When one clicks on "All tunes used with Come Thou Fount of Every Blessing", there are two tunes listed that are called MARINERS; one of them is actually SICILIAN MARINERS, but the other one may also be SICILIAN MARINERS or it may be something else; hard to tell, since there are no page scans or incipits or other identifying characteristics to go by. My guess is that it is a case of SICILIAN MARINERS going by an abridged moniker, but one would have to check The Book of Praise #782, The Hymnary for use in Baptist churches #304, The Hymnary for use in Baptist churches #359, The Hymnary of the United Church of Canada #304, and The Hymnary of the United Church of Canada #359 to be certain.
I also think that the one instance of DISMISSAL is simply an arrangement of SICILIAN MARINERS, not an independent tune.