Rewriting this review thanks to steam deleting it during the recommendation update.
If you own a boxed copy of this game, chances are it runs fine but is a little lag-prone. Your best bet is to never update it, as it will then turn into the patched thing that steam sells - that is something you really do not want.
I own a copy of each, one on here and a retail copy. The patched copy steam sells is utter garbage, it has been updated and modified so much it forgets settings, the waves glitch out like crazy, and the rain goes into spasmodic LSD-infused fits of unawesome on the highest setting. The addons for this copy can be bought but roughly half the owners cannot get them to register and therefore cannot use them. Note too the steam overlay does not work with it, and time played is counted only on the launcher, which runs for less than a minute when you start up the game - I've logged over 30 hours on this before the last patch killed the game for me, but steam thinks otherwise.
If you really want a ship simulator, there are far better offerings outside of steam. It's a pity this heap doesn't have a competitor on here after all this time, but just because it's the only option for steam users doesn't mean you should hit that "Add to Cart" button.