Test 3 Flashcards
What is the formula for safe working load?
Breaking strain divided by safety factor
Where is the safe working load marked on a crane?
On the heel of the boom.
How often is cargo gear surveyed or recertified?
Surveyed every five years, and re-certified annually
What are the three motions of pedestal cranes?
Slew, luff, hoist
What does a runner/whip do?
Controls the vertical position of the load
What does a topping lift do?
Controls the height of a conventional (yard and stay) boom
What does a luffing wire do?
Controls the height of the pedestal crane boom
What is slewing?
The motion of a pedestal crane rotating at the base
What is luffing?
The motion of a pedestal crane in which the boom itself moves up and down
What is hoisting?
The motion of the cable or wire actually raising the load
What is “out reach” referred to as in regards to US Coast Guard license questions?
Load radius
How is slewing accomplished on a pedestal crane?
By ring gear and slewing motors.
What are the three types of slewing cranes?
Conventional, low type, heavy lift.
What’s the difference between a conventional and low type crane?
A conventional crane boom is raised by luffing wire, and low type crane boom is raised by hydraulic cylinders.
What is level luffing?
Raising or lowering the boom without appreciable rise or fall of the cargo hook.
When is level luffing most important?
When the careful movement of a load near ground level is required.
What two instances Can level luffing not be achieved?
With conventional yard and stay cargo gear, or low type pedestal crane
What is the safety factor of cargo gear?
Five
What happens when a boom or crane is lowered?
Out reach increases, and the SWL decreases
What are the factors affecting cargo gear selection in a vessel design?
Preferences of potential charters Cargo handling capabilities of anticipated ports of call Likelihood of project cargo bookings Additional weight of cargo gear itself Stability considerations
Cargo gear has a high
Vertical center of gravity
What type of ships carry project cargo?
Heavy lift ship’s
What is safety factor?
The ratio of strength to an expected load
Project cargo is
Too heavy or large to be carried on conventional cargo ships. Has special carriage requirements
What is luffing sometimes referred to as?
Topping the boom
What is the average maximum pulling capacity of a drum winch ?
10–25 tons
What is the term used to describe when a pedestal crane is secured?
Cradled
On a slewing crane what causes brakes to be applied if there’s a loss of power?
A zero voltage device
An automatic shut down if any part of the crane experiences overload is a
Overload safety
A switch which stops the crane if the hoist is raised too high is a
Hoist limit
What stops the crane if less than three wraps are left around the drum?
Empty drum
What stops the boom from going to high or low?
Limit switch
What kind of cargo is typical for a gantry crane?
Containers or bulkers
What are advantages to side loaders?
Minimal impact on stability, more direct cargo movement, cover dock possibilities.
What are disadvantages to a side loader?
Hull strength reduction “hull girder”, elevators take space, less weight capability, smaller parcels
Who tests and certifies cargo gear?
The classification society
What cargo gear is included for testing?
The crane structural assembly, rigging, wire ropes, sheaves, cargo hook, loose gear such as shackles slings and spreaders.
What type of material is used for a stopper?
The same type of material as the mooring line, except in the case of wire, we use a chain stopper.
While inbound or outbound in pilot waters, and anchor is always
Lowered from the hawse and ready to let go
Who typically stands by anchor ready to let go for emergencies?
The chief mate, or a licensed deck officer and a boatswain or AB
Holding power comes from
Weight of the anchor and the scope of the chain
What kind of anchors are mostly used on seagoing vessels?
Stockless
The scope of a chain is usually
5 to 7 times the depth of the water
Where must a ship be positioned when heaving an anchor?
Directly over the anchor
What is SOG?
Speed over the ground
What is the term used to describe the anchor secured into the Haus pipe?
Anchors home
What is located in the Haus pipe to remove mud?
Water washdown jets
A machine used to handle anchors and typically has drums for mooring line handling is known as a
Windlass
A drum on a windlass is referred to as a
Gypsy head
A deeply grooved drum on the winless with sprockets and pockets which engage the links of the anchor chain is the
Wildcat
What prevents a chain from fouling on the wildcat
A stripping bar
A capstain head, drum or gypsy head are all
Drums fitted to the windless
A riding Pawl is a
One way device when set
When a pawl is down
The chain cannot pay out but can be heaved in
When is the only time a riding pawl will be raised?
When the anchor is dropped or lowered
A shot of chain is equal to
15 fathoms or 90 feet
Arranging a mooring line on deck in long bites with half turns at the ends of the bites is known as
Faking
What’s the largest non cargo space aboard ship?
Engine room
What are the the cycles in order on a four stroke?
Intake
Compression/ignition
Power/expansion
Exhaust
When does combustion occur?
At TDC
What type of ignition is diesel?
Compression
What type of ignition is gas?
Spark
Ic engines aboard ship are usually started with
Compressed air, hydraulics or electric
Main engines and generators are started with
Air
Emergency generators may be started by
Hydraulic or battery power
Classification societies require enough air capacity for
12 starts, including reversals
Right handed propellers produce forward thrust when turning
Clockwise
Left handed propellers produce forward thrust when turning
Counter clockwise
The distance a propeller will advance in one revolution
Pitch
Units of pitch
Feet
Pitch is determined by
Angle formed by blade and axis of hub
The least refined fuel oil is
HFO- heavy fuel oil
Marine diesel oil is
More refined than HFO and has a lower viscosity
What is the cleanest fuel?
