Stability

Question 1

What is the minimum information you would expect to have on your ship with regard to stability?

Answer 1

Within the stability book

Curves or tables of minimum operational metacentric height (GM)

Maximum permissible trim versus draft which ensures compliance with the intact and damage stability requirements where applicable

Alternatively corresponding curves or tables of the maximum allowable vertical centre of gravity (KG)

Instructions concerning the operation of cross flooding arrangements

Question 2

What is a lightweight survey

Answer 2

Taking an audit of all items that should be added, deducted or relocated on the ship at the time of inclination experiment so the observed condition can be adjusted to the true lightship condition.

Each item should be accurately located and weighed

Using the ships hydrostatic data, the freeboard, and sea water density, the lightship displacement and longditudinal centre of gravity can be obtained.

Question 3

Tugs and anchor handlers have specific info about their gear in their Stability Booklet such as

Answer 3

Maximum bollard pull, towing arrangement, pull points on the vessel, critical downflooding points, wires, quick release devices

Question 4

Vessels engaged in lifting operations have specific information within the stability booklet, like….

Answer 4

Maximum heeling moments for each direction of lift and counter ballast instructions, crane swl, boom radius, step by step operational plan

Question 5

Stability booklet information specifically for timber deck cargos

Answer 5

Must always have positive stability and stability calculated having regard for 25% water absorbtion and ice acretion (if applicable)

Maximum amount of deck cargo for lightest stowage

Master to
Cease loading if a list develops

Go to sea in upright condition
with adequate metecentric height
meets the required stability criteria

Question 6

How can you carry out stability calculations

Answer 6

The stability instrument. Its a computer software that calculates the heeling moments i.e. weights and there locations to give intact and damage stability information such as the CoG/B, GM, GZ, and area under the GZ is determined

Question 7

Who should test the stability instrument?

Answer 7

It is the responsibility of the master to check the accuracy of the software at the annual survey with a test condition

Question 8

What is statical stability?

Answer 8

Indicated by the righting lever curve

Generated from horizontal distance of CoB and CoG, creates the righting lever

Question 9

Purpose of the inclination experiment

Answer 9

To find KG in lightship condition