On Sun, 13 Jan 2008 16:50:29 -0500, "Eisboch" wrote:

Even large, welded steel ships have expansion joints built into the hull
structure to allow for flexing, otherwise it would crack in half in rough
seas.

I saw a documentary on the Britannic, sister ship to Titanic, about
this very thing.

One of the more interesting aspects of the Titanic sinking were the
expansion joints. According to the documentary, the type of joint
used on the Titanic contributed to the diaster - I can't remember all
the technical details at the moment, but it was a type of joint that
was a "floating" joint. After the diaster, the Britannic was modified
to eliminate the the "floating" joint in favor of a boxed type joint.

Oddly, that type of joint contributed to Britannic's sinking when it
struck a mine off Greece in WWI.

It was pretty interesting.