Test # 2

Question 1

Purpose of masts

Answer 1

Provide elevated location for navigational and/or communication equipment. May carry cargo handling equipment. May serve as a lookout platform.

Question 2

Navigational Masts

Answer 2

• Solid plate
• Pole mast
• Lattice mast
• Wooden sail mast

Question 3

Solid plate mast

Answer 3

Plates are welded to form an elevated stiffened structure. Designed to minimize weight and account for static and dynamic loads. Forward plating rounded for aerodynamic purposes.

Question 4

Pole masts

Answer 4

Designed with weight reduction in mind. Consist of a single heavy-walled pipe attached to the deck with large stays and large base plates. Could even pass through the deck and secured through the use of stools, deck rings, and a tabernacle arrangmennt

Question 5

Lattice masts

Answer 5

Popular design in war ships in the early 20th century. Used to reduce the weight of the structure. Hollow tubing construction offers a light but sturdy design.
Modified lattice masts for large yachts to minimize structure and improve aesthetics

Question 6

Wooden sail masts

Answer 6

Support navigation equipment in modern sail ships.

Question 7

Instrumentation masts

Answer 7

Accommodate weather stations, antennas, scientific instruments, other devices for the purpose of gathering data.
Usually pole mast but separate from ship’s navigation mast

Question 8

Derricks/ cargo masts

Answer 8

Often fitted on the centerline of the ship, close to (or on top of) transverse bulkheads. May be fitted extreme port or starboard.
Shorter, heavier masts specifically for derrick support are called derrick posts, samson posts, or king posts.

Question 9

Cargo mast material

Answer 9

Often tubular sections made up of rolled plates welded together. Lower plates are heavier scantling to provide additional strength. May use high tensile steel to reduce weight of structure (and impact on center of gravity). Size of mast depends on load to be carried.

Question 10

Cargo mast construction

Answer 10

Additional structure will be found under the mast heel to transfer load to structure. May be in the form of partial longitudinal bulkheads, large brackets to transverse bulkheads, pillars, extra girders, and strong beams.
Suitable scarphing of the structure is done to reduce stress concentration points.
Avoid manholes, lightening holes and cut outs in areas of high load.
Need drainage at heel of mast unless mast assembly is completely watertight.
Design must allow for full inspection of supporting structure

Question 11

Booms

Answer 11

Poles or spars that allow an outreach. Usually made of short pieces of heavy seamless tubular steel with center section often heavier to handle bending stresses on the boom.
The heel of the boom will attach to either a derrick or a crane

Question 12

Derrick

Answer 12

Any swinging boom that can reach a cargo hatch opening. Defined as cargo handling equipment having wires for boom topping, side to side movement, and cargo raising all controlled by winch equipment on the deck.
The boom heel is attached to the bottom of the ship’s mast at a derrick stool or through a gooseneck structure directly on the mast. Wires for boom manipulation are passed through sheaves located on the mast and deck. Fittings on the derrick or mast to carry the swivel blocks and wires may be strengthened.

Question 13

Stays

Answer 13

Stays are wires extending from the mast to the deck as a means of providing lateral support for the mast. Stayed masts use strong connection points on the mast as well as on the deck for placement of the wire stays.
Transverse stays are shrouds.
Longitudinal stays are forestays or backstays.

Question 14

Mast support

Answer 14

Masts are supported by at least 2 decks. Masts that pass through the deck and are stepped on a tween deck or lower deck will normally have insert plates fitted at the passage through the deck as well as at the heel of the mast.
Any deck beams that are cut into to allow passage of the mast are strengthened by the fitting of carlings (mast partners).
Masts stepped on the deck will also have a mast house or a bracket arrangement.

Question 15

Cranes

Answer 15

Typically any self-contained cargo handling device. No mast stays or slewing wires. Boom topping and cargo raising are accomplished by integral wiring and wire handling equipment.
Rotation is by a motor acting on a ring gear at the base of the crane.

Question 16

Purposes of cranes

Answer 16

Cargo handling
Launch and recovery of boats
Launch and recovery of underwater scientific instrumentation and devices

Question 17

Davits

Answer 17

Used to place a small craft into and retrieve it from the water. Including survival boats or rafts, rescue boats, work boats.D

Question 18

Davit types

Answer 18

Free fall
Hinged gravity
Fixed arm cantilever
Single arm radial

Question 19

Lifeboat davits

Answer 19

Either directly boarded and launched from davit position OR lowered to an embarkation deck to be lowered and launched. Lowing can be controlled from the deck or from within the lifeboat

Question 20

Requirements for launch of survival craft

Answer 20

Must be by gravity or by means of stored energy that does not rely on the ship’s power supplied. Minimum and maximum lowering speeds are dictated. Must be capable of launching with ship in damaged or ice conditions. Trim of 10 deg + list of 20 deg. For ships over 20k gross tonnes, ship moving at 5 knots in calm water.

