In order to make the database of the hydrodynamic derivatives and coefficients for fishing vessels, hydrodynamic forces and moments are measured with several fishing vessels. The principal particulars of these ship models are listed in Table 1.

 Ship models A, B and C are the fisheries research vessels with stem trawl [5], and D and E [1] are the typical Japanese stern trawlers. Model F is the recent wide beam stern trawler in Northern Europe, and has a flapped rudder.

　

　

 The hydrodynamic derivatives and coefficients in the mathematical model can be obtained by captive model tests such as CMT (Circular Motion Test), oblique towing tests and rudder tests. Measured hydrodynamic force coefficients are shown in Fig. 3 - Fig.6 with ship model E as an example.

  Hull force and moment coefficients: XH, YH and NH are measured by CMT. Forces and moment are made non-dimensional by (p/2) LdU² (p/2) L²dU² respectively and plotted in Fig.3 against drift angle. The curves in these figures show the identified characteristics using eq. (3) with the parameter of r'. The hydrodynamic derivatives that are the coefficients in the equation are listed in Table 2.

 Rudder force and moment coefficients: X^R, Y^R and N^R are measured by rudder test with some propeller loading conditions. Rudder normal force is also measured simultaneously in this test. These forces and moment are made non-dimensional and plotted in Fig.4 against longitudinal and lateral component of rudder normal force: F^Nsinδ and F^Ncosδ. The interactive force coefficients t^R, α^H and X^H in eq.(5) are obtained from the gradients of these coefficients, and listed in Table 2.

 From the measurement of rudder normal forces for various propeller loading, the parameters with longitudinal rudder inflow velocity in eq. (9) can be obtained.

　

　

 The identified characteristic of longitudinal rudder inflow velocity: UR is shown in Fig.5 as the ratio of UR (=( 1 - w)u) and analyzed parameter ε, κ are listed in Table 2.

　

　

　

 From the measurement of rudder force during CMT or oblique towing test with rudder angle, the parameters of lateral rudder inflow velocity in eq. (9): γR and lR be obtained. The identified characteristic of lateral inflow velocity is shown in Fig.6, and parameter γR and lR are listed in Table 2.

 These measurements have been performed with ship model A,B,C,D and F. The obtained hydrodynamic derivatives and coefficients are listed in Table 2.