Tugs designed to perform ship docking functions are characterized
by small deckhouses and pilothouses and exhaust stacks of minimal
height with lines that often sweep into and compliment the superstructure.
The towing light mast is often arranged so that it can be folded
down, and there usually is a support on the stack or the deckhouse
to hold the mast when it is in the lowered position. These tugs
frequently have large open deck areas, and a fairly wide walkway
on either side of the deckhouse to facilitate the handling of boarding
ladders, which are carried stowed against the pilothouse when underway
to or from a job.
Typical engine total ratings for ship docking service are from
1000 to 4000 horsepower, and although single engine tugs tended
to dominate this application for many decades, in recent years an
increasing number of new construction twin engined tugs have been
used. Tugs used in this type of service will often not have a towing
winch, but instead are fitted with power capstans aft of the deckhouse
to assist in tensioning lines.
The latest trend in ship docking tug design is the use of Z-drives,
and that type of tug will be addressed separately in another article
in this series.
Top: The tug Miriam Moran is shown underway
in an aerial view. Notice the wide transom and dual exhaust stacks
which are indicative of a twin engined tug.
Above: The tug Harriet Moran is shown underway.
The starboard boarding ladder is stowed and lashed to the handrails.
Notice the extensive installation of fenders in addition to a full
hull rubber impact rail.