2.2 Construction

 The model should comply with the following:

• .1 be capable of operating in both displacement mode and where appropriate in the non-displacement mode at a running attitude (trim and sinkage) appropriate to the full scale craft;

• .2 any lift devices (e.g., fans, foils, flaps, flexible seals, wings, etc.) should generate forces, pressures and volumetric flows resulting in the same running attitude in calm water, as specified above, ensuring a bow height accuracy within 5%. Actively controlled stabilizing or ride-control devices should be assumed to be in a fixed pre-set or passive mode;

• .3 the hull should be suitably thin (0.01L_model with a minimum of 2 mm is recommended) in floodable spaces;

• .4 be equipped with all main design features such as watertight bulkheads, air escapes, freeing ports, access trunks, etc corresponding to the full scale vehicle spaces, and modelled properly to represent the real situation as far as practicable;

• .5 be constructed with superstructures to the extent needed to ensure a realistic response in waves;

• .6 be suitably constructed to permit monitoring of the interior of the floodable spaces, using video cameras;

• .7 be equipped with external appendages such as bilge keels, spray rails, lift devices or fendering as may reasonably be expected to influence the results of the tests;

• .8 be provided with a bow aperture to accurately model the full scale craft after the bow loading door(s) may have been lost, special attention being paid to the freeboard at the lowest point;

• .9 be equipped with fast-closing watertight shutters to the bow aperture(s) and any drainage openings that can be remotely opened and closed at the beginning and end of the test period during each run;

• .10 prior to ballasting, the model should be equipped with all the necessary instrumentation; and

• .11 freeing ports and other means of drainage should be closed at all times during the tests.

 The reduction of permeability of the vehicle spaces due to the presence of cargo should not be represented.

  2.2.3.1 The mass of the model after ballasting to the directly scaled design waterline should be within ±1% of that representing the full scale craft.

  2.2.3.2 The longitudinal centre-of-gravity after ballasting to the directly scaled design waterline should result in a static trim attitude within 0.2° of that representing the full scale craft.

  2.2.3.3 The volume of the vehicle spaces to the first downflooding opening derived when the craft is at the designed trim attitude should be within ±2% of that representing the full scale craft. Where open vehicle spaces are modelled, the volume should be measured up to the level at which water might first begin to spill out, or alternatively the deck area should be within ± 2% of that representing the full scale craft (commensurate with hull thickness as specified in 2.2.1.3).

  2.2.3.4 The freeboard from the directly scaled design waterline (at zero speed) to the lowest point of the bow loading opening should be within +0 to -1% of that representing the full scale craft.