VisualSMP Training Class

1
VisualSMP Training Class

• July 24, 2008
• Changben Jiang, Ph.D.

2
Training Agenda

• SMP Introduction
• VisualSMP Introduction
• Monohull Base Modules
• Monohull Regular Wave Module
• Monohull Irregular Wave Module
• Time History Module
• Hands-on examples
• SMP output

3
What is SMP

• SMP is a result of
• 20th century advances in Applied Mathematics and
  Hydrodynamics
• 20th centurys Statistics Theory
• 20th centurys Control Theory
• SMP is linear 2D 0 speed hydrodynamics, Frank
  Close Fit, Haskind relations
• SMP is based on strip theory for forward speed
  correction (Salveson)
• SMP is based on linear random wave theory (St.
  Dennis and Pierson), both long-crested and
  short-crested waves
• SMP is US Navys 35 years of research in linear
  ship motion, motion evaluation, etc.
  Unfortunately, not much development or support on
  the navys side anymore.
• SMP is extensive in theory, research, and
  functionality
• SMP is still a work horse for what it is designed
  to do

4
What SMP Can Do

• Slender mono-hull, low, medium and modest high
  speed
• Moderate full hull at low to medium speed
• Low to moderate Sea states, LC and SC
• Predictions of Heave and Pitch motion are
  reliable and verified
• Predictions of Roll motion are less reliable but
  SMP has extensive roll damping research.
  Nonlinear roll motion is treated in a
  quasi-linear iterative manner.
• Predictions of surge, sway and yaw are less
  reliable and should be used with caution. SMP is
  not a maneuvering program.
• All kinds of ship motion statistics, extensive
  output.

5
What SMP Can Do, continued

• It can also generate time histories
• Ship motion evaluation
• Ship shear, bending and torsion loads statistics
  for fatigue analysis
• Lin-Reed added wave resistance
• SWATH module

6
Frequency Domain vs Time Domain

• Frequency domain is linear or quasi-linear. It is
  very fast. It can produce motion statistics for
  all the sea states in matter of seconds.
  Frequency domain solution is extensive in
  formulation.
• Time domain has to be done one sea state at a
  time. It is slow and time consuming if multiple
  sea states are of interest. One can put any kinds
  of forces, linear or non-linear in the equation.
• To use frequency domain solution in non-linear
  time domain simulation, one need to use
  convolution integral for radiation forces.

7
Ship Hydrodynamics Challenges

• Calm water forward speed problem Many theories,
  methods and programs. Numerical towing tank is
  still a dream.
• Maneuvering (surge, sway and yaw) or horizontal
  plan motion dominates by viscosity. Even tank
  tests often yield non-satisfory results.
• Ship Motion (heave, pitch and roll) can be
  numerically predicted to engineering acceptable
  accuracy with viscous roll damping correction.

8
Roll Nonlinear Damping Modeling

• Bilge keel
• Fins, passive, active/controlled
• Skeg, Rudder and Sonar dome
• Passive anti-roll devices U-Tube, Free-surface
  tank, moving weight
• Propeller shaft
• Shaft bracket
• Propeller

9
What SMP Can NOT Do

• Two body interaction
• No wind, no current, no mooring, no fendering
• Not a maneuvering program. No autopilot.
• Not true time domain simulation
• Cannot do barge or full hull in moderate or high
  speeds
• Cannot do planning hull
• Cannot do regular catamaran
• Not in very high seas

10
History of VisualSMP

• VisualSMP was created in 1999 as a result of a
  Cooperative Agreement between Proteus Engineering
  and NAVSEA.
• NAVSEA supplied the source code for SMP95, SEP96,
  STH97, and SWMP96.
• Proteus created a graphical user interface for
  pre- and post-processing, as well a time-history
  based visualization program.
• Proteus distributes VisualSMP commercially, and
  provides training and technical support.

