboat cover from the other Channel Islands stations - St Catherine's, St Peter Port and Alderney.
All 25 members of a lifeboat crew have resigned in protest at the sacking of their coxswain.