Deep Water Towing Tank Seakeeping and Manoeuvring Basin
Services & Products Ocean Engineering


Theoretical and experimental prediction of ship manoeuvring qualities

 

Calculations on ship manoeuvrability

  • Procedure for evaluation of curvilinear motion of transport ships in calm water
    For solving the system of non-linear differential equations of motion, a numerical method based on circulation separation theory is used. Trajectory of ship CG and kinematic parameters of steered motion are estimated.
  • Procedure for evaluation of steering qualities of cargo and passenger ships for inland and river-sea navigation
    Regulatory manoeuvring characteristics such as turning ability, course keeping ability, course stability under wind action, yaw checking, etc., are subject to estimation.
  • Simulation of manoeuvring qualities based on PMM tests
    An extended dynamical model of the "ship-control apparatus-propulsor" system is used to simulate, at given initial conditions, standard maneuvers such as turning, zig-zag and spiral, as well as system reaction in operational conditions. TOP


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Ship manoeuvring model tests

Standard free-running model manoeuvring tests
The free-running model tests are performed in BSHC manoeuvring and seakeeping basin, in accordance with standard ITTC techniques and IMO requirements.


Rudder stock moment and forces measurements

The hydrodynamic forces and moment acting on the rudder are predicted at towing the model in straight direction ahead or astern in deep water tank, at different rudder angles up to the maximal requested value.


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PMM captive model tests

Type of mechanism
  Large-amplitude horizontal PMM
Range of mechanism kinematics
  Sway/Surge mode
    - amplitude ±1.0 m
    - nondimensional acceleration from 0.0 to 0.5 [-]
    - frequency from 0.01 to 0.2 Hz
  Yawing mode
    - amplitude ± 35°
    - nondimentional velocity from 0.0 to 1.0 [-]
    - static drift angle ± 30°
    - frequency from 0.01 to 0.2 Hz
Model size up to 5 tons

 

 

Standard testing techniques and analysis methods are used for conducting detailed design and evaluation studies on the directional stability and control characteristics of steered vehicles at different operational regimes, including:
• Reference PMM tests conducted at the ship propulsion point with fully appended model for analysis of inherent directional stability and control characteristics.
• Standard PMM tests (including overload and underload PMM tests) to provide the complete set of hydrodynamic coefficients (mathematical model) required for computer simulation studies to evaluate the full range of manoeuvring characteristics of the ship.
• Bare-hull PMM tests to provide a basis for rudder design.

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Last updated 29 August 2014   

   
Bulgarian Academy of Sciences