http://en.wikipedia.org/wiki/CSS_Manassas

Seeing I've had several ancestors who fought in the civil war, I'm
always intrigued with the effectiveness ( good or bad) of primitive
war machinery especially the iron clad vessels.

The "Rams" were amazing creations. It seem the Manassas especially
stands out - 143 ft. long and 33 ft. wide and carrying a cannon that
could hurl a 62 lb. shot not counting the 40 ft. iron spike to poke
holes in the hulls of the wooden ships...

I can't imagine being in a semi-submersible with little ventilation, a
cannon, a steam engine and no sound proofing as cannon balls violently
hitting the deck. I'd think that if the percussion (even from within)
didn't get you, the heat would. Even bracing for the ram could be
quite injurious, I'd think. All in all, I'm sure the whole crew was
eventually deaf.

Interesting portion of the Wiki link: "Manassas then ran into
murderous fire from the whole line of the Union fleet. She then
charged USS Mississippi and delivered a long glancing blow on her
hull, firing her only gun as she rammed. " Amazingly it survived only
to run aground and get pounded to it's death.

Another good article that has some layouts of the hull ....

http://www.history.navy.mil/photos/s...r/manassas.htm