[Llarry]

The final U.S. Navy battleships -- the Iowa class built during World War II -- were built with a beam just narrow enough to fit through the Panama Canal. But with a margin of just a few inches on each side.

Here is a photo of the USS Iowa (BB 61) in the Panama Canal. It's a tight fit!

The capability to move a warship from one ocean to another rapidly is a big plus. Unfortunately, modern aircraft carriers are so large that keeping the beam under 110 feet has proved impossible. With their 130+ foot beam, carriers must take the long route to transfer between oceans.