Granton Harbour is reasonably served by Lothian Transport buses.
If you don’t have a lot of stuff to take down to the boat, try the bus.
Services to Granton are:
Royal Forth Yacht Club Lochinvar Drive, code 36253256,
Number 47 to West End – Penicuik – Timetable
Granton Square west side, code 36238465
Number 47 arriving at Granton
Number 16 to Colinton Timetable
Granton Square East side code 36237257
Number 19 from/to Kings Road via West End – Timetable
Granton Harbour code 36238562
Number 16 – to Silverknowes
There is also a Number 200 bus through Granton Square which goes direct to the Airport. Details and Timetable