CSS Virginia wasn't even as seaworthy as USS Monitor, however;
What happens when you show up for a fight, and the opponent doesn't? The CSS Virginia was busy sinking the Union fleet at Hampton Roads when the USS Monitor showed up. While sailing down from New York, the
USS Monitor almost foundered before arriving to meet the Virginia. What happens if the Federal ironclad sinks before the battle?
Except that CSS
Virginia is underpowered, overweight, close to unmanageable, and has the freeboard of a Boston whaler; other than that, it's brilliant.
After her conversion to an ironclad, Virginia wasn't even as seaworthy as USS
Monitor, however; she was more of a harbor defense vessel than
Monitor, actually.
Monitor's officers and men could actually contemplate a coastal voyage;
Virginia's could not
.
As it is, the US blockaders can withdraw to the entrance of Chesapeake Bay and still have control over any shipping attempting to get in or out of Norfolk in what would amount to the 1862 version of a distant blockade, and
Virginia may as well be beached.
See below:
There's also the minor point that Virginia can barely make headway as it is in a flat calm; steaming east from Hampton Roads toward Cape Henry takes her into actual seas, which the USN's ocean-going steamers can easily cope with, but she cannot...
Likewise, steaming north toward the Potomac is unlikely to end well; aside from the realities of the US fortifications on the river, there's the minor point the river simply gets shallower and shallower the farther west or north one travels, and there's a southern-flowing current.
Trying to take
Virginia north up the Bay does little; Baltimore is very well defended, and along with the obvious operational issues, the Bay simply gets narrower and more difficult to navigate, and
Virginia gets more and more vulnerable to swarm attacks by small craft, in less and less water, and with more and more vulnerability to shore batteries and the like - think
Blucher in Oslofjord.
Virginia makes
Monitor's seakeeping abilities look good.
Best,