see http://www.isle-of-man.com/manxnotebook/famhist/genealgy/civil.htm re civil records (there are effectively very few from this period) - parish records covered at http://www.isle-of-man.com/manxnotebook/famhist/genealgy/church.htm
the IGI is reasonably complete for the Island so if you can't find it there then barring a transcription error in the 1911 transcription upon which any certificate issued by IoM general registry is based then it doesn't exist.

BTW ages in manifests are often lower than they should be