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 TB 55-1900-232-10
d.
Drum or sheave grooves that have become rough or corrugated through wear
e.
Inadequate diameter of drum or sheave
f.
Improper winding on drum
g.
Improper or insufficient lubrication
h.
Exposure to corrosive fluids
i.
Exposure to excess heat or electric arcing
j.
Lack of protection against moisture and salt water
k.
Kinks or hockles.
If wire rope is struck by lightning, it should be inspected and considered for replacement.
It is important to maintain a minimum and evenly- distributed wear. Special attention should be given to possible chafing
points where the wire rope passes over chocks, bitts, stern rollers, etc. Even though no particular wear may be noticed, it
is advisable to freshen the nip at least once a watch in order to change the location of possible wear
B-10 WIRE ROPE SPECIFICATIONS
Navy towing hawsers are invariably 6 x 37 class, pre-formed, right-lay Improved Plow Steel (IPS), coated (galvanized)
wire rope. Hawsers should be right-hand lay where the wire winds on the winch drum from the underside and where the
bitter end is secured on the port side of the drum This covers most Navy cases since the right-lay wire has the tendency
to wind tightly against the preceding wrap in this orientation.
For the port drum on the ATS 1 and ARS 50 Classes, where the hawser is secured to the starboard flange, a left-lay wire
be would ideal. To avoid the complication of having different lay hawsers, use a right-lay wire on the port drum, spooling
it as follows:
a.
Ensure that the wire is pretensioned at 5 percent of its breaking strength.
b.
Wind the first layer slowly, ensuring that each wrap is tight against the previous wrap. Use a heavy maul or hammer
to obtain a tight fit. Protect the wire as necessary during any hammering action.
c.
Do not routinely spool wire off the first layer. Retain the first layer as a semi-permanent foundation for subsequent
layers
Navy towing hawsers are of three types:
a.
2-inch diameter, fiber core
b.
2-inch diameter, fiber core
c.
2-inch diameter, Independent Wire Rope Core (IWRC)
Table B-1 lists the wire hawsers carried by each Navy towing ship class. Table B-2 provides the strength and weight per
foot of 6 x 37 class IPS marine ropes. Data is provided for a variety of wire rope sizes for convenience, because
pendants, bridles and wire ropes for salvage use are not restricted to the three common sizes.
Attachment A to this appendix provides a procure- ment specification for U.S. Navy towing hawsers. This can be used
when procuring a new hawser(s) from manufacturers/vendors, as opposed to purchasing from existing Navy stock. Note
that Section 3.1 of Attachment A to this appendix must be adapted to the particular ship involved Also note that drawn
galvanized wire is the preferred specification, with strength equal to that of bright, i.e., uncoated, wire.
B-11 WIRE ROPE TERMINATIONS
Wire rope towing hawsers are usually terminated with a closed, poured or "Spelter"
B-10
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