3.1 This test is to establish the craft performance
and accelerations experienced during cruise modes with no passenger
load or cargo load during the following conditions:
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.1 normal operation conditions are those in which
the craft will safely cruise at any heading while manually operated,
auto-pilot assisted operated or operated with any automatic control
system in normal mode; and
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.2 worst intended conditions, referred to in 1.4.48
of this Code, are those in which it should be possible to maintain
safe cruise without exceptional piloting skill. However, operations
at all headings relative to the wind and sea may not be possible.
For type of craft having a higher performance standard in non-displacement
mode, the performance and accelerations should also be established
at displacement mode during operation in the worst intended condition.
3.2 Operation levels, as defined in 3.1, should be established and documented
by full-scale tests in at least two relevant sea conditions and in
head, beam and following seas. Test period should be at least 15 min.
Model tests and mathematical simulations could be used to verify the
performance in the worst intended conditions.
Limits for normal operation condition should be documented by
measurements of craft speed, heading to the wave and interpolation
of measurements of maximum horizontal accelerations in accordance
with 2.4 of annex 3. Measurement of wave
height and period should be made to the maximum extent practicable.
Limits for worst intended condition should be documented by
measurements of craft speed, wave height and period, heading to the
wave and by root mean square (RMS) values of horizontal accelerations
in accordance with 2.4 of annex 3 and
of vertical accelerations close to the craft longitudinal centre of
gravity. RMS values could be used for extrapolation of peak values.
To obtain the expected peak values related to structural design load
and safety levels (1 per 5-min exceedance), multiply the RMS values
by 3.0 or
where:
|
N |
= |
is the number of successive amplitudes
within the relevant period. |
If not otherwise verified by model tests or by mathematical
calculations, it might be assumed a linear relation between wave height
and accelerations based on measurements in the two sea conditions.
Limits for worst intended condition should be documented both related
to passenger safety in accordance with 2.4 of annex
3 and related to the actual structural design load of the craft.
3.3 The tests and verification process should
document the limiting seas for safe operation of the craft:
-
.1 in normal operation at maximum operational
speed the accelerations should not exceed safety level 1 in annex 3 with an average of 1 per 5-min period.
The craft operating manual should include detailed description of
the effects of speed reduction or change of heading to the waves in
order to prevent exceedance;
-
.2 in the worst intended conditions, with reduced
speed as necessary, the accelerations should not exceed safety level
2 in annex 3 with an average of 1 per
5-min period, nor should any other craft characteristic motion as
pitch, roll and yaw exceed levels that could impede the safety of
passengers. In worst intended conditions, with reduced speed as necessary,
craft should be safely manoeuvrable and provide adequate stability
in order that the craft can continue safe operation to the nearest
place of refuge, provided caution is exercised in handling. Passengers
should be required to be seated when safety level 1 in annex 3 is exceeded; and
-
.3 within the actual structural design load for
the craft, with reduced speed and change of heading, as necessary.
3.4 Turning and manoeuvrability
The craft should be safely controllable and manoeuvrable during:
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.1 hull-borne operation;
-
.2 operation in non-displacement mode;
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.3 take-off, landing;
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.4 any intermediate or transition modes, as applicable;
and
-
.5 berthing operations, as applicable.