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46 Cards in this Set

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What is the primary materials used as tension members?
Wire rope, synthetic fiber lines, and chain are primary materials used as tension members.
What is often selected as a chafing pendant or bridle because of its abrasion resistance and survivability?
Chain
What is the primary tension element of the towline system?
Tow hawser which is normally wire rope or a synthetic line
For wire rope in conjunction with an auto. towing machine, a minimum safety factor of ____is appropriate for good ocean tows in good weather?
Safety Factor of 3, a safety factor of 4 is recommended for routine tows to be conservative
What is the breaking strenght for wet nylon?
15% less than dry line
What is a better suited material for towing applications?
Polyester line
What shall be rigged on all tows and is intended for emergency short-term use?
Secondary tow line often made up with synthetic line
Where can a secondary towline be rigged to tow?
From either the bow or the stern
For small tows what is used as a primary pendant?
The ships anchor chain
How long is the floating messenger on a small tow's emergency hawser?
200 ft. with a small trailing bouy
What should be used to connect chafing chain to the tow pad and what should not be used?
A safety shackle should be used, pelican hooks should not be used.
As a minimum for vessels above 600 L-ton displacement, the secondary towing pendant should be ______ wire rope with the necessary chafing gear?
1 5/8 inch wire rope
What are the towline attachment points on U.S. Navy tugs?
The towing machine or the traction winch
What are some attachments to the tow that may be at a hard point specifically intended for towing?
deck padeye, chain stopper, or specialized tow bracket
What is recommended for planned tows with newly installed attachment points?
1. Non destructive testing (NDT)
2. Visual inspection of the attachment point and surrounding area
3. Dye-penetrant test of the padeye or bitt attachment point
The breaking strenght of the line should not exceed ______ of the padeye's bitt, or cleats yield strenght?
35%
What is the "'dog" system on a towing machine?
A pawl or ratchet type system that cannot be released against tension.
What are the three types of padeyes found in towing?
-Horizontal padeye
-Vertical free-standing padeye
-Towing bracket
Chain stoppers are designed to bear ______ of the breaking strength of the chain.
60%
The width of the shackle-pin type padeye plate should occupy ____ - ____ % of the jaw width of the shackle, to prevent it from racking and creating loads?
75% - 80%
What 4 kinds of shackles can be used as towline connectors?
*Type I anchor shackle
Grade A - Regular
Class 3 - Safety Bolt and Nut

*Type I anchor shackle
Grade B - High Strength
Class 3 - Safety Bolt and Nut

*Type II chain shackle
Grade A - Regular
Class 3 - Safety Bolt and Nut

*Type II chain shackle
Grade B - High Strength
Class 3 - Safety Bolt and Nut
T or F screw pin shackles can be used for connections in towing rigs?
False
T or F cotter pins for shackles can be used for towing?
False, replace cotter keys with locking bolts with jam nuts.
In detachable links, what is the safest and most cost-effective method to secure the tapered pin into the link?
A hairpin
What are the 3 types of wire rope terminations?
1. Swaged
2. Spliced
3. Socketed
Properly made swaged eyes develop ______% of the strength of the wire?
85%
What are the advantages of swaged fittings made of special alloy steels?
High efficiency and low cost process
Why are hand spliced eyes so popular?
Field repair capability
How can a fiber core wire rope be swaged properly?
It can be swaged by replacing the fiber core at the termination with a strand of wire
A wire splice with properly placed wire clips will withstand ______% of the wires breaking strength?
80%
What wire termination will withstand 100% of the ropes breaking strength?
Poured socket (spelter socket)
What is used to make a poured socket termination?
Poured zinc
Spelter socket is prepared IAW NSTM, Chap _____ ?
NSTM Chap 613
What are the approved Navy standard thimbles used as end fittings for synthetic line?
-Thimble with end link
-Closed thimble
-Synthetic rope thimble
-Nylite thimble
As a rule of thumb the size of the chain to use for the bridles and the pendants should be at least equal to what?
equal to the size of chain used to anchor the tow
What is the optimal bridle apex angle?
Between 30-60 degrees
How do you rig a back up securing system for a towing bridle?
Lacing wire rope through the chain links and securing it to a second securing point
How do you verify that both of the bridle legs are the same lenght?
By counting the links when the rigging is complete.
What is usually the lead pendant and how long can it be?
Up to 300 ft. of wire rope
What is the minimum bridle retrieval pendant size and what safety factor is considered?
5/8-inch wire rope
safety factor of 4:1
What does the term freshing the nip mean?
Periodically adjusting the scope of the tow wire to reduce the wear on any one point.
What is usually selected as the safety link and is sized to have a breaking strength ____ to ____% below the main tow hawser?
Wire rope with a breaking strength 10 to 15% below the the main tow hawser
What are the function of the tow bows?
To keep the towline clear of all deck fittings and furnish a protected area where personnel can pass safely.
The vertical stern rollers and norman pins onboard the ARS 50 class ships will drop when a load of ________ lbs. or more is applied to mid barrel height?
50,000 lbs
niska
back of the neck
When using a hogging strap what is perferred over using a shackle?
Saddle like fittings because they have a larger radii