2016 Course

Awareness-Raising Course on Fishing Vessel Stability


Stability is one of the most important factors in every fishing vessel’s overall safety. It is estimated that, in some countries, the capsizing of fishing vessels accounts for more than 50% of the fatalities. Without reducing the importance of life-saving equipment, every possible means should be used to prevent the capsizing of a vessel as the vessel itself is the best survival craft.

The main objective of this course is to raise awareness on fishing vessel stability among fishing communities and thereby contribute to improve stability of the vessels and safe practice.

This course consist of:

  • A 3-Day Training of Trainers Course, which objective is to train future trainers providing them with sufficient capabilities to deliver the Half-Day Awareness-raising Course.
  • A Half-Day Awareness-raising Course on Fishing Vessel Stability, which objective is to raise awareness among fishermen, their families, local authorities and other stakeholders.

The instructors of the 3-Day Training of Trainers Course should preferably be a naval architect. Alternatively, the instructor could also be a marine engineer, or a person with sufficient expertise in naval architectural matters.

It is recommended that the Half-Day Awareness-raising Course be led by two trainers, one with theoretical and another with practical background, such as a naval architect and a marine administration worker with expertise in fishing vessel stability matters.

Material required

The material required to develop the courses comprises:

  • Two Power-Point presentations, one for the "Three-day Training of Trainers Course" and one for the "Half-day Course for Fishermen";
  • FAO Stability of Fishing Vessels Video (Part 1 and Part 2);
  • FAO Stability Booklet, to be used as handout material for participants for both courses;
  • Tank and model for demonstrations of stability scenarios, to be constructed according to the drawing plans.

Nevertheless, all the material can be modified accordingly to the countries or region’s needs.

In order to prepare the courses, approximately 2h are needed to fill up the water tank and prepare the computer equipment.


3-Day Training of Trainers Course


The objectives of the 3-Day Course are that trainees should be able to demonstrate and explain all aspects governing the stability of fishing vessels and to conduct practical demonstrations with some theory on fishing vessel stability.


The Course contents comprises, firstly, basic definitions of the main dimensions, naval terminology as well as a brief description of the hull forms and coefficients and the use of Simpson’s rules to estimate areas. Continuing with this first part, the hydrostatic particulars, the equilibrium conditions and the initial and large angle stability concepts are introduced as well as the effects of moving or suspending weights and the free surface effects. Finally, some dangerous situations and solutions to avoid them are described. At the end of the course, some indications will be given to perform the half-day awareness-raising course.

The recommended lesson plan is shown below.

Half-Day Awareness-raising Course on Fishing Vessel Stability


The purpose of the Half-day Course for Fishermen is to improve the awareness on stability of vessels among fishermen and to introduce some basic principles on what fishing vessels crews can do to maintain an adequate safety on their vessels.

The final aim is to make it useful not only to fishermen but also to their families, fishing vessel owners, boat designers, boat builders, training institutions, insurance companies, competent authorities and others who may have an interest in the safety of fishing vessels and fishermen.


The Course contents comprises basic definitions of the fishing vessel dimensions and terminology and a brief description of the equilibrium conditions and the main stability parameters to take into account. The weight movement and free surface effects will be introduced and some common dangerous situations will be explained.

The recommended lesson plan is shown below.


Lesson plan for the "3-Day Training of Trainers Course"

DAY – 1


Registration for the course


Introduction to the course with aim and objectives of the course


Discuss the awareness of the fishing vessel and stability by the trainees with respect to their answers




Main dimensions and terminology

  • Illustrate the terms with a boat model


Definition of centre of buoyancy

  • Demonstrate that the centre of buoyancy changes with the draft
  • Demonstrate that centre of buoyancy oscillate with rolling of the ships
  • Demonstrate the movement of centre of buoyancy as a vessel gradually incline to one direction
  • Effect of beam to the distance that centre of buoyancy can move


Definition of centre of gravity

  • Define the centre of gravity
  • Illustrate the centre of gravity of a light vessel
  • Illustrate that the centre of gravity of a loaded vessel depends on the distribution (location) of loads
  • Demonstrate the above phenomena using the boat model




Hull form and lines plan

  • Explain with a set of lines drawings (profile plan, waterline plan and body plan)
  • Offset tables and use of offset tables
  • Explain how to get the half ordinates values


Simpson’s Rules and estimation of areas

  • Use of handouts
  • Measure the offsets of a particular cross section or waterplane and use the Simpson’s First rule to estimate the area
  • Aware that volume can be found by integration of cross-sectional areas or waterplane areas



3.15- 3.50

Hull form coefficients (CB, CP, CW and CM)

  • Use of CB to estimate the volume when dimensions are known
  • Vessel dimensions and relationships of CP, CW and CM


Definition of initial metacentre

  • Define the initial metacentre using the presentation figures

4.20- 4.30

Recapture of the day



DAY – 2

9.00 -9.45

Hydrostatic particulars and their estimations

  • Hydrostatics curves and tables
  • Use of hydrostatic particulars to read displacement, KM, etc.




