Boatman's seen in image this way: forever young (7)
I believe the answer is:
ageless
This clue is a double definition.
'boatman's seen in image this way' is the first definition.
('image' less 'age' is 'Im'=boatman's where he set )
'forever young' is the second definition.
(not aging)
(Other definitions for ageless that I've seen before include "Never appearing to grow old" , "not getting on" , "Always youthful" , "Eternally young" , "Eternal - like Peter Pan" .)