11
SMP and VSMP Histories

• US Navy official versions SMP81, SMP84, SMP87
  and SMP95
• Many modifications and improvements to SMP95
  after 1995 but it is still called SMP95
• Visual SMP has almost all of the most recent
  SMP95 improvements
• Visual SMP makes the input preparation and output
  processing much easier and faster.
• Using Visual SMP could potentially avoid some
  mistakes.
• SMP and VSMP has the same core.

12
VisualSMP
VisualSMP SEP
Limiting Significant Wave Heights
PTO World Maps
RAO Plots
VisualSMP Base Modules Monohull Regular
Waves Monohull Irregular Waves SWATH Regular
Waves SWATH Irregular Waves
VisualSMP STH
Speed Polar Response Plots
Module Text Output Files
VisualSMP Visualizer
Origin 6DOF TH TH of motions of any point TH of
wave at any point Relative motion of any point
HPL Splined Geometry File
13
VisualSMP Data Flow
14
VSMP Basic Program Files
15
Important VisualSMP Files
16
Monohull VisualSMP Analysis Process
17
Sources of Hull Geometry

• FastShip Sections Export
• DXF Polylines via FastShip DXF2IDF Translator
• clipped to waterline (or main deck)
• Proper orientation
• GHS style Offset Table
• DXF and other format via GHS model convertor
• Manual Offset Entry
• New Geometry Manipulation Utilities

18
New Geometry Manipulation Utilities

• Modify Geometry clip offset to even keel
  waterline or trim waterline
• Make Even Point Spacing, specified by the user.
  Do it section by section.
• Delete dry stations
• Add point stations at bow and stern
• Add up to 70 stations, each station with 70
  points
• All knuckle points will be preserved

19
Make SMP Work Best For You

• Use more stations on bow, stern and other rapid
  shape variation areas. (lt70)
• Points evenly spaced in girth (lt70)
• Knuckles allowed
• Used for hydrostatics only
• 2 or more non-knuckle pts between knuckles
• Small bilge keels on knuckles for roll damping
• Use bilge keel if there is one. Use bilge keel
  for small bilge radius as well.
• Include skeg in offsets and as appendage
• Use 2.0 for roll nonlinear damping iteration

20
Appendage Modeling

• Bilge Keels
• Rudders
• Skegs
• Active/Passive Fin Stabilizers
• Roll Reduction Tanks or Moving Weights
• Sonar Dome
• Propellers, shafts, brackets

21
Running SMP

• Must save file before running
• Applies to all VisualSMP modules
• Validation tool gives clues as to potential
  problem areas but not fool proof
• Various viewers/post-processors facilitate review
  of computed output
• Text output files (.out, .oot, .log)
• Graphical output files (.smr, .rpt)

22
What Kind Of Background You Need To Use SMP

• Even though VSMP makes things easier for you, I
  still strongly suggest that you read PNA to have
  some general knowledge about waves, linear
  system, frequency domain solutions and motion
  statistics.
• VSMP has a decent documentation. Reading the
  manual is encouraged.
• There are lots of information has yet to be
  incorporated into VSMP manual. Call tech support
  if you are not sure about something.

23
Common Mistakes

• Use clouds of points in small curvature area and
  sparse distribution at other areas
• Bilge keel input (stations crossed)
• Almost all the x-position input should be in
  station numbers
• Confusion about buoyancy center, CG, origin,
  coordinate system, heading definition, etc
• Check options that require extra input, Load
  RAO, for example
• RAO definition SMP RAOTF2
• Misinterpretation of other output.