Initial Stability and three equilibrium conditions

  • Explain three different equilibrium conditions

Stable, Unstable and Neutral with respect to the initial GM

  • Demonstrate with a model the above three conditions
  • GM estimation and how to improve it


Tender and stiff vessel

  • Explain the relationship between metacentric height and rolling period
  • Define the stiff vessel and tender vessel
  • Demonstrate the stiff vessel and tender vessel using the model


Effect of weight movement on G and initial stability

  • Effect of vertical, transverse and general movement of a weight
  • Demonstrate the above effects using the model and relate this to the stowage of the catch on deck
  • Effect of suspended weight
  • Demonstrate the suspended weight effect using the model and relate these to loading/unloading handling of fish
  • Use the weight movement concept for inclining test



1.30- 2.30

Video Stability FAO – Part 1


Effect of loading/unloading a weight on G and initial stability

  • Effect of loading/unloading at the centerplane
  • Effect of loading/unloading at a general point
  • Effect of loading/unloading using a crane/derrick
  • Demonstrate the above using model and relate these to handling of fish

3.15- 3.30



Effect of free liquid

  • Demonstrate the effect of liquid in tanks to the metacentric height and rolling period using the model
  • Demonstrate that the longitudinal subdivision would reduce the free surface effect using the model
  • Relate above to ingress of water on to the deck and the importance of freeing ports


Recapture of the day



DAY – 3


Stability at large angles of heel and GZ

  • Define the righting lever (GZ) and it’s relation with the position of G
  • Explain why metacentre cannot be further used to study the stability at large angle of heel
  • Explain the movement of centre of buoyancy with the angle of inclination of the vessel and the relation of it with the variation of GZ with the heel angle
  • Explain the calculation of the GZ at small and large angles of heel
  • Define the stability curve and its main parameters
  • Demonstrate the feeling of the righting moment using a model

9.45 -10.30

Assessment of intact stability and stability criteria

  • Perform the calculation of the Δ, KG, GM and GZ curve
  • Explain why criteria are needed to assess the minimum stability
  • Notes on basic criterion to be tested




Effect of vessel’s parameter on GZ

  • Effect of beam on GZ
  • Effect of freeboard on GZ

Effect of weight movement on GZ

  • Rise of vertical centre of gravity on GZ and subsequent loll
  • Transverse shift of centre of gravity on GZ and subsequent list
  • Demonstrate using a model
  • Explain the changes in the stability during a voyage and the meaning of the Stability Notes for small vessels


Watertight and Weathertight Integrity

  • Explain the purpose of watertight hull, watertight subdivisions and weathertight closing devices
  • Precautions to be taken to maintain watertight and weathertight integrity
  • Explain the importance of the buoyancy compartments for undecked vessels



1.30- 2.30

Video Stability FAO - Part 2

2.30- 3.15

Some dangerous situations

  • Aware of dangerous situations
  • Measures to be taken to avoid such situations
  • Use of the model to demonstrate them




Preparation of trainee for "Half-day Course for Fishermen"

  • Identify the relevant notes, videos and demonstration to be performed
  • Identify the ways of imparting the knowledge of trainers to fishermen


Closing session



Lesson Plan for the "Half-Day Awareness-Raising Course on Fishing Vessel Stability"


Introduction of the course


Video Stability FAO - Part 1 and Part 2




Definition of vessel’s dimension and terminology:

  • Main dimensions:
  • Length over all, length between perpendiculars, beam, depth to main deck, draught, freeboard
  • Definitions and terminology:
  • Volume of displacement, displacement, light ship weight, dead weight, list, heel, loll, trim
  • Centre of gravity
  • Centre of buoyancy


(5 min/item approx.)

Definition of metacentre

Definition of GM

Definition of three equilibrium conditions

How to improve GM

Tender and stiff vessels

Effects of weight movements and suspended weight

Effect of free liquid and how to reduce its effect:

  • Free liquid in tanks
  • Water on deck
  • Stowage of catch

Watertight and weathertight integrity:

  • Definition of watertight and weathertight
  • Precautions to be taken
  • Buoyancy compartments for small vessels


Dangerous situations:

  • Enclosed superstructure and means of closing
  • Security of heavy material
  • Stowage of the catch
  • Overweight on deck
  • Effect of fishing gear on the stability
  • Free surface effects
  • Freeboard and loading conditions
  • Following and quartering seas
  • Crossing sand bars and beach landings
  • Alterations to vessels


Demonstration of the model and discussion

(the effect of low and high weights, overweight, suspended weight, free surface effects and the effects of a longitudinal bulkhead, loll, rolling, importance of securing of heavy weights, etc.)

last updated:  Sunday, September 23, 2018