@Ronald DON'T REMEMBER THE TECHNIACAL NAME BUT IT'S PURPOSE IS NOT TO DAMAGE THE PAINT WORK ON CANADIAN NAVAL SHIPS. THIS TUG IS USED TO DIRECT SHIP INTO HARBOUR AND DOCKING. COLD MOVE OF RCN SHIPS USE THIS TUG FOR CHANGE OF DIRCTION WHILE LARGER TUGS ADRE USED FOR MOVING POWER. PETTY OFFICER FIRST CLASS ELGIN SMITH CD RET'D

@Ronald
My guess is they're traction bars or grip rails to improve contact when pushing barges, preventing the tug from slipping sideways under heavy loads.
If not that, perhaps they're intended as ice-deflecting rails for operations in colder waters