Member of the public called the lookout concerned about a yacht at anchor off Splash Point. Nobody could be seen on board. NCI already had the yacht under observation. Yacht had been seen earlier that evening transiting west to east past the lookout. No name visible. The yacht was in a dangerous position should the anchor fail. It was not moored in a designated small vessels anchor ground in Seaford Bay. No crew visible on deck but at 1730 whilst under observation the mast top anchor light was observed being switched on suggesting someone was on board. Early the following morning the yacht had broken free of the anchor hold and was washed onto rocks and capsized. Two persons had been rescued from the yacht by the RNLI.