Mystery in the Channel — Freeman Wills Crofts

One fine June afternoon the passenger steamer 'Chichester' is halfway to Dieppe when she encounters a yacht, 'The Nymph', in mid-channel.
The Nymph appears to be unmanned and closer inspection reveals the sinister truth; her only occupants are two corpses. Was it suicide or murder and where are the crew?
Mackintosh, the 'Chichester's' third officer, navigates The Nymph back to Newhaven, where Constable Turnbull finds there is more in this tragic riddle than he can tackle alone.
So Inspector French of Scotland Yard is called in. The investigation of the problem leads him into some tight corners, but with his brilliant blend of imagination and patient logic, French probes to the heart of the mystery.