Question 21

Davit launching recovery

Answer 21

Done by the use of a winch driven by electric motor with wires passing through the sheaves in the davit arms. May be done manually with a crank mechanism.
- For rescue boats, must be capable of recovery will full rescue complement and equipment at a minimum speed requirement.

Question 22

Deck plating requirements

Answer 22

Deck plating in the vicinity of the davit must be adequately strengthened. Thicker deck plating and additional deck beams. If chocks are capable of retaining moisture, the deck may be a little thicker to account for possible corrosion.

Question 23

Payload handling frames

Answer 23

Hydraulic lifting devices mostly used in support vessels or scientific vessels. Typically located at the stern, but can be mounted transverse (lateral frames).
May come as deployable payloads, set on a 20ft footing for ease of transportation and set up. May be double articulated to launch and recover payload as close to the waterline as possible.
Beams and footing arrangements are welded or bolted to the deck, with a heavy support structure under the main deck

Question 24

Hatchways purpose

Answer 24

Used to facilitate the loading and unloading of a vessel. Layout of hatchways depends on type of cargo and size of ship.
An opening in a deck to provide access to the area below.

Question 25

Strengthening hatchway openings

Answer 25

The removal of a considerable amount of material from the deck has a weakening effect on the structural integrity of the ship. Stress concentrations are created in the opening and is highest near the corners of the opening. - Heavier plating fitted adjacent to opening - Heavy insert plates fitted at corners of opening - Corners are rounded to better distribute stresses - Hatch coamings are fitted - Heavy hatch end beams or deck transverses at the hatch ends - A gusset plate is fitted where longitudinal girder and deck transverse meet at the corner of an opening

Question 26

Position 1

Answer 26

Any hatchways, doorways, vent pipes or ventilator heads found: - Upon the exposed freeboard and raised quarter decks; exposed superstructure deck situated forward of a point located 1/4 L from forward perpendicular

Question 27

Position 2

Answer 27

- Exposed superstructure decks situated abaft a quarter of the ship’s length from the forward perpendicular and located at least one standard height of superstructure above the freeboard deck; OR - Exposed superstructure decks situated forward of points located a quart of the ship’s length from the forward perpendicular and located at least two standard heights of superstructure above the freeboard deck.

Question 28

Hatch coaming requirements

Answer 28

Position 1: 600 mm minimum Position 2: 450 mm minimum Stiffening must be fitted if height of coaming > 600 mm. Takes the form of a horizontal bar placed near the upper edge of the coaming and the use of vertical brackets (stays: strengthened on their free edge, placed in line with existing deck strength members) extending from this bar to the deck. Coamings < 600 mm stiffened along their upper edge

Question 29

Continuation brackets

Answer 29

Where hatch openings are fitted within a region of 60%L about amidships, sides of coaming may be extended past the opening and tapered down to the deck. Called continuation brackets. If no space, interior strengthening of the structure is heavier

Question 30

Hatch Covers Purpose

Answer 30

Provide a weathertight seal to prevent the ingress of water into hold areas. Once fully installed, tends to stiffen the structure of the hatch opening.

Question 31

Hatch cover maintenance

Answer 31

- Overall structure strength is preserved by protecting exposed surfaces of the hatch cover plating and stiffening - Smooth surface and correct profile of trackways , compression bars, all other steel works that are in contact with seals or friction pads - Maintain mechanical or hydraulic powered opening, closing, securing and cleating systems - Replace resting pads, compression bars, seals, etc due to significant wastage, wear, or loss of adjustment capability - Replace seals and other wear components - Maintain drains and non-return valves in hatch covers

Question 32

Types of hatch covers

Answer 32

- Tween Deck hatch cover (fitted flush with deck and not normally wateright) - Wooden Hatch Covers - Steel Pontoon hatch covers

Question 33

Wooden Hatch Covers

Question 34

Steel Pontoon Hatch Covers

Question 35

Advantage of mechanical hatch covers

Answer 35

- Easier made and maintained weathertight - Stronger - Neatly stowed when in the open position - Quickly opened and closed - Less manpower intensive - Safer to open and close

Question 36

Side Rolling Hatch Covers

Answer 36

Usually split at the middle of the hatch opening and can roll transversely or longitudinally. Must be uncleated and lifted off their seals by the use of portable or permanently installed hydraulic jacks. Movement by wire pulls or hydraulically operated rack and pinion arrangement. Restraining wires prevent the running away of a cover in heavy ship movement. Stops are fitted to prevent it from moving too far. A locking device can lock the covers open.

