CMI Vessel Stability & Structural Integrity

Question 1

What does metacentric height (GM) measure in vessel stability analysis?

Accepted Answer

The distance between the center of gravity (G) and the metacenter (M)

Answer

The distance between the keel and the waterline at midship

Answer

The righting moment acting on a stationary vessel

Answer

The height of the center of buoyancy above the keel

Question 2

How does a vessel in a 'loll' condition differ from one with a 'list'?

Accepted Answer

Loll results from negative GM; list results from off-center weight or asymmetric loading

Answer

Loll results from off-center weight placement; list results from negative GM

Answer

Both loll and list are caused by negative metacentric height

Answer

List results from free surface effect; loll results exclusively from cargo shift

Question 3

What does the GZ curve (righting lever curve) represent in a vessel's stability diagram?

Accepted Answer

The righting lever (arm) distance at various angles of heel

Answer

The angle of heel under wind loading at various sea states

Answer

The metacentric height variation across different drafts

Answer

The buoyancy force distribution along the hull length

Question 4

Under the IMO Intact Stability Code (IS Code 2008), what is the minimum required area under the GZ curve from 0° to 40° for passenger vessels?

Accepted Answer

0.090 m·rad

Answer

0.030 m·rad

Answer

0.055 m·rad

Answer

0.120 m·rad

Question 5

What is the 'free surface effect' in vessel stability?

Accepted Answer

The reduction in effective GM caused by transverse movement of liquid in partially filled (slack) tanks

Answer

The stabilizing contribution of ballast water in fully loaded tanks

Answer

The effect of wave action on a vessel's external waterplane area

Answer

The stability benefit derived from increased waterplane area at larger heel angles

Question 6

When investigating a capsizing incident, what should a CMI investigator assess as the first priority?

Accepted Answer

Stability booklet and the actual loading condition at the time of the incident

Answer

Engine room maintenance logs and fuel consumption records

Answer

Navigation charts, GPS track, and voyage plan

Answer

Crew certification records and watch schedule

Question 7

The International Load Line Convention (Plimsoll marks) primarily regulates what aspect of vessel safety?

Accepted Answer

Minimum freeboard to ensure adequate buoyancy and stability reserves in different zones and seasons

Answer

Maximum allowable crew complement by vessel tonnage class

Answer

Required liferaft capacity relative to persons on board

Answer

Minimum hull plating thickness by sea area