Dana is describing a particularly well kept ship:
"There was no foolish gilding and gingerbread work, to take the eye of landsmen and passengers, but everything was “ship-shape and Bristol fashion.” There was no rust, no dirt, no rigging hanging slack, no fag ends of ropes and “Irish pendants” aloft, and the yards were squared “to a t” by lifts and braces.

I could find no definition for "fag" in this context. Perhaps "frayed" ? My dictionary gives as sixth meaning for whip "to wind cord or thread around the end of a rope to keep it from fraying.(It has to be sewed through the rope at start and finish to keep it in place.)