Well, finally got the Proper Narwhal installed, and ran it out on a new career. ...or two. Which performances we are going to call "tests."
What it Can do.
Swiftly deal with a disabled merchant with its guns, and defeat a minelayer in open waters without much damage.
What it cannot do.
Sail across a convoy's "T" and gun it out with them. Merchants have 3" bow-chasers (lineage of the British 6-pounder gun?), and 9 of them make for a Large volume of fire. ...don't ask me how I know...
Surface in a Harbor and duel it out with everything docked there. ...I heard somebody did this, it certainly wasn't me...
So, it seems the best thing to do is Forget you have 2 6" guns, and just know that if you're forced to the surface by a lone escort you have a Slightly better chance of winning than other boats would. Which is "not very good."
It looks great btw, as advertised.