Some trucks are drive on drive off, but operators Bay Ferries Ltd also provide a drop trailer service. On this particular day Armour Transportation had several trailers to go, and the terminal had its two yard shunters ready to run them onto the ferry (and haul off any coming in from Saint John).
Number 1 shunter was a pretty standard looking raised roof Ottawa, but Number 5 (not an Ottawa- but it had no discernible markings) was anything but standard looking.
It was July 25, so like Christmas lights that still adorn some houses by July 25, it is safe to guess that the plow will remain onboard until next winter. Perhaps it works as a counterweight or, based on the operating speed, maybe it is a ground effects air dam.