Following what is thought to have been a collision with a larger vessel in very poor visibility, the motor cruiser began taking on water and the two people on board prepared to abandon to their life-raft.
With both lifeboats underway, the Pilot Boarding Vessel Venus arrived first on scene and took the two sailors on board to safety.
The volunteer crew of Cleethorpes RNLI arrived very shortly after and witnessed the vessel sinking completely just 25 minutes after the mayday call.
Following retrieval of the life-raft, both the charity’s lifeboats and the pilot vessel made their way into Grimsby Docks, where the casualties were checked over and found to require no medical attention.
Daniel Cooper, Cleethorpes RNLI Lifeboat Operations Manager, said: “This was an early wake-up call for our volunteer crew who managed to respond very quickly and launched the lifeboat within six minutes of the request for their assistance.
“Although the incident resulted in the complete loss of the motor vessel, we at the lifeboat station are relieved that the people on board were so swiftly brought to safety, and thank the master and crew of the Venus for their prompt and professional response.”
The Marine Accident Investigation Branch has been informed of the incident.