(2024 Exam) USN Towing Man Flashcards
Ch 4
What is a Tow Hawser?
The tow hawser is the primary tension element of the towline system. Normally made up of wire rope or synthetic line.
For wire rope in new or very good condition and used in conjunction with an automatic towing machine, a minimum safety factor of ___ is appropriate for routine ocean tows in good weather?
minimum safety factor of 3.
To be on the conservative side and allow for unforeseen occurrences, a safety factor of ____ is recommended for routine tows?
4
Breaking strength for wet nylon line is about ____% less than for dry line?
15 %
What material is better suited for towing applications than Nylon?
Polyester
What do Fairleads do?
Fairleads are used to lead mooring lines around obstructions and align them properly with winches or capstans.
What type of shackles must never be used for connections in towing?
Screw-pin shackles.
What should replace cotter keys for shackles and other fittings in towing operations?
locking bolts with two jam nuts
Can you weld on forged steel shackles? How much does it reduce the strength?
No
By 30%
What three types of wire rope terminations are normally used in Navy towing applications?
Swaged, spliced and socketed.
Stoppers are nominally rated to hold a minimum of ____percent of the breaking strength of the chain or wire for which they have been designed.
60 percent
What do towing bows do?
keep the towline clear of all deck fittings and to furnish a protected area below the sweeping tow hawser where personnel can pass safely.
What is the purpose of horizontal stern rollers?
minimize chafing during heave-in and payout
What is the difference between capstans and gypsy heads?
Capstans rotate on a vertical shaft and Gypsy heads rotate on a horizontal shaft.
On the ARS 50 Class, the vertical stern rollers drop when the side force at mid-barrel height exceeds _______lbs?
50,000 pounds.
