The station’s Severn class Christopher Pearce launched at 6.25pm after the man, who was sailing for the port of Holyhead in North Wales, had become ill and made the correct decision to call for help.
Due to the vessel’s location, a large tanker diverted from its course to shelter the stricken craft.
Once the lifeboat arrived minutes later, one volunteer was transferred onto the boat with the lone sailor, who was able to rest while the RNLI crew took his 27ft vessel in tow.
About 20 minutes into the tow, the crew member aboard reported the sailor’s condition was worsening and he was developing chest pains and breathing issues.
The tow was then released and the lifeboat went back alongside to transfer another crew member aboard with more medical equipment.
The casualty’s condition continued to worsen and the need for an immediate evacuation of was needed, so the casualty was transferred to the lifeboat ahead of a medevac by helicopter from HM Coastguard while his boat was brought into Holyhead.
Coxswain Tony Price said: “All at Holyhead RNLI are hoping the man made a swift recovery.”