The Narwhal is a modded/added sub to SH4.......its not in the stock game, no matter which version of the game you have. If you've got a Narwhal sub with a stock game (no mods activated) you've got big problems!
Follow the instructions for a clean install found
HERE in a "Sticky" on this forum page.
Make sure you follow the instructions as read.......especially the part about taking a "Snapshot" of your clean installed game files after adding JSGME. This way you can check your stock game files for any wrong doing after adding/removing mods to the game.