SUBSIM to SAMSON to XMF – 30 years later and still going strong

Since 1986, MARIN has used in-house soft- ware SUBSIM for predicting the manoeuvring behaviour of submarines. Using the hull geometry as input, this time domain simu- lation applies slender body theory in all six degrees of freedom. In addition, the program contains nonlinear models for hydrostatics, cross-flow drag, fins, sail, masts and propellers. Each lifting surface generates its own trailing vortex, causing interaction effects. Given the modest computational complexity, SUBSIM is highly suitable for real-time interactive simulation, as well as the early design stage.

Gerben de Vries

SUBSIM was renamed SAMSON after the inclusion of ballast and trim tanks. This functionality made it possible to perform safety procedure assessments. It also com- pleted the necessary functionality for the Dutch Navy training simulator. Over the years, the codebase became a colourful blend of FORTRAN77, Fortran 90, Java, C and Delphi. Requested and partly funded by DMO, during 2015-2016, the program has been ported to MARIN’s eXtensible

Modelling Framework (XMF) for time domain simulation, such that the hydrodynamic aspect models can be continuously extended and improved where necessary.

In its new architecture, submarine simulation technology has become more accessible. For example, it is now possible to combine a FREDYN frigate model with a SUBSIM submarine model. The models can also be run in MARIN’s Dolphin full mission bridge simulator architecture. This facilitates many useful tactical or operational research and training scenarios.

Hard coded autopilot functionality has been replaced by a more generic interface. For example an autopilot, ballast control system or tactical AI can be prototyped in a scripting language such as Lua. Additionally, third party autopilot vendor steering modules can easily be connected to the hydromechanical simulation modules.

With its renewal, SUBSIM is ready to build on 30 years of heritage.

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