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19 Cards in this Set
- Front
- Back
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Why is chain often used as a chaffing pendant?
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Chain is often selected as a chafing pendant or bridle because of its abrasion resistance.
and survivability. |
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Why has wire rope replaced natural fiber lines for towing hawsers?
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Because of its superior
abrasion resistance and strength-to-weight and strength-to-size ratios. |
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For wire rope in new condition, used in conjunction with an automatic towing machine, what is the minimum safety factor appropriate for routine ocean tows in good weather?
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A minimum safety factor of 3
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When is nylon weaker? When it is wet or dry?
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Nylon is weaker when wet than when dry.(Breaking strength for wet nylon line is about 15 percent less than for dry line)
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True or False?
A secondary tow system is rigged to tow from either the bow or stern. |
True.
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What is the secondary towline for ?
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The secondary towline is intended for emergency, short-term use if the main towline fails.
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Where are the towline attachment points on US NAvy tugs?
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Towline attachment points on U.S. Navy tugs are the towing machine or traction winch.
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Bitts on navy ship are designed to withstand a load equal to...?
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3 times the breaking stregnth of the line they are desinde to hold
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What is the most frequent means of attaching a towline to the towed vessel?
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The most frequent means of attaching a towline to the towed vessel is by means of a padeye.
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What are the three types of padeyes found in towing?
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1- Horizontal padeye
2- Vertical free-standing padeye 3- Towing bracket |
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How much breaking strenth of a chain is a chain stopper designed to bear?
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Chain stoppers are designed to
bear only 60% of the breaking strength of the chain. |
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What are fairleads used for?
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Fairleads are used to lead lines around obstructions and align them properly with winches or capstans.
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Can the recommended Safe Working Load found on a shackle be used for towing?
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No, you must use proof loads.
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True or False?
Screw pin shackles can be used for connections in towing rigs. |
False. Screw-pin shackles, other than the special forged shackles for stoppers,
must never be used for connections in towing rigs. |
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When or where would you use cotter keys for shackles or other towing jewlery?
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Never, cotter keys are not used in towing. Replace cotter keys with locking bolts with two jam nuts.
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What are the Three types of wire rope terminations normally used in Navy towing applications?
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Swaged, spliced, and socketed
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A properly made swaged eye develops what percentage of the strength of the wire?
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85 percent
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What is the advantage of using a bridle when towing?
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The stabilizing effect produced by pulling from both legs of the bridle.
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Why is chain the preferred
material for bridles in deep ocean towing? |
Chain’s weight deepens the catenary, and has superior resistance to chafing.
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