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This package consists of 14 integrated programs that perform required regulatory calculations and produce stability books for vessels.  Capabilities include the ability to define and display any shape hull, compartment, tank, or appendage, and the ability to calculate and display the station properties, hydrostatics, and stability for any combination of intact or damaged hull, appendages, tanks, or compartments.

Package Programs

1.  Nautilus Executive Control Program
2.  Principal Dimensions Module
3.  Convert Hull Module
4.  Lackenby Hull Variation Module
5.  Weights Management Module
6.  Offsets Definition Module
7.  Design/Digitize Module
8.  Compartment/Appendage Definition Module
9.  3D Hull Drawing Module
10. Station Properties Module
11. Hydrostatics/Tank Capacities Module
12. Stability Module
13. Floodable Length Module
14. Longitudinal Strength Module

In addition to these programs, you will also receive a 500+ page program manual and a 350 page Introduction/Tutorial manual.


Body Plan View of SS United States


Package Background

This software is not a Ships' Hull Characteristics Program (SHCP) derivative or a variation of someone else's program.  We wrote every line of code in these programs from the ground


up to take advantage of the latest techniques in numerical analysis and computer graphics.  From our work tearing apart SHCP in the 1970's, we learned all of its idiosyncrasies, weaknesses, and limitations and decided to write our own completely new set of programs.

Our goal was to have programs which produce fast, accurate, verifiable results, and at the same time, provide a simple user interface.  For example, we use interpolated B-spline curves for stations to allow for an unlimited range of hull shapes and we use line integrals for all of our calculations so that tabulated results will always match the plotted results.  The manual devotes a whole chapter to calculation methods and verifying results.  This allows you to analyze the results and not treat the programs as mysterious black box calculators.

Hull Station Definition

These programs use a "station definition" for performing all calculations.  This consists of up to 50 stations located arbitrarily along the hull's length.  Each station is defined by offsets and continuity (breakpoint) indicators.  These indicators tell the program whether there is a smooth curve, a knuckle, or a discontinuous point at each offset.  Indicators are also used with each station to help the program accurately perform all longitudinal integrations.  Using this definition, you can accurately define any type of hull, including monohulls, catamarans, trimarans, and swath ships.

Hull Input

Hull shapes can be defined by typing-in a table of offsets using the Offsets Module, digitizing an existing bodyplan using the Design/Digitize module, or by defining station shapes interactively using the Design/Digitize module.  Once defined, you can modify the shape of the hull using either of these programs and display its shape using the 3D Hull Drawing module.  Another way to obtain a hull shape is by reading in a data file containing a hull form defined by the NWS, SHCP, GHS, or ".OFF" format.

Yet another method for creating a starting hull shape is by modifying an existing hull shape using either of two techniques.  The first technique applies a scaling factor to resize an existing hull shape.  The length, beam, and draft can be scaled independently.  The second technique (Lackenby Hull Variation module) allows you to create derivative hulls by modifying their prismatic coefficient, their LCB, or their length of parallel middle-body.  These changes are made without affecting the hull's length, beam, or draft.


Sectional Area Curve With Flooded Compartment


Compartment/Appendage Definition

Compartments (and appendages) can be defined using several methods in the Compartment Definition module.  The most common procedure is to "clip" the hull with any combination of bulkheads and decks.  For example, you might define a wing tank with a forward bulkhead at 150 feet, an aft bulkhead at 200 feet, a lower deck at 20 feet, and an inside longitudinal bulkhead at 10 feet.  The compartment will then be defined by these bulkheads, decks, and the outside shape of the hull.

The Compartment program also allows you to define the detailed 3D shape of a sounding tube.  A cross-section of the hull showing the compartment (tank) and sounding tube can then be drawn by the 3D Hull Drawing module.  The drawing program can also display the 3D view of the hull showing selected compartments and sounding tubes with user-defined colors.

Compartments can also be quickly defined by an assortment of boxes, cylinders, and cones.  You can also use the Offsets or Design/Digitize modules to define and modify unusual compartment shapes.

Station Properties Module

This module calculates, prints, and plots up to 17 geometric properties of each station, for each specified combination of draft, trim, and heel angle.  It will also display or plot the profile of the vessel showing the sheer line, margin line, any defined hog or sag, and the defined waterline or wave.  For any draft, trim, and heel, the module will also determine the shortest distance between the sheer curve and the water.

This module can be used with the hull definition, any compartment definition, or a combination of the two.  This allows you to evaluate the properties of the compartments (tanks, appendages) alone or with the hull.


Hydrostatics Module

The Hydrostatics module calculates the volumetric properties of a hull and compartments (including tanks and appendages).  The calculations can be performed on the hull, on one or more selected compartments, or upon the hull plus the compartments.  This allows you to use this module to calculate tank properties such as ullages, volumes, centers, and waterplane inertias.  The module is broken into two sections: one for printing tabulated results and the other for plotting results over a range of drafts.

Floodable Length Module

This module allows you to print and plot the floodable lengths of a vessel using a number of permeabilities.  Floodable length is defined as the longitudinal length of a watertight compartment (flooded side-to-side) that will cause the vessel to sink to the point where the waterline is tangent to the margin line.  The margin line has a default setting 3 inches below the sheer, but can be changed to any other position.  Plotted output can also include isosceles triangles showing the highest allowable compartment permeability.


