Mayday call triggered after vessel broke from mooring in North Ayrshire and started to drift without power.
Coastguard teams were alerted to a person in the water at Donmouth in Aberdeen on Thursday evening.
The owners raised the alarm when the pet went over the edge at Birsay, Orkney, on Saturday night.
Coastguard crews answered a Mayday call after the boat sank off the north-west Scottish coast.
Maritime and Coastguard Agency say man taken to hospital via helicopter following incident on Saturday night.