24
Wave Spectra In SMP

• BRETSCHNEIDER 2-parameter spectrum (fully
  developed)
• Jonswap wave spectrum (fetch limited seas)

25
SMP Input Coordinate System

• x in station , x0 at FP, 20 at AP, must have
  x10, positive backwards.
• y positive on port, y0 at CL
• z0 at BL, positive up
• Even trim, Lcg is at Lcb

26
SMP Internal Computational Coordinate System

• x in meter or feet x0 at Lcg, positive forward.
  Even trim, Lcg is at Lcb
• y positive on port, y0 at CL
• z0 at WL, positive up
• Earth-fixed, forward moving at constant mean
  speed
• Heading angle follows right-hand rule
• Normally the user dont need to worry about this.
  However

27
Please Note

• SMP Output are for the origin of the internal
  coordinate system (LCG, CL, WL) not (LCG, CL,
  VCG)
• Heading definition in SMP output and STH input
  0head, 180following, 90STBD BEAM. This is for
  the convenience of the ship operators and
  aircraft pilots
• STH wave elevation is for the origin (LCG, CL,
  WL)
• STH output and subsequent VSMP time histories are
  referenced to the internal coordinate system.

28
SMP Heading Definition

• Input and Output heading definition follows ship
  and aircraft operators conventions
• Internal Computational heading definition follows
  right-hand rule.
• Relation of the two One 180 the other

29
VisualSMP STH

• Generates time histories of 6 DOF ship responses
  at the origin from frequency domain results
• Uses regular wave transfer functions
• Accounts for relative phase of waves and
  responses
• Employs randomly and uniformly distributed phases

30
Wave Time History at the Origin

• In a earth-fixed, forward moving coordinates

31
Wave Elevation At An Arbitrary Point

• Where Kw2/g is the wave number, m is the
  computational heading angle, wEK is the encounter
  wave frequency for the k-th wave component

32
Origin Motion Time Histories

• rLC(t)x(t), y(t), z(t), f(t), q(t), y(t) is the
  6DOF origin motion caused by long-crested wave
• Where RAK is the amplitude of ship transfer
  function at the wave encounter frequency wEK ,
  The phase angle eEK refer to the phase of the
  ship response with respect to the wave elevation
  at the origin.
• RAK and eEK are the transfer function solved by
  SMP.
• (RAO RAK2)

33
Motion Time Histories of An Arbitrary Point (x,
y, z,)

• can be derived from the motion of the origin
• Where is x(t), y(t), z(t), f(t), q(t), y(t) are
  the origin motion time histories. Rotations are
  around earth fixed axes.

34
Wave Force Components

• Froude-Krylov forces due to the pressure field in
  the undisturbed incident wave
• Diffraction forces due to the scattering of the
  incident wave field
• Radiation forces due to the radiated wave field
  arising from body motions. The part in phase with
  acceleration is added mass coefficient. The part
  in phase with the velocity is the wave making
  damping Coefficient.

35
Ship Motion Transfer Function
36
VisualSMP STH Uses

• Input to flight simulators for launch and
  recovery of aircraft on moving decks
• Used for determining forces/effects on equipment,
  aircraft, munitions, or anything on or in the
  ship.
• Utilized for human factors considerations and the
  occurrence of Motion-Induced Interruptions (MII).
• Helpful in developing/evaluating limitations on
  shipboard systems
• Generates input to the seakeeping visualization
  tool

37
VisualSMP Visualizer

• VisualSMP uses transfer functions to generate
  time histories for the waves and the vessel
  motions in irregular seas, in 6 degrees of
  freedom, using STH97 (STH97 is also available
  separately from the Visualization program).
• Both the numerical time histories and the cosine
  coefficients for use in visualizations and
  simulations are computed.
• The VisualSMP visualization program uses the
  cosine coefficients and a geometry model from an
  HSF (HOOPS Stream File http//www.openhsf.org)
  or HMF file (HOOPS Metafile, Tech Soft America)
  to simulate the ship in a seaway at a fixed
  heading and speed.

• Allows rotation and viewing from any angle.
• Buoys can be defined to help visualize forward
  seed.
• Users view can be from off the ship or from the
  bridge.

38
Standard SMP Output

• SMP output are very extensive. They are all
  frequency domain and statistical output
• Output data files that are saved for VSMP
  subsequent run and post-processing
• Formated plain text output files Reg.out and
  Irg.oot.

