PILOTAGE PRE-PLANNING GUIDE
ning and establish whether the pilot or the vessel itself will issue the warning.
When navigating VTS areas, they should be asked to help notify ships in the area of
the passage of the towed vessel - if deemed necessary.
Bollard pull: An expression signifying the maximum pull of a tug boat. There
should preferably be agreement between bollard pull, towing equipment and the
point at which the towing equipment is attached to the unit being towed. In the majority
of rigs, this is approx. 110 tons (SWL), and if the rig is making headway it will
be almost impossible to exceed this pull.
Catenary: The depth to which a towing wire will descend at a given length and a
given pull. This is a very important factor when navigating areas with low water
depth. A towing wire should under no circumstances be pulled across the sea bed.
An excel sheet that calculates catenery may be forwarded if requested.
Figure 21. towing wire depth
Escort tug: A tug boat that follows as a backstop. It may often be necessary to have
an escort tug to keep the towing operation on course. An escort tug may be a tug
boat that joins the towing operation when passing narrow areas.
Insurance company, authorities or the master in the leading tug may demand the
use of an escort tug.