CMI Vessel Stability & Structural Integrity 2

Question 1

Stress corrosion cracking in marine structural steel most commonly occurs when:

Accepted Answer

Sustained tensile stress combines simultaneously with exposure to a corrosive environment

Answer

Low-cycle fatigue from wave-induced bending exceeds the material's endurance limit

Answer

Thermal cycling from engine room heat gradients causes repeated expansion and contraction

Answer

Galvanic coupling between dissimilar metals accelerates electrochemical attack

Question 2

What is the standard survey interval used by classification societies to maintain a vessel's class notation?

Accepted Answer

Annual surveys combined with a special survey (renewal survey) every 4–5 years

Answer

A comprehensive survey every 10 years with owner-reported inspections between

Answer

A single survey every 2.5 years covering all systems simultaneously

Answer

Survey intervals determined solely by the vessel's age and flag state requirements

Question 3

In marine structural investigation, 'wasting' refers to which condition?

Accepted Answer

Reduction in metal plate or member thickness caused by corrosion or erosion

Answer

Improper discharge of oily bilge water in a protected marine area

Answer

Progressive fatigue cracking of structural members under cyclic loading

Answer

Deformation of structural framing from grounding or allision loads

Question 4

Fatigue cracks in a vessel's hull structure preferentially initiate at:

Accepted Answer

Stress concentration points such as cutouts, bracket toes, and weld terminations

Answer

Areas of maximum plate thickness where stress is lowest

Answer

Flat plate panels located far from edges and structural discontinuities

Answer

Regions protected by cathodic protection systems and coating

Question 5

In vessel structural terminology, 'hogging' is best described as:

Accepted Answer

The midship section of the hull bending upward relative to the bow and stern

Answer

The midship section of the hull deflecting downward relative to the bow and stern

Answer

Excessive rolling caused by wave period resonance with the vessel's natural roll period

Answer

Progressive flooding of forward compartments that trims the vessel by the head

Question 6

During a marine structural failure investigation, which categories of documentary evidence should be collected as the highest priority?

Accepted Answer

Pre-existing defects, repair history, maintenance logs, and operational loading patterns

Answer

Crew social media posts and personal communication records

Answer

Only the most recent annual classification survey report

Answer

Incident records from structurally similar sister vessels in the same fleet

Question 7

Compared to conventional mild steel, high-tensile steel (HTS) used in modern ship construction:

Accepted Answer

Allows reduced plate thickness due to higher yield strength but requires careful welding procedures because of greater sensitivity to weld defects

Answer

Has lower yield strength but superior inherent corrosion resistance

Answer

Is used exclusively for above-waterline superstructure and deck houses

Answer

Eliminates the requirement for cathodic protection and anti-corrosion coating systems