39
SMPReg.out

• Input record echo, tables of ship and appendage
  particulars.
• Hydrostatics disp, WL properties, Section
  properties, buoyancy center, GM, etc.
• Mass properties and subset of coefficients of the
  equations of motion
• Roll damping printout and roll decay coefficients
  for the fully-appended hull
• Zero speed (non-)dimensional added mass and
  damping coefficients

40
SMPIRGW,oot

• RSV/T0E Table
• Single amplitude Response Statistical Values
  (RSV)
• Periods of maximum energy in the response
  encounter spectra (T0E).
• Response Amplitude Operators (RAO) tables
• RAO and their phase angles for the
  six-degree-of-freedom responses at the origin,
  surge, sway, heave, roll, pitch, and yaw. RAO is
  actually RAO2
• Added Resistance Operator (ARO)
• AROAdded Drag / WA2

41
RSV/T0E Table

• Each table contains predictions for a single ship
  response, at a particular location, for a
  particular wave height all speeds for headings
  from zero through 180 degrees for symmetric
  responses and zero through 360 degrees for
  asymmetric responses and for a range of modal
  wave periods
• Roll predictions are non-linear by roll angle and
  thus sea state
• The statistic used in the tables is specified by
  the user. This statistic is derived from a
  Rayleigh distribution and is applied to all
  responses

42
Available RSV/T0E Table

• Origin displacements, velocities and
  accelerations.
• Absolute motion locations, tables of the
  displacements, velocities and accelerations in
  earth and body axis,
• Motion sickness and motion-induced interruptions
• Relative motion locations, tables of relative
  motion, relative velocity, and then
• Probabilities of slamming, submergence, or
  emergence, are optionally provided. In this last
  case, the pairs of numbers in the tables are
  probabilities x 100/number of occurrences per
  hour rather than RSV/ T0E values.
• Slam pressures or forces are optionally provided
  in pairs of pressure or force/number of
  occurrences per hour.
• Optional output of a user defined severe motion
  table is available.
• Optional output of the shear forces, torsional
  moment, and bending moments

43
RSV/T0E Table, Example

• LONGCRESTED - BRETSCHNEIDER
• SIGNIFICANT WAVE HEIGHT
  16.00 FEET
• SWAY VELOCITY
• (FEET/SEC)
• Significant SA VALUE /
  ENCOUNTERED MODAL PERIOD (TOE)
• 
  SHIP HEADING ANGLE IN DEGREES
• V T0 HEAD
  STBD BEAM
  FOLLOW
• 0 15 30 45
  60 75 90 105 120
  135 150 165 180
• 0 9 0.00/99 0.24/11 0.52/10 0.97/10
  1.73/10 2.98/ 9 3.89/ 9 2.89/ 9 1.76/10
  1.01/10 0.55/10 0.25/11 0.00/99
• 11 0.00/99 0.34/14 0.75/12 1.30/11
  2.09/11 3.11/10 3.77/10 3.12/10 2.22/11
  1.46/13 0.87/13 0.41/14 0.00/99
• 13 0.00/99 0.46/14 0.95/14 1.55/14
  2.28/14 3.11/14 3.60/14 3.18/14 2.46/14
  1.75/14 1.11/14 0.54/14 0.00/99
• 15 0.00/99 0.53/15 1.09/15 1.69/15
  2.36/14 3.04/14 3.42/14 3.12/14 2.52/14
  1.87/14 1.22/14 0.61/14 0.00/99

