Università degli Studi di Napoli “Federico II”, which has the following dimensions:
Length Breadth
Water Depth
136.0 m 9.0 m 4.5 m
In all the test cases the towing force was horizontal and applied to the catamaran centreplane. The application point of the towing force was placed 100 mm forward the forward perpendicular and 554 mm from the base line for C932 and 396 mm for C925.
Total resistance and running trim were measured for each run. Resistance measurements were made with a 50 kg load cell (accuracy: 0.003 kg). The running trim was measured by a servo inclinometer (accuracy 0.01 degrees).
Both the models were not fitted with turbulence stimulators. The Reynolds number ranges were:
C932: C925:
3.0 × 106 ÷ 11.0 × 106 3.0 × 106 ÷ 9.0 × 106.
All the resistance coefficients have been calculated considering the static wetted surface.
Viscous blockage effects and shallow water effects were found to be negligible, hence, no corrections were applied to the results.
4. SYMMETRIC CATAMARANS
From the experimental towing test results, for both the models, the residuary coefficients, CR, and the total interference factors, IT, have been calculated.
4.1 RESIDUARY RESISTANCE
For both the models the experimental measurements of the resistance tests and the fair curves are presented as CR versus Fn graphs. Data are plotted for demihull and for all catamaran configurations.
10 12 14
0 2 4 6 8
CR 103 EXP. DATA
10 12 14 16 18 20
0 2 4 6 8
CR 103 L/1/3 = 4.66 L/1/3 = 5.08 L/1/3 = 5.74
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Fn
Figure 5: [C 932 – S/L = 0.24]
10 12 14 16 18 20
0 2 4 6 8
CR 103 EXP. DATA
EXP. DATA
L/1/3 = 4.66 L/1/3 = 5.08 L/1/3 = 5.74
0.10.2 0.30.4 0.50.6 Figure 6: [C 932 – S/L = 0.27]
10 12 14 16 18 20
0 2 4 6 8
CR 103 L/1/3 = 4.66
0.70.8 0.91.0 Fn
EXP. DATA
L/1/3 = 5.08 L/1/3 = 5.74
0.10.2 0.30.4 0.50.6 Figure 7: [C 932 – S/L = 0.30]
L/1/3 = 5.87 L/1/3 = 6.39
L/1/3 = 7.23
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Fn
Figure 4: [C 932 – Demihull]
10 12 14 16 18 20
0 2 4 6 8
0.10.2 Figure 8: [C 932 – S/L = 0.33] CR 103
0.70.8 0.91.0 Fn
EXP. DATA
L/1/3 = 4.66 L/1/3 = 5.08 L/1/3 = 5.74 0.30.4 0.50.6
0.70.8 0.91.0 Fn
©2007: Royal Institution of Naval Architects
B-25
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