Navigation Mast
The mast needs to be stiff enough and possibly supported
to reduce excessive vibrations, especially in fast
manoeuvres at high speed.
Shaft
Bearing Supports
The
shaft bearing supports need to be stiff and strong
enough to take the load of the rotating shaft.
Bulwark
The bulwark should be inclined inwards to prevent
the bulwark from touching assisted vessels. Ideally
the bulwark should not be as far to the sides as
possible, but some tens of centimetres inwards to
enable easy stepping onboard without having to jump
the bulwark first.
The
bulwark around aft deck need to be strong enough
to take the whole weight of the tow wire without
shearing, if the tug is equipped with an aft winch
and intended for towing over the stern.
Skeg
The skeg need to be supported inside the hull, not
just welded to the bottom plate. A "soft" skeg may
cause severe vibration throughout the tug, not only
to the skeg itself. The vessel is also supported
by the skeg during dry-docking and it is the first
part to hit the bottom in case of grounding, thus
protecting the propeller nozzles.
