The IT factor curves of both models are shown for each displacement and S/L.
0.8 1.0 1.2 1.4 1.6
IT
S/L = 0.24 S/L = 0.27
S/L = 0.30 S/L = 0.33 S/L = 0.36
S/L = 0.41
1.6 IT 1.4 1.2 1.0 Fn 0.8
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 Fn
Figure 19: [C 932 – L/1/3 = 5.74]
0.8 1.0 1.2 1.4 1.6
IT
S/L = 0.24 S/L = 0.27
S/L = 0.30
S/L = 0.33 S/L = 0.36 S/L = 0.41
0.1 0.2 0.3 0.4 Figure 23: [C 925 – L/1/3 = 4.66]
Examining the IT factor curves, it is possible to note: for Fn < 0.35 the curves present undulations and it is not
possible dependence of IT from displacement and S/L;
around Fn = 0.35 - 0.40, IT is smaller than one for higher S/L ratio;
for Fn > 0.7 the IT curves converge to the unit.
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 Fn
Figure 20: [C 932 – L/1/3 = 5.08]
0.8 1.0 1.2 1.4 1.6
IT
S/L = 0.24 S/L = 0.27 S/L = 0.30
S/L = 0.33 S/L = 0.36
S/L = 0.41
The remarkable differences of the IT values for different configurations makes it difficult to evaluate the performance of a specific catamaran by the interference factors of other configurations (displacement or S/L).
5. STAGGERED CATAMARANS
In this paragraph experimental towing test results of the staggered catamaran configurations of both models are reported as CR, trim, and IT.
5.1 RESIDUARY RESISTANCE AND TRIM
In the following figures the experimental data and the fair curves are presented. It is possible to note that
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 Fn
Figure 21: [C 932 – L/1/3 = 4.66]
0.8 1.0 1.2 1.4 1.6
0.1 IT
S/L = 0.24 S/L = 0.30
S/L = 0.36
reducing L/1/3, curve undulations and CR values increase. Observing the staggered
catamaran
10 12 14 16
Fn 0.2 0.3 0.4 Figure 22: [C 925 – L/1/3 = 4.92] B-28 0.5 0.6 0.7
0 2 4 6 8
CR ×103 EXP. DATA L/1/3 = 4.66
resistance coefficients have remarkable increasing the longitudinal stagger.
diagrams, the reductions
0.5 0.6 0.7
S/L = 0.24 S/L = 0.30 S/L = 0.36
to identify a law describing the
L/1/3 = 5.74
0.25 0.30 0.35 0.40 0.45 0.50 0.55 Fn
Figure 24: [C 932 – Stagger 6 % LWL] ©2007: Royal Institution of Naval Architects
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