Textos de Apoio (pdf)

ITTC – Recommended
7.5-04
-01-01.1
Procedures and Guidelines Page 8 of 10
Full Scale Measurements
Speed and Power Trials
Preparation and Conduct of
Speed/Power Trials
Effective Date
2005
Revision
03
In accordance with ISO 15016 the following,
general recommendations can be given:
4.5.1 Wind:
Wind speed and direction shall be measured
as relative wind; continuous recording of relative
wind during each run is recommended.
Care has to be taken whether the data derived
from the wind indicator are reliable; checks,
such as parallel measurements with a portable
instrument, comparison of the data received
from the wind indicator with wind speeds and
directions received from local weather stations
sufficiently close to the actual position of the
ship or, if possible, calibration of the wind indicator
(taking into consideration the effects of
boundary layers of the superstructure on the
measured values) in a wind tunnel are recommended.
It is suggested that wind force during the
trial runs under no conditions should be higher
than
• Beaufort 6 for ships with lengths equal
or exceeding 100m and
• Beaufort 5 for ships shorter than 100m.
4.5.2 Sea State:
If possible, instruments such as buoys or instruments
onboard ships (e.g. seaway analysis
radar) should be used to determine the wave
height, wave period and direction of seas and
swell. Considering usual practice the wave
heights may be determined from observations
by multiple, experienced observers, including
the nautical staff on board.
During the trial runs the total wave height
(double amplitude), which allows for the wave
heights of seas and swell (see ISO 15016),
should not exceed
• 3m for ships of 100m length and more
and
• 1,5m for ships with lengths smaller than
100m
4.5.3 Current:
Current speed and direction shall be obtained
either as part of the evaluation of run
and counter-run of each double run, by direct
measurement with a current gauge buoy or by
use of nautical charts of the respective trial area.
It is recommended to compare measured data
with those included on the nautical charts.
4.6 Trial Conduct:
All speed trials shall be carried out using
double runs, i.e. each run is followed by a return
run in the opposite direction, performed
with the same engine settings.
The number of such double runs should not
be less than three. This three runs should be at
different engine settings.
The time necessary for a speed run depends
on the ship’s speed, size and power. Steady
state conditions should be achieved before the
speed runs start. It is recommended that the
time of one run should be as long as possible
but should at least be 10 min.
The ideal path of a ship in a typical
speed/power maneuver is shown in Figure 1: