stress

Question 1

Hogging?

Answer 1

Ship is supported midships by wave but ends are unsupported

Question 2

Sagging?

Answer 2

Ship is supported at each end by crests of adjacent waves but is unsupported midships

Question 3

Racking?

Answer 3

External force on one side of ship will change the section so that the sides of ship aren’t perpindicular to the bottom of ship

Question 4

Describe B quality steel

Answer 4

• used in high stress areas
• crack resistant

Question 5

describe BX steel

Answer 5

• 18mm thick
• used in keels and rudder bridge assembly

Question 6

Describe D grade steel

Answer 6

• Mild steel with guaranteed toughness
• used in unstressed areas or areas not needing crack arresting

Question 7

Advantages of steel?

Answer 7

• Weldable
  strong
  ductile
  cheap

Question 8

Disadvantage of steel

Answer 8

• Magnetic
  heavy
  corrodes
  can fail

Question 9

Aluminium

Answer 9

• Good weight to strength ratio
  used where weight is important ie in superstructures
  can’t be used in for structual intergrity due to low melt temp

Question 10

Ships structure 3 categories

Answer 10

• Primary-main structual strength (hull,frames,main WT bulkheads)
• Secondary-WT integrity (does not contribute to structual strength)
• Minor-doesnt contribute to WT or structual strentgth

Question 11

How is the superstructre supported?

Answer 11

Transverse bulkheads

Question 12

Keel?

Answer 12

• runs along bottom fwd to aft
• Flat keels max strength at midships
• Vertical heel max strength of after cut up to resist sagging in dry dock

Question 13

Double bottom advantage

Answer 13

• Additional protection
  Contribute to longitudinal strength
  is a second hull
  used for counter flooding

Question 14

Inner bottom plating

Answer 14

• watertight deck fitted on top of longitudinal & transverse frames
• Maintains WT integrity in event of damage to outer bottom

Question 15

Purpose of watertight subdivision?

Answer 15

Divide buoyant volume of ship into smaller compartments, to preserve a buoyancy in event of hull damage
achieved by,
* main transverse bulkheads
* main longitudinal bulkheads
* WT bulkheads,decks & flats
* Double bottoms & tanks

Question 16

Main transverse bulkheads

Answer 16

• Stiffen ships structure
• withstand pressures of flood compartments
• reduce the effects of damage on the ship

Question 17

Collision bulkheads

Answer 17

Maintains WT integrity in event of damage to fwd of aft of ship

Question 18

Decks function as

Answer 18

• Horizontal strength
• With bulkheads form a WT subdivision
• Platforms & boundries of compartments

Question 19

Superstructure

Answer 19

• Contributes little to structural strength
• Is all structure above strength deck ( accom,hangar,bridge,funnel ect..)
• Supported by transverse bulkheads
• Aluminium made

Question 20

which part of the rudder bears the most load?

Answer 20

Lower part

Question 21

Shaft brackets

Answer 21

• Barrel,Arms & Palms
• bearing material is NF21 or ORKOT

Question 22

Corrosion caused by

Answer 22

• Oxidation (rusting)
• Electrolytic action (dissimilar metals)
• Chemical action-Acide attack from batteries
• Bacterial action-found in bilges & fuel tanks

Question 23

How is corrosion categorised?

Answer 23

• by depth & area
  Light=pitting of less than 1mm
  Medium=depth greater than 1mm but wastage less than 70% of plate thickness
  Heavy-wastage greater than 70% plate thickness

Question 24

Surveys done by?

Answer 24

• LLoyds register
• MCTA

Question 25

Guardrails defects?

Answer 25

* SIEZED COMPONENTS Cracked welds Corrosion Missin parts

Question 26

ladder maintenece?

Answer 26

* Security of fastenings Check for distortion Check backplate for security & noise Check hinges for security & noise