The Hamburg Ship Model Basin

Setting the Standard in Ship Optimisation

Video 100 years

Tests in the Ice Tank

Ice model testing in HSVA’s large ice tank is the main expertise of the HSVA Arctic Technology department. Several kinds of ships and structures can be tested in all kinds of sea ice features.

 

Frequently tested vessel types:

  • Ice going merchant ships (tanker, gas tanker, bulk carrier, heavy lift carrier, general cargo vessel, etc.)
  • Icebreakers
  • Ice breaking research vessels
  • Ice breaking service ships (offshore supply, anchor handler, emergency response)
  • Ice breaking inland waterway vessels

 

Frequently tested fixed structures:

  • Loading tower and terminal
  • Jacket structure
  • wind generator foundations
  • Berthing structures
  • Multi-legged GBS
  • Artificial islands
  • Mitigation and protection structures

 

Frequently tested floating structures:

  • Ship shape floaters like Drill Ship, FPSO FPU etc.
  • Semi submersibles
  • Buoy shape floaters
  • Spar buoy

 

Depending on the project demand numerous different set-ups are available. Each project deserves a unique solution regarding set-up and investigations, nevertheless there are certain kinds of test setups and ice property investigations that are available by default.

 

High frequently performed tests are:

 

Frequently tested ice properties:

  • General
    • Ice temperature
    • Ice salinity
    • Ice density
  • Level ice
    • Ice thickness
    • Ice flexural strength
    • Ice bending strength
    • Ice Young’s modulus
    • Ice crushing strength (by indenter)
    • Level ice uniaxial compressive strength
  • Floe ice, natural and managed
    • Floe size
    • Ice concentration (coverage)
    • Floe size distribution
  • Brash ice
    • Brash ice thickness
  • Rubble field
    • Rubble field thickness
    • Rubble size
  • Ridge
    • Ridge profile
    • Punch test
    • Freeze bond

 

Apart from the above listed testing procedures we are always creative in finding new solutions for test set-ups and ice property determination methods. If you have requirements regarding property testing that are not covered by the above listed tests, do not hesitate to contact us for an individual solution.

Towed propulsion

During the towed propulsion test the model is connected to the service carriage, which is pushed by the main carriage, via a rigid rod that itself is attached to a load cell at the bows of the model. After being accelerated the model is towed at constant speed. The propeller rpm is changed in four steps from near idling condition through a value close to the self-propulsion point up to a value well above the self-propulsion condition. Both, the thrust of propellers and the coupling force is measured and therefore the actual propulsion point for the given speed can be determined throughout interpolation from linear correlation between thrust and pull force. The resistance can be read from the intersection point of the same curve with the axis of ordinates.

Tests in the ice tank 01

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Free running propulsion and manoeuvering

For the free running test model and carriage are connected only by the cables, which are needed to transfer electrical power into and the measuring signals out of the model. Cables are kept above the model during manoeuvering operations in order to avoid any force application. The model itself is self-propelled while the rpm of each propeller may be remote controlled by throttles from the carriage. For manoeuvering tests, the rudder or azimuth angle can also be controlled by the operator. A motion capture system is used to detect the rigid body motions in all six degrees of freedom. The system uses four cameras installed at the main carriage to detect markers which are located at different positions on the model. Thereby the relative motion between carriage and model may be recorded during the free running tests.

Tests in the ice tank 02

Measured quantities during towed and free running propulsion test:

  • Carriage / model speed
  • Tow force (only towed condition)
  • Propeller revolution
  • Propeller and/or system thrust
  • Shaft torque
  • Rudder / azimuth angle
  • Surge
  • Sway
  • Heave
  • Roll
  • Pitch
  • Yaw

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Station keeping

                                                                                                                                                                                                                                                

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Moored Floating Structures

Moored floating structures can be tested with different test setups in the large model basin of the HSVA. Due to the limited space the mooring system is mostly modelled as a truncated system using either a dry or wet mooring set-up. The mooring characteristic in both setups is simulated by a defined combination of springs and stopper lines.

The wet mooring arrangement is mounted on a submerged framework below the ice sheet which is connected to the main carriage. As the model is connected via stiff lines to the spring packages the model is pushed through the ice. Thereby the ice drift is simulated in reverse by moving the model and not the ice.

The dry mooring system has a similar setup but the spring package is mounted on a frame which is connected to the Y- axis of the carriage. The advantage is that any ice drift direction can be simulated with this setup.

 

Tests in the ice tank 03

Tests in the ice tank 04

 

If the floater is equipped with an additional DP system for heading keeping this can be modelled as well by combining the mooring setup with a DP system operating the thrusters. Due to the open architecture the DP-System can either be the HSVA in-house DP or any other operated by for instance the DP system supplier of the actual vessel.

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Dynamic Positioning

HSVA owns a DP system designed for DP model testing in open and ice covered water. The DP system can be adjusted to a certain vessel and allows for several kinds of DP tests in model ice. The DP system is a result of a European research project DYPIC – Dynamic Positioning in Ice. It has proved its performance in tens of runs and can either be used in a setup where the ice is pushed through the resting vessel or where the vessel keeps its position relative to the ice tanks main carriage while the carriage moves along the basin.

Tests in the ice tank 05

Tests in the ice tank 06

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Fixed mode testing

Regardless of the type each model can be tested in fixed mode. This means the models motion is blocked in a number of degrees of freedom. This can be partially e.g. only certain directions of motion are blocked or completely – in this case all six degrees of freedom are blocked. Ice induced vibrations can be investigated in a fixed mode where the model is rigidly connected to the basin floor and only motions in one or two directions is allowed. Ice loads on a vessel may be determined in a fixed setup where the vessel is rigidly connected to the main carriage and pushed through the ice. A special rotation platform allows testing the subject, vessel or structure, under certain oblique angles. In all cases forces in three axes and moments around these axes are determined by means of a six-component-scale. In addition to the forces accelerations, velocities and movements of the structure / vessel will be measured.

Tests in the ice tank 07

Tests in the ice tank 08

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