Littlehampton RNLI’s Atlantic 85 lifeboat launched on Friday to reports of engine failure on a leisure boat half a mile off Felpham shoreline.
The UK Coastguard received an emergency VHF radio call from the skipper stating a warning light was indicating there was water in the fuel tank.
Renée Sherman and its volunteer crew launched at 4.11pm to where the boat had dropped anchor to prevent further drifting in worsening sea conditions, a spokesman confirmed.
They added: “Arriving alongside the casualty the lifeboat crew rigged a tow line in preparation for its recovery, during which it was determined that the casualty’s anchor was wedged in rocks below the water line and was preventing the recovery.
“Lifeboat helmsman Ivan Greer, decided that due to the increase in sea swell and to prevent any possible safety risks to the casualty the anchor rope should be cut.”
The adult male on board agreed, and the lifeboat crew commenced the tow to Littlehampton Marina, where the casualty was safely moored, they said.
The lifeboat returned to the station nearly two hours later, at 6.05pm, where it was refuelled and made ready for service.