44
RSV/T0E Table, Example

• LONGCRESTED -
  BRETSCHNEIDER
• SIGNIFICANT WAVE HEIGHT
  16.00 FEET
• Helo landing XFP 18.45
  YCL 0.00 ZBL 35.00
• LATERAL ACCELERATION
• (G)
• (ACC. X 100)
• Significant SA VALUE /
  ENCOUNTERED MODAL PERIOD (TOE)
• 
  SHIP HEADING ANGLE IN DEGREES
• V T0 HEAD
  STBD BEAM
  FOLLOW
• 0 15 30 45
  60 75 90 105 120
  135 150 165 180
• 0 9 0.00/99 1.89/10 4.17/ 9 7.23/ 9
  11.09/ 8 13.58/ 7 11.00/ 8 13.19/ 7 9.84/ 8
  6.32/ 9 3.65/10 1.66/10 0.00/99
• 11 0.00/99 2.14/10 4.47/10 7.16/ 9
  9.95/ 8 11.24/ 8 9.35/ 9 11.12/ 8 9.19/ 9
  6.56/10 4.12/10 1.97/10 0.00/99

45
RSV/T0E Table, Example

• LONGCRESTED
  BRETSCHNEIDER
• SIGNIFICANT WAVE HEIGHT 16.00
  FEET
• wetness per hr XFP 16.50 YCL
  29.28 ZBL 30.53
• RELATIVE VELOCITY
• (FEET/SEC)
• Significant SA VALUE / ENCOUNTERED
  MODAL PERIOD (TOE)
• 
  SHIP HEADING ANGLE IN DEGREES
• V T0 HEAD
  PORT BEAM
  FOLLOW
• 360 345 330 315
  300 285 270 255 240
  225 210 195 180
• 0 9 6.66/ 7 6.77/ 7 6.78/ 6 6.67/ 6
  6.70/ 5 7.80/ 6 8.49/ 5 8.75/ 6 7.33/ 7
  6.38/ 7 6.09/ 7 6.14/ 6 6.25/ 6
• 11 4.80/ 7 4.93/ 7 5.06/ 6 5.18/13
  5.45/13 6.24/13 6.58/13 6.84/13 6.00/13
  5.29/13 4.87/13 4.66/ 8 4.57/ 8
• 13 3.56/ 7 3.76/ 7 4.03/13 4.31/13
  4.64/13 5.18/13 5.36/13 5.57/13 5.06/13
  4.53/13 4.06/13 3.68/13 3.42/ 8
• 15 2.72/ 7 2.96/ 7 3.30/13 3.64/13
  3.96/13 4.34/13 4.44/13 4.61/13 4.28/13
  3.86/13 3.41/13 2.96/13 2.64/ 8

46
RSV/T0E Table, Example

• SHORTCRESTED
• SIGNIFICANT WAVE HEIGHT
  16.00 FEET
• wetness per hr XFP 16.50 YCL
  29.28 ZBL 30.53
• SUBMERGENCE
• PROBABILITY x100 / NO. OF
  OCCURRENCES PER HOUR
• 
  SHIP HEADING ANGLE IN DEGREES
• V T0 HEAD
  STBD BEAM
  FOLLOW
• 0 15 30 45
  60 75 90 105 120
  135 150 165 180
• 0 9 0.4/ 2 0.3/ 1 0.3/ 1 0.3/
  1 0.5/ 2 0.6/ 3 0.7/ 4 0.6/ 3 0.1/
  0 0.1/ 0 0.1/ 0 0.2/ 1 0.2/ 1
• 11 0.0/ 0 0.0/ 0 0.1/ 0 0.4/
  2 1.0/ 4 1.2/ 5 1.3/ 5 1.3/ 5 0.4/
  1 0.1/ 0 0.0/ 0 0.0/ 0 0.0/ 0
• 13 0.0/ 0 0.0/ 0 0.0/ 0 0.4/
  1 1.0/ 3 1.2/ 4 1.2/ 4 1.3/ 5 0.7/
  2 0.2/ 0 0.0/ 0 0.0/ 0 0.0/ 0
• 15 0.0/ 0 0.0/ 0 0.0/ 0 0.2/
  0 0.5/ 1 0.6/ 2 0.6/ 2 0.7/ 2 0.4/
  1 0.1/ 0 0.0/ 0 0.0/ 0 0.0/ 0
• 17 0.0/ 0 0.0/ 0 0.0/ 0 0.0/
  0 0.1/ 0 0.2/ 0 0.2/ 0 0.2/ 0 0.1/
  0 0.0/ 0 0.0/ 0 0.0/ 0 0.0/ 0

