ERDC/CHL CHETN- IX-7
December 2001
Table 4
Summary of Wave Parameters Barbers Point Harbor, HI
Target for Gage 4
Measured at Gage 4
Ship
Date
In / Out
Draft, m
Signal
Hm0, m
Tp, sec
Hm0, m
Tp, sec
DDU612
0.40
6.4
0.53
4.0
21-May
IN
9.52
Atoyac
DDU622
0.39
15.1
0.53
4.1
DDU712
0.32
9.5
0.30
9.6
25-May
OUT
5.61
Atoyac
DDU722
0.30
5.3
0.30
5.4
DDU312
0.54
6.2
0.45
6.1
18-May
IN
6.01
Carla A. Hills
DDU322
0.46
6.4
0.45
6.4
DDU412
0.58
6.6
0.75
5.4
19-May
OUT
8.18
Carla A. Hills
DDU422
0.58
6.7
0.65
6.8
DDU112
0.43
5.4
0.38
5.5
14-May
IN
9.70
Port Catherine
DDU122
0.47
17.1
0.53
5.4
16-May
OUT
6.63
DDU212
0.42
12.8
0.45
12.2
Port Catherine
DDU512
0.41
6.0
0.45
6.0
20-May
IN
5.36
World Utility
DDU522
0.43
5.7
0.45
5.7
DDU412
0.58
6.6
0.75
5.4
30-May
OUT
10.84
World Utility
DDU422
0.58
6.7
0.65
6.8
Testing Procedure: For each wave case, two runs (i.e., one repeat) were made for each
inbound and outbound transit at two different vessel speeds and ship drafts. A slow and fast
vessel speed was selected to bracket the range of possible ship speeds for inbound and outbound
transits for all the ships. These speeds were calibrated with a series of speed trials. A quadratic,
least squares fit was calculated to predict the ship speed as a function of the tachometer setting
on the remote control. The assumption made was that the ship track was straight for all runs. A
light ship and a fully-loaded draft were tested for each ship transit. Typically, eight runs (i.e., 2
runs x 2 speeds x 2 transits) were made for each wave condition and ship draft.
Inshore and offshore start/stop lines were located across the entrance channel for measuring ship
motions using the MOTAN system. The inshore start/stop line was located near the shoreline at
Sta 3430 and the offshore line near Sta 610. The beginning and ending times for each transit
were recorded as the model ship crossed these start/stop lines. For inbound transits, the ship's
stern was used as the reference to insure that the ship was completely within the flat part of the
entrance channel. Similarly, for the outbound transits, the ship bow was used. The ship speed
was also calculated by dividing the distance between these start/stop lines (858.4 m prototype
units) by the travel time since the vessel speed was nearly constant during each transit. The two
different methods of calculating ship speed were compared and the latter method was selected as
the most accurate.
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