VisualSMP is a suite of tools used in the prediction and analysis of a ship's sea-keeping and loads characteristics. Included in VisualSMP is the US Navy's strip theory based frequency domain ship motion program (SMP), US Navy's sea-keeping analysis program (SEP), US Navy's standard time history program (STH and ACTH), and US Navy's sea-keeping program for SWATH (SWMP). The US Navy has selected Alion Proteus Engineering to distribute these tools commercially, and Proteus has used its experience in sea-keeping and sea loads analysis and software development to integrate and extend them, resulting in VisualSMP. VisualSMP adds a graphical pre- and post-processor, and a visualizer, together with tools to extend and refine the functionalities of SMP. Among many other things and past improvements, the most recent Alion additions and improvements are: (1) A suite of utilities to easily modify, refine and prepare the hull geometry; (2) Fully functional Ochi-Hubble family of wave spectra; (3) Motion and relative motion time histories outputs for short-crested waves; (4) Calculating the cargo latching forces at the specified deck surface and point in both long-crested and short-crested waves; (5) Quasi-nonlinear roll restoring force, i.e., using the actual GZ curve in transverse motion and loads calculations; (6) Calculate and output of the response band widths; (7) Calculate and output of the Zero-Crossing Response Period and the Average Response Period; (8) Calculate response statistics, such as the Most Probable Maximum Response in a specified length of time, based on the response's actual band-width instead of using narrow-band assumption; (9) Calculate the probability of exceeding a certain response (motion or loads) level in a specified length of time based on the response's actual band-width; (10) Calculate the number of occurrences of exceeding a certain response (motion or loads) level in a specified length of time based on the response's actual band-width; (11) Calculate the probability of exceeding and number of occurrences of exceeding a certain response level for a mission profile, which will include all the speeds and headings for various different combinations of wave heights and wave periods.

VisualSMP provides predictions of ship motions (i.e. displacements, velocities, and accelerations) and loads (i.e. shear, bending and torsion) for a ship advancing at constant speed, on arbitrary headings in both regular waves and irregular seas. 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. In addition to the 6DOF responses, VisualSMP will predict the absolute motion, velocity, and acceleration, as well as the relative motion and velocity for various locations on the ship. VisualSMP will calculate the probabilities and frequencies of submergence, emergence, and/or slamming occurrence, slamming pressure/force, MSI (motion sickness incidence) and MII (motion induced interruptions) for various locations on the ship. If the weight distribution is given, VisualSMP will calculate vertical and transverse shear forces, longitudinal and horizontal moments, and torsion moments at user's specified locations. For each of the above motion and load responses, VisualSMP can calculate various statistics (mentioned earlier) in a specified length of time based on the response's actual band-width. It also estimates added resistance in waves based on the work by Wen-Chin Lin and Arthur Reed, as documented in their paper "The Second Order Steady Force and Moment On a Ship Moving In An Oblique Seaway".

Alion has developed the graphical pre- and post-processor using the Microsoft Windows GUI. These tools speed the data input process and provide graphical tools to view the computed results. VisualSMP input models consist of hull offsets, appendage dimensions, and controller coefficients. The hull offsets are described to the system as points on sections, including the stem and stern profile. Both transverse and longitudinal knuckles are allowed. New Versions of VisualSMP feature powerful geometry input and manipulation utilities. These utilities make preparing offsets almost an automatic process. The user may import the offset table from FASTSHIP in an IDF format, or prepare the offsets in a GHS GF style text file. The offset points may go above the waterline. After IDF or GF file is imported into VisualSMP, the user can use 'Modify Sections' to clip the sections to a particular waterline, and then use other utilities to make point distribution to the user desired level section by section.The user may input up to 70 stations and 70 points per station, and may choose from the following list of appendage types to include in the calculations: Sonar Dome, Bilge Keels, Passive Fins, Active Fins, Shaft Brackets, Propellers, Propeller Shafting, Skeg, Rudders, and Roll Tanks.

The Sea-keeping Evaluation Module (SEP) can be used to estimate the seaworthiness of SWATH and monohull ships early in the design process. Estimation of the seaworthiness of ships can be useful in several ways. In early design studies, prediction of the effect of hull form modifications on ship motions can have an impact on the design, permitting the selection of a seaworthy hull form, from among those which meet other design requirements. The ability to readily analyze the relationship between hull form modifications and seaworthiness can allow consideration of many hull forms in a short period of time. Once a ship has been built, estimation of seaworthiness utilizing frequency domain prediction methods can facilitate prediction of the potential ability of the ship to carry out a new mission. This facilitates consideration of the effect of hull form modifications on performance.

Required input data for the SEP includes motion transfer functions which have been generated by either the SWATH module or SMP regular wave module as well as data files which contain results from analysis of Spectral Ocean Wave Model (SOWM) data. This data defines the joint probability of occurrence of significant wave height, spectral modal (peak) period, and wind speed for various geographical locations.

Although there are limitations to the analysis used in SEP, it provides the means of easily, quickly, and consistently estimating the seaworthiness of hull forms for a range of missions, giving consideration to a wide range of spectra and their probabilities of occurrence at a large number of geographical points. This method of predicting seaworthiness is useful in comparing the performance of a variety of hull forms.