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 TB 55-1900-232-10
In operating the Liverpool Bridle, limit the tension to the safe working load of the
bridle's 15/8-inch wire rope pendant. (Page 3-39)
Except in an emergency, backing down with a tow is not recommended. If a
collision with another ship is imminent and backing down appears necessary, it may
be attempted. (Page 3-39)
If the target is made up bow-to-stern, it will reverse direction and swing into position
when slipped, unless there is too much way on the ship. Too much way on will
cause the target to be towed stern first. Ensure that the target does, in fact, tow
bow first as the target has a tendency to stream aft without reversing itself and will
end up by straddling the towline in a stern-first position. (Page 4-21)
The strain on the towline will be severe if the towed ship contacts heavy ice. Take
special pre- cautions to prevent the chain bridle, chain pendants and hawser from
chafing. An automatic towing machine makes this easier. Avoid towing on the
bitts; they may be torn out by the sudden increases in tension if ice is encountered
when towing at short scope. (Page 4-6)
Every retractable item forward of the tow fair- lead, or flounder plate if used, must
be retracted by the submarine crew to preclude damage to the submarine itself and
to prevent parting of the tow hawser. (Page 4-7)
The submarine's designed towing rig was intended for intra-harbor towing and is not
generally acceptable for open-ocean towing. (Page 4-8)
Few deck fittings on submarines are not designed for loads that are commonly
considered in the design of surface ships. Care must be exercised to ensure that
the safe load capacity of fittings, such as the bullnose fairlead, cleats and padeyes,
is not exceeded. Particular attention must be paid to the loads which may develop
when the submarine yaws. (Page 4-9)
Obtain technical advice prior to any welding to a submarine's pressure hull. (Page
4-9)
Due to the severe sheering tendencies of most submarines, employing active
steering of the tow, as directed by the towing vessel, can be helpful. (Page 4-10)
Because of the great difference in strength between Grade A and Grade B
shackles, pay particular attention to the presence or absence of the HS mark,
indicating a high strength shackle. The user must be sure that proper shackles are
used in the system. (Page 5-29)
Screw-pin shackles, other than the special forged shackles for stoppers, must never
be used for connections in towing rigs. The pin could back out due to the constant
vibration set up by the hydrodynamic actions on the towline. (Page 5-29)
Never weld on forged steel shackles.
The welding process can weaken the
shackle. (Page 5-29)
Never weld detachable links. The welding process can weaken the links. (Page 5-
29)
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