Stability Module

This module allows you to analyze the stability (intact or flooded) of a hull using either of the following two methods:

Curve of Statical Stability - Prints or plots righting arms vs. heel angles for a specified design condition.  The hull is balanced for displacement and LCG at each angle.  Output includes righting moment, LCB, TCB, VCB, and areas under the righting and heeling arm curves at each condition.

Cross Curves of Stability - Prints or plots righting arms vs. displacement for various heel angles.  You specify the range of displacement, along with the desired heel angles.  LCG and LCB are balanced for each displacement.  Output includes righting moment, LCB, TCB, and VCB at each condition.


Cross Curves for Various Heel Angles


Optional Inputs

Hog or Sag of the Hull  -  This option allows you to specify a parabolic deflection (up=hog or down=sag) of the hull shape before calculations are performed.  The maximum deflection is at amidships, tapering off to zero at the forward and aft perpendiculars.

Trochoid or Cosine Waves  -  This option allows you to define either trochoid or cosine waves of any height, length, or position to use for calculating hull properties.

Free Surface Effects  -  This option allows you to define the free surface effects induced by one or more compartments.  The program uses a "moment of transferrence" method, including a correction for large heel angles (as defined in Principles of Naval Architecture).  The program determines corrected values for KG and all associated volumetric properties.

Heeling Arms  -  This option allows you to specify cosine or cosine-squared type heeling arm curves.  These curves cover virtually all regulatory requirements from wind heel to passenger heel.  The module will plot the curve and calculate the area under the curve up to each heel angle.

Weights Management Module

This program allows you to add, delete, and change weight information for a vessel.  Hundreds of individual weights can be entered and subdivided into any number of weight groups.  The total weight and the center of gravity (LCG, TCG, VCG) are automatically recalculated and displayed as each weight is entered.  A sorted full weight report or summary can then be printed showing all group and final totals.

The program also allows you to select a weight distribution


for each weight item (rectangular, triangular, trapezoidal, etc.).  The program uses these individual distributions to graphically create and plot a single weight curve.  This weight curve can then be immediately used by the Longitudinal Stength module to calculate the shear and bending moments for the hull.

A "Make-Up" weight can also be defined to make-up the difference between the currently entered weights and the "target" design displacement and LCG.  The program automatically calculates and updates this weight each time a new weight is entered.  A "Make-Up" weight distribution can also be calculated and added to the weight curve.  This allows you to use the Longitudinal Strength module without creating a weight  curve by hand.


Longitudinal Strength Module

This module allows you to calculate, print, and plot the longitudinal strength data of a vessel.  This information includes the light-ship, cargo, and total weight curves, the buoyancy curve, the curve of differences between total weight and buoyancy, the shear curve, and the bending moment curve.

The results can be calculated for any combination of draft, trim, or heel angle for the vessel, including the ability to specify a group of damaged compartments.  In addition, you can specify a hog or sag for the vessel and a trochoid or sinusoidal wave pattern.


Intact Stability Package - If you are interested only in the undamaged (intact) condition calculations, you can select our Intact Stability Package.  It contains all of the same programs, except for the Longitudinal Strength Module.  It can define appendages, but no internal compartment shapes and no compartment calculations are allowed.


Damaged Stability Package Highlights


o Up to 50 arbitrarily-shaped stations can be defined
o Up to 50 offset points allowed per station
o Automatic station interpolation for adding intermediate stations
o Any station spacing allowed (uses longitudinal breakpoints)
o Any shape defined using cubic B-splines and breakpoint indicators

o Stations defined by entering offsets, digitizing a body plan, and/or
  defining them interactively, on the computer screen.
o Appendages can be added or subtracted from hull definition
o Automatic hull stretching or shrinking in any direction
o Hull variation by changing prismatic, LCB, or parallel middle body

o Body plans can be plotted at any scale or sent to CAD package
o All stations can be faired interactively on the computer screen
o Stations can be drawn from any view in 3D, with hidden lines removed
o Form calculations can be done for any draft, trim or heel angle
o Define a parabolic hog/sag of the hull shape

o Define arbitrary cosine or trochoid wave
o Calculate free surface corrections
o Draw heeled and trimmed profile of hull on waterline or waves
o Over 40 plots can be produced, from sectional areas to cross curves
o Stability module can trim the hull to match the LCB with the LCG

o Stability module produces righting arm or cross curve plots
o Stability module allows definition of heeling arms
o Stability module calculates areas under righting and heeling arms
o Weights module tracks the total weights and centers for the vessel
o Hull definition converted to and from NWS, OFF, SHCP, and GHS formats

o All modules include help files for each input screen
o Includes 500 page manual and 350+ page Introduction and Tutorial
o Any shape compartment, tank, or appendage may be defined
o Compartments defined easily using a variety of methods
o Compartments drawn along with the hull in 3D using different colors

o Any cross-section of hull plus compartments can be drawn
o Any hull view can be sent to CAD package via "DXF" file
o Sounding tubes for tanks can be defined and drawn
o Compartment properties calculated for any draft, trim, or heel
o Determine inertias of tank waterplanes for free surface correction

o Calculate free surface corrections for any heel angle
o Calculate properties of hull, compartments, or both
o Plot all sectional curves minus flooded compartments
o Calculate, print, and plot floodable length curves
o Plot isosceles triangles on floodable length curves

o User-definable margin line
o Calculate, print, and plot longitudinal strength data: weight
  curves, buoyancy curve, shear curve, and bending moment curve
o Weights module can automatically create full weight curve
o Calculate distance to lowest down-flooding point on hull
o Easily select any combination of compartments to flood for
  Station Properties, Hydrostatics, and Stability

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