Ship Construction

Question 1

What is the forward collision bulkhead?

Answer 1

5-8% of the ships length not more than 10m from the fwd perpendicular

Question 2

How many watertight bulkheads should a ship have?

Answer 2

A minimum of 4 - FWD collision bulkhead, Aft peak and two bulkheads forming machinery space boundaries.

Question 3

Standard Fire test?

Answer 3

Where bulkhead materials are subjected to heat in a test furnace, an area of 4.65m2 and reaching a temperature of 925oC after an hour.

Question 4

What is An A Class bulkhead?

Answer 4

An A class bulkhead is constructed of steel or an equivalent strength material and suitably stiffened. It will prevent the passage of flames and smoke for 1 hour of the standard fire test. With the unexposed side not reaching more then 139oC and 180oC at any point

Question 5

What is a B Class bulkhead?

Answer 5

A B Class bulkhead is constructed of an approved non combustible material which prevents the passage of flame for 30 mins of the standard fire test. The unexposed side will not reach 139oC within this time and any point will not rise above 225oC

Question 6

What is a Class C bulkhead?

Answer 6

A Class C bulkhead must be constructed from an approved non combustible material.

Question 7

What is a podded thruster?

Answer 7

A podded thruster is where the motor is mounted in the pod, where the motor directly drives the propeller.

Question 8

What is an azimuth thruster?

Answer 8

An Azimuth thruster is similar to podded, however the electrical motor is mounted within the ships hull. These can rotate 360 degrees providing excellent maneuverability

Question 9

What is an Azipod?

Answer 9

An Azipod is a combination of a podded thruster and an azimuth thruster. The motor is mounted in the pod which can rotate 360 degrees.

Question 10

What is a grim wheel?

Answer 10

A grim wheel is a extra free spinning propeller mounted aft of the standard propeller. As the water leaves the standard propeller it creates a vortex. The design of the grim wheel allows the this vortex to spin the wheel. The tips of the grim wheel extend past the tips of the propeller and so this portion creates extra thrust. This extra thrust helps to recover some lost power thus improving efficiency and fuel consumption.

Question 11

What is a kort nozzle?

Answer 11

A kort nozzle is a ducting around the propeller in which the entrance is larger than the propeller and the profile is shaped as a hydrofoil. This ducting design directs more water and a higher velocity into the propeller, thus improving the thrust produced. This designed is used by tugs and trawlers as it improves the bollard pull.

Question 12

How does ventilation trunking prevent the passage of smoke and flame?

Answer 12

A fusible links is used to close the damper when a set temperature is reached
A fire retardant steel gauze is used as a flame arrestor

Question 13

How does a ventilation trunk maintain the integrity of the bulkhead?

Answer 13

The ventilation ducting is lined with a steel sleeve with a thickness of 3mm. the ducting should be insulated as per the bulkhead.

Question 14

What is a watertight door?

Answer 14

A water tight door is designed to prevent water between watertight compartments while allowing passage of crew members. Water tight doors are designed to withstand a significant head pressure. Located below the bulkhead deck

Question 15

What is a weather-tight door?

Answer 15

A weather tight door is designed to prevent rain, spray and green seas from passage to the interior, however, allow passage of crew members. It can not withstand a head pressure, Located above the bulkhead deck, typically in the the superstructure.

Question 16

Water tight door regulations?

Answer 16

When closed remotely the visual and audible alarm will sound for 5-10seconds before closing
Will close in 20-40 seconds
Have a uniform closing speed
Audible alarm

Question 17

How are bilge keels fitted to prevent damage to the shell?

Answer 17

Do not protrude the moulded beam or draft
Use doubling plates to add structural strength
Scalloped to allow easy bending.

Question 18

Why are scuppers fitted near the superstructure whereas freeing ports are in the bulwarks?

Answer 18

Scuppers are designed to stop the accumulation of water around the superstructure to prevent corrosion. The freeing ports are designed to remove large amounts of water from the freeboard deck in the even of green seas

Question 19

Why are guardrails used on oil tankers?

Answer 19

To drain large amounts of green seas quickly as the freeboard is typically less than other ships
For cost purposes, Less material, less cost

Question 20

What is the unit for sound measurement?

Answer 20

Decibel (a) is the measurements of the intensity of sound pressure/energy in a unit area over a unit time, working on a logarithmic scale.

Question 21

How does a ship float

Answer 21

Any body wholly or partially immersed in a fluid experiences an upwards force equal to the weight of the fluid displaced

Any floating object displaces its own wait of fluid
Displacing enough water to counteract there weight