Natural gas
What type of fuel is not used for large engines?
Gasoline
What are the requirements of MARPOL Annex VI?
EST emission control areas
Worldwide limits on NOx and SOx
EST preclusions for deliberate emissions of ozone depleting substances
EST fuel quality standards (sulphur by content)
Ushered exhaust gas scrubber technology into marine engineering
Two types of combustion air
Naturally aspirated
Supercharged
PM=
Particulate matter
Emission control areas
Mediterranean Baltic Black Red Gulfs North Antarctic s of lat 60 Caribbean
Where is automation found aboard ship?
HVAC Fuel oil transfer Bilge Waste water treatment Iron mike
Any change in the magnetic field of a coil of wire will cause an electromagnetic force to be induced into the coil.
Faraday’s first law
A device that converts mechanical energy to electrical energy for use in an external circuit
Generator
Hydraulic flow ~
Electrical current
Hydraulic pressure ~
Electrical voltage
Hydraulic resistance ~
Electrical resistance
Describe the flow of energy
Fuel to generators to main/aux buss to transformers to loads
What’s at various junctions?
Circuit breakers
Transformers do what two things?
Step up or down voltage
A buss is a
Distribution node
What two things do busses do?
Receive energy from generators and distribute to loads
What are 5 prominent propulsion modes?
Rudder/propeller Kort nozzle Azipod- mover in pod Cycloidal Z-drive mover in hull
The comparison of theoretical distance traveled to observed distance traveled is
Propeller slip
How do you calculate slip?
1-(observed distance/calculated distance) x 100%
Or
1-(actual travel/pitch travel) x 100%
Formation of vapor bubbles (voids) in water near moving propeller is known as
Cavitation
A propellers tendency to cause the ship to rotate about the vertical axis at slow speeds ahead or astern is known as
Wheel or walking effect
Which direction will a right handed propeller walk a vessel?
Stern to starboard and bow to port
When backing, a right hand propeller walks the vessel
Stern to port and bow to starboard
Fixed pitch propellers advantages
Less apt to damage
No rotation when no power
Less dangerous for mooring
Less risk of propeller entangled in mooring lines
Fixed pitch propeller disadvantages
Too many rpms during adverse weather
Limited range of rpms for maneuvering and power
Controllable pitch propeller advantages
Propel at all engine speed Quick change from ahead/astern Improve efficiency Main engine runs at optimum rpm Easily combined with shaft generator Stops with max power Changing one blade is possible
Controllable pitch disadvantage
Vulnerable to damage due to hydraulic components and seals Oil pollution Creep at 0 pitch Unusual handling characteristics Loss of steering in neutral position Difficult to repair Price Still turns at all stop
What type of propeller is most likely to foul a mooring line?
Controllable pitch
What is a nozzle on a propeller?
The shroud
A thrust bearing is designed to
Transmit the thrust of the propeller to the vessel
Bow and stern thrusters are
Great at speeds less than 3 kt
Can be a propeller in a fixed transverse tunnel
Can be retractable or swiveling
Can be cycloidal
The perfect propulsion system for precise maneuvering even under adverse conditions
Vogt-Schneider cycloidal propulsion
The VSP magnitude and direction of thrust is
Infinitely variable
With VSP the magnitude of thrust is determined by the
Rotational speed of the disk
With VSP the direction of thrust is determined by the
Blade angle
Stabilizers can reduce rolling up to
80-90%
What on a ship utilizes faradays law?
Shipboard generators
Phases for dc power
None
Phases for ac power
Single and 3
Dc power is found
In nature
Ie static electricity
Lightning
Dc current can be produced by
Battery-and stores
Dc generators
Fuel cell
Solar cell
Dc is preferable for
Emergency lighting and winch motors
Can we utilize static electricity?
No
Which current is used for most power loads?
Ac
All electrical generators produce
Ac current
The rate at which the polarity is reversed is called
Frequency
Frequency=
(#poles x rpm) divided by 60
Frequency is determined by
Speed and construction of the generator
Common shipboard frequency
60 Hz (U.S) 50 Hz (Europe)
Essentially, three single phase generators have been placed in one machine
3 phase ac
Which phase is common for machinery?
3
Which phase is common for lights and electronics?
Single
Advantages to 3 phase
Universally for transmission of ac Higher power to weight ratio of alternators Cheaper Less line to transmit Self starting Instantaneous power is steadier Better power factor Less ripple effect when rectified into ac
UPS
Uninterrupted power supply
Ups consists of a
Battery, battery charger, and inverter to convert dc to ac.
A ups provides
Temporary electrical power in case of main power disruption
An emergency generator is typically a
Small diesel generator
Main components in ships electrical power system
Fuel Heat Generators Electrical busses Transformers Circuit breaker Loads
Reverse power relays
Prevent generators from becoming motorized if one fails
Name three electrical protection devices
Fuses circuit breakers and reverse power relays
Dc frequency =
0
Typical ac loads on ship
HVAC Bridge electronics Accommodations Lighting 3 phase motors