47
RSV/T0E Table, Example

• 
  SHORTCRESTED - BRETSCHNEIDER
• SIGNIFICANT WAVE HEIGHT
  16.00 FEET
• ADDED RESISTANCE
• (LBS)
• (FORCE / 105)
• Significant SA VALUE / ENCOUNTERED
  MODAL PERIOD (TOE)
• 
  SHIP HEADING ANGLE IN DEGREES
• V T0 HEAD
  STBD BEAM
  FOLLOW
• 0 15 30 45
  60 75 90 105 120
  135 150 165 180
• 0 9 0.893/ 9 0.877/ 9 0.822/ 9
  0.712/ 9 0.539/ 9 0.309/ 9 0.046/ 8
  -0.215/99 -0.440/99 -0.606/99 -0.708/99
  -0.758/99 -0.772/99
• 11 0.835/10 0.815/10 0.752/10
  0.640/10 0.475/10 0.266/10 0.033/ 8
  -0.197/99 -0.396/99 -0.548/99 -0.648/99
  -0.701/99 -0.717/99
• 13 0.748/12 0.727/12 0.664/12
  0.556/12 0.406/12 0.222/12 0.021/ 9
  -0.178/99 -0.353/99 -0.491/99 -0.587/99
  -0.642/99 -0.659/99
• 15 0.651/14 0.631/14 0.572/14
  0.475/14 0.343/14 0.185/14 0.013/ 9
  -0.156/99 -0.308/99 -0.431/99 -0.519/99
  -0.572/99 -0.589/99
• 17 0.559/15 0.541/15 0.489/15
  0.403/15 0.289/15 0.154/15 0.008/ 9
  -0.136/99 -0.266/99 -0.374/99 -0.453/99
  -0.501/99 -0.517/99

48
RAO tables

• One RAO table is provided for each speed,
  heading, and sea state
• The vertical mode response RAOs (surge, heave,
  and pitch) are linear and are independent of sea
  state. The lateral response RAOs (sway, roll, and
  yaw) are nonlinear and vary with sea state.
• The lateral RAOs are obtained by interpolation,
  using the roll RSV value computed for the
  particular speed, heading, significant wave
  height, and modal period.
• It should be noted that the roll RSV value also
  depends on the Rayleigh statistic specified in
  the input.
• Also RAO tables are provided for only the first
  sea state in head or following waves, where sway,
  roll, and yaw are zero.
• The total number of RAO tables output is, Number
  of speeds x (2 11 x number of sea states)

