The man in his seventies was found in the vessel at Ardmore on the Dornoch Firth at around 8pm on Friday after emergency services were called.
Police Scotland said there were no suspicious circumstances.
Meanwhile, the body of a 60-year-old man was found on a beach on the Isle of Ulva, in the Inner Hebrides, at around 8am yesterday morning.
The alarm was raised when a man alerted coastguard officials. A Police Scotland spokesman said: "The death is not being treated as suspicious."