Six French fishermen have been airlifted from a boat that was stricken in 20ft (6m) high waves off Land's End.
Another fishing crew and Sennen Cove RNLI lifeboat went to help but could not get a tow rope to it because of the waves and atrocious weather.
Coastguards were alerted at about 22:00 GMT on Tuesday that the 79ft (24m) La Fanette's engine had failed.
The six crew on board were airlifted from the fishing vessel by a Newquay-based rescue helicopter.
Three yellow Met Office weather warnings are in place until Thursday as Storm Gareth sweeps across the country.
Forecasters said there could be gusts of up to 80mph along coasts in northern England, and there are fears of widespread travel disruption on Wednesday morning.
Capt Sharky Finn from the Newquay coastguard helicopter, said the aircraft was "effectively flying sideways" into a Force 8 gale "with 20ft high waves swirling beneath us".
"We could clearly see the fishing vessel disappearing beneath the swell as we approached," he said.
"Needless to say, it stretched the capabilities of both the crew and the aircraft."