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46 Cards in this Set
- Front
- Back
What is the primary materials used as tension members?
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Wire rope, synthetic fiber lines, and chain are primary materials used as tension members.
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What is often selected as a chafing pendant or bridle because of its abrasion resistance and survivability?
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Chain
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What is the primary tension element of the towline system?
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Tow hawser which is normally wire rope or a synthetic line
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For wire rope in conjunction with an auto. towing machine, a minimum safety factor of ____is appropriate for good ocean tows in good weather?
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Safety Factor of 3, a safety factor of 4 is recommended for routine tows to be conservative
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What is the breaking strenght for wet nylon?
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15% less than dry line
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What is a better suited material for towing applications?
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Polyester line
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What shall be rigged on all tows and is intended for emergency short-term use?
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Secondary tow line often made up with synthetic line
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Where can a secondary towline be rigged to tow?
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From either the bow or the stern
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For small tows what is used as a primary pendant?
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The ships anchor chain
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How long is the floating messenger on a small tow's emergency hawser?
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200 ft. with a small trailing bouy
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What should be used to connect chafing chain to the tow pad and what should not be used?
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A safety shackle should be used, pelican hooks should not be used.
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As a minimum for vessels above 600 L-ton displacement, the secondary towing pendant should be ______ wire rope with the necessary chafing gear?
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1 5/8 inch wire rope
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What are the towline attachment points on U.S. Navy tugs?
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The towing machine or the traction winch
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What are some attachments to the tow that may be at a hard point specifically intended for towing?
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deck padeye, chain stopper, or specialized tow bracket
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What is recommended for planned tows with newly installed attachment points?
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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 |
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The breaking strenght of the line should not exceed ______ of the padeye's bitt, or cleats yield strenght?
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35%
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What is the "'dog" system on a towing machine?
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A pawl or ratchet type system that cannot be released against tension.
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What are the three types of padeyes found in towing?
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-Horizontal padeye
-Vertical free-standing padeye -Towing bracket |
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Chain stoppers are designed to bear ______ of the breaking strength of the chain.
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60%
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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?
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75% - 80%
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What 4 kinds of shackles can be used as towline connectors?
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*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 |
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T or F screw pin shackles can be used for connections in towing rigs?
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False
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T or F cotter pins for shackles can be used for towing?
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False, replace cotter keys with locking bolts with jam nuts.
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In detachable links, what is the safest and most cost-effective method to secure the tapered pin into the link?
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A hairpin
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What are the 3 types of wire rope terminations?
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1. Swaged
2. Spliced 3. Socketed |
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Properly made swaged eyes develop ______% of the strength of the wire?
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85%
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What are the advantages of swaged fittings made of special alloy steels?
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High efficiency and low cost process
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Why are hand spliced eyes so popular?
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Field repair capability
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How can a fiber core wire rope be swaged properly?
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It can be swaged by replacing the fiber core at the termination with a strand of wire
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A wire splice with properly placed wire clips will withstand ______% of the wires breaking strength?
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80%
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What wire termination will withstand 100% of the ropes breaking strength?
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Poured socket (spelter socket)
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What is used to make a poured socket termination?
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Poured zinc
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Spelter socket is prepared IAW NSTM, Chap _____ ?
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NSTM Chap 613
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What are the approved Navy standard thimbles used as end fittings for synthetic line?
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-Thimble with end link
-Closed thimble -Synthetic rope thimble -Nylite thimble |
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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?
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equal to the size of chain used to anchor the tow
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What is the optimal bridle apex angle?
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Between 30-60 degrees
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How do you rig a back up securing system for a towing bridle?
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Lacing wire rope through the chain links and securing it to a second securing point
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How do you verify that both of the bridle legs are the same lenght?
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By counting the links when the rigging is complete.
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What is usually the lead pendant and how long can it be?
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Up to 300 ft. of wire rope
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What is the minimum bridle retrieval pendant size and what safety factor is considered?
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5/8-inch wire rope
safety factor of 4:1 |
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What does the term freshing the nip mean?
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Periodically adjusting the scope of the tow wire to reduce the wear on any one point.
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What is usually selected as the safety link and is sized to have a breaking strength ____ to ____% below the main tow hawser?
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Wire rope with a breaking strength 10 to 15% below the the main tow hawser
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What are the function of the tow bows?
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To keep the towline clear of all deck fittings and furnish a protected area where personnel can pass safely.
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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?
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50,000 lbs
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niska
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back of the neck
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When using a hogging strap what is perferred over using a shackle?
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Saddle like fittings because they have a larger radii
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