"Our on-board computer uses a Commell LS-371 3.5in embedded motherboard with an Intel Core Duo 2.0 GHz processor and 2GB of RAM. We use a Patriot Memory Warp II 32 GB solid state drive (SSD) for on-board storage."
This isn't anything big in the computing stakes - just a PC in a sub, as I suspected. This isn't a marvellous achievement computing-wise - they've programmed a computer-visualisation app (using pygame at some points!) on their desktop and slapped it onto an identically specced SBC inside a sub.
If they've done it on a 100MHz processor with 32Mb RAM or less (with support chips), then it would be much more worthy of them using the word "embedded". As it is, it's just slapping GHz and Gb at the problem.
However, their pages on their vehicles are infinitely more interesting from an algorithm / engineering point of view. The details of PC specification and OS are completely irrelevant - they could have slapped XP on that sub and run the same programs and nobody would have even noticed.