Description and geometry

1. Geometry

The objective hull form is a bare hull model of the US Navy combatant DTMB 5512 only equipped with bilge keels.

 

Model

 

Fixed model

Free model

Scale

-

1 : 46.588

M

3.048

M

3.052

M

0.410

M

0.136

Mass

Kg

83.35

82.55

COG-X

M

-0.0157

COG-Y

M

0.0

COG-Z

M

N/A

0.084

Kg×m2

N/A

1.98

Kg×m2

N/A

53.88

Kg×m2

44.35

49.99

COR-Roll

M

 

 

COR-Pitch

M

 

 

COR-Yaw

M

X=0.0, y=0.0

                COG: Center of gravity

                COR: Center of rotation

2. Coordinate system

The coordinate system and sign convention is a right-handed, horizontal, body-fixed coordinate system with x positive forward of mid-ship, y positive starboard of center line and z positive down from waterline.

Dynamic PMM

Static PMM

3. PMM motion equations

Prescribed motions in which the heading, , the surge, , the sway, , and yaw, , velocities and the surge, , sway, , and yaw, , accelerations (in the ships local (x, y) coordinate system) are known to any given time. The motion parameters can be described by the sway amplitude, , the yaw motion amplitude , and the number of PMM rotations per minute, .

1) PMM yaw motion

Heading angle

Yaw rate

 

Yaw acceleration

2) PMM sway motion

Transverse translation

Transverse velocity

Transverse acceleration

3) Motions in the ship fixed coordinate system

Sway velocity

Sway acceleration

Surge velocity

Surge acceleration

Yaw rate

Yaw acceleration

4. Data reduction equations

All forces are defined in a coordinate system following the ship, meaning that X-components act in the longitudinal direction of the ship and Y-components perpendicular to this direction. The yaw moment is taken with respect to the mid-ship position at. All hydrodynamic forces and moments should be non-dimensionalized by the following data reduction equations

  

 

 

 

where  is the water density. ,  and  are the total X- and Y-forces and the yaw moment, respectively. is the ship speed. It is constant in the static test, but it varies in the dynamic test.  is the lateral underwater area  defined as .  and  are the length between perpendiculars and the mean draft, respectively.  is also used as the characteristic arm for yaw moment.