49
RAO table, Example

• RESPONSE AMPLITUDE OPERATORS (RAOS) AND
  PHASES
• 
  SHIP SPEED 0. KNOTS
• 
  SHIP HEADING 75. DEGREES
• SEA
  STATE SIGNIFICANT WAVE HEIGHT 16.00 FEET
• 
  MODAL PERIOD 11. SECONDS
• 
  STATISTIC 2.00 (Significant )
• OMEGA OMEGAE SURGE SWAY
  HEAVE ROLL
  PITCH YAW
• AMPL. PHASE AMPL.
  PHASE AMPL. PHASE AMPL. PHASE
  AMPL. PHASE AMPL. PHASE
• 0.200 0.200 1.8976E-01 163.9 9.1507E-01
  -89.4 9.9869E-01 0.0 6.7427E-03 -94.9
  3.5061E-04 -90.6 3.3505E-04 11.0
• 0.221 0.221 1.2971E-01 160.0 9.0624E-01
  -89.6 9.9861E-01 0.0 1.0757E-02 -95.9
  5.1933E-04 -90.7 4.3895E-04 10.3
• 0.241 0.241 9.3741E-02 155.9 8.9680E-01
  -89.9 9.9849E-01 0.0 1.6660E-02 -97.1
  7.3932E-04 -90.8 5.5823E-04 9.6
• 0.261 0.261 7.1192E-02 151.7 8.8740E-01
  -90.2 9.9809E-01 0.0 2.5292E-02 -98.4
  1.0183E-03 -91.0 6.9970E-04 8.9
• 0.280 0.280 5.6521E-02 147.5 8.7873E-01
  -90.6 9.9736E-01 0.0 3.7980E-02 -99.8
  1.3640E-03 -91.1 8.7975E-04 8.6
• 0.300 0.300 4.6674E-02 143.5 8.7123E-01
  -90.9 9.9635E-01 0.0 5.6869E-02 -101.5
  1.7847E-03 -91.3 1.1189E-03 8.8
• 0.319 0.319 3.9877E-02 139.7 8.6514E-01
  -91.1 9.9509E-01 0.0 8.5514E-02 -103.3
  2.2884E-03 -91.5 1.4390E-03 9.5
• 0.337 0.337 3.5072E-02 136.2 8.6066E-01
  -91.3 9.9360E-01 0.0 1.3008E-01 -105.5
  2.8833E-03 -91.7 1.8679E-03 10.7
• 0.356 0.356 3.1598E-02 133.0 8.5809E-01
  -91.5 9.9189E-01 0.0 2.0184E-01 -108.0
  3.5774E-03 -92.0 2.4476E-03 12.2

50
ARO table, example

• ADDED RESISTANCE
  OPERATOR
• SHIP SPEED 0. KNOTS
• SHIP HEADING 180. DEGREES
• SEA STATE SIGNIFICANT WAVE HEIGHT
  16.00 FEET
• MODAL PERIOD 11. SECONDS
• STATISTIC 2.00 (Significant )
• OMEGA OMEGAE A R O
• 0.200 0.200 -4.2557E02
• 0.221 0.221 -5.1824E02
• 0.241 0.241 -6.1874E02
• 0.261 0.261 -7.2659E02
• 0.280 0.280 -8.4129E02
• 0.300 0.300 -9.6225E02
• 0.319 0.319 -1.0888E03
• 0.337 0.337 -1.2199E03
• 0.356 0.356 -1.3546E03
• 0.374 0.374 -1.4914E03

51
RAO plots, example
52
Polar Plot Example
53
VisualSMP Assumptions

• Slender Body Theory
• L/B gt 4.5
• Responses assumed to be small, linear, and
  harmonic
• Instantaneous wave elevations and ship responses
  are assumed Gaussian-distributed with zero mean
• Wave and response amplitudes are assumed
  Rayleigh-distributed
• Non-linear treatment of roll response (roll
  iteration)
• Irregular Seaway
• The random sea waves can be represented as a sum
  of simple sine waves whose amplitudes are
  obtained from specified wave spectral densities
  and whose phases are random with a uniform
  distribution
• The responses of a ship to the random sea waves
  can be obtained as the sum of the ship responses
  to the individual sine waves that compose the
  random sea.
• The irregular seas are modeled using either the
  two parameter Bretschneider, the three parameter
  Jonswap, or the six parameter Ochi-Hubble wave
  spectral models.
• Both long-crested and short-crested results are
  provided short-crested waves are generated using
  a cosine squared spreading function.

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Single Amplitude Statistics
55
What data does Monohull VisualSMP generate?

• 6 DOF Rigid Body Motions (displacements,
  velocities, accelerations) at the CG
• Absolute longitudinal, lateral, vertical
  (earth-referenced) displacements, velocities,
  accelerations at up to 10 arbitrary locations
• Relative displacements and velocities at up to 10
  arbitrary locations
• Probability of slamming, submergence, emergence
• Added resistance in waves
• Slamming pressures and forces