Question 37

Gasket requirements

Answer 37

Soft enough to allow good compression yet hard enough to withstand the forces applied. Mates with a compression bar so that when the cover is cleated, the gasket is compressed enough to ensure a weathertight seal. Suitable drainage inside the line of the gasket in the event of any leakage. In the event of leakage, it must be led to a visible location, through a check valve to prevent the water from flowing in the wrong direction.

Question 38

Single Pull Hatch Covers

Answer 38

Hatch opening is covered with several individual interlocking steel sections.

Question 39

Hinged Hatch Covers

Question 40

Ventilation required for (4)

Answer 40

1. Comfort of crew and passengers 2. Removal of unpleasant, dangerous fumes 3. Supply air to machinery 4. Condensation control

Question 41

Natural ventilation

Answer 41

Carried out throughout the ship but inefficient and not reliable. Skylights in Positions 1 and 2 can be fitted with glass but must have heavy permanently attached steel covers. Skylights to cargo pump rooms or machinery spaces cannot be glass

Question 42

Mechanical Ventilation

Answer 42

1. Large axial flow fans 2. Centrifugal flow fans

Question 43

Axial Flow Fans

Answer 43

Compact and efficient, but relatively noisy. Generally only used in machinery spaces. Fan and motor are located directly within the ventilation trunk

Question 44

Centrifugal Flow Fans

Answer 44

Quiet, efficient, often used for accommodations. Motor is located outside the trunk while fan in placed inside. Often variable or dual speed for better control of air supply and removal. Fitted with automatic shutdown devices in the event of a fire

Question 45

Ventilation ducks

Answer 45

Typically galvanized sheet steel or aluminum for corrosion resistance and reduced weight. Worked in sections and bolted together with suitable gasket material to be airtight. Joints are watertight where placed over electrical equipment. Access ports are provided for inspection, cleaning and maintenance. May be insulated. Avoid the passage of duck work through watertight bulkheads, OR fit a watertight shutter at the bulkhead.

Question 46

Height of ventilator coaming

Answer 46

Position 1: 900 mm Position 2: 760 mm

Question 47

Entry is watertight

Answer 47

- Sliding or hinged metal covers - Shutters - Canvas cover Not necessary if piping height is: Position 1 > 4.5 m Position 2 > 2.3 m

Question 48

Vent Pipes

Answer 48

Fitted to all: - Tanks - Cofferdams - Tunnels - Other compartments where no other ventilation arrangement is provided Allow for the safe escape of vapors from the confined area, allow air to escape when tanks are being filled, prevent vacuum when tanks are being emptied.

Question 49

Position of Vent Pipe

Answer 49

Positioned at the highest part of the space on an outboard corner, away from discharge and filling lines, extends above the load waterline. Size is 25% greater than the filling pipe but not less than 50 mm bore. Height will be increased on freeboard deck due to possibility of shipping water on this deck.

Question 50

Overflow Pipes

Answer 50

Fitted in tanks which can be filled by the ship's pumps or shore pumps. Fitted for 3 reasons: 1. Vent pipe is not large enough to prevent a pressure buildup at max pumping capacity 2. Excessive head of pressure on the tank would exist if the liquid level is allows to reach the top of the vent pipe 3. Accidental overflow would result in pollution. Overflow lines will go to another fuel tank or to a tank reserved for overflow purposes. Size is 125% of filling pipe

Question 51

Sounding Pipes

Answer 51

Used to verify the level of liquid in all tanks and bilges of compartments that are not readily accessible. Fitted as close to the space suction line as this is the lowest part of the tank. As straight as possible, extends to a short distance from the bottom of the tank and must be adequately supported within the tank to prevent movement, vibration, and damage. Diameter is 32 mm unless possibility of freezing (then increase). Tanks are fitted with a means to prevent damage to their bottom plating due to the impact of the sounding tape plumb pop: doubling plate in the tank OR a plug fitted to the bottom end of the sounding pipe (need slots in the piping for liquid to enter). Sounding is done on a regular basis by the same person for consistency of results.