While touring the SS KLONDIKE and in Louis L'Amour's novel Sitka, I heard references to using beams or poles of some sort to "walk" ships through shallows. I honestly cannot visualize this process since the leverage seems improbable and, bless her heart, the tour guide was just parroting something that she did not understand.

Does anyone here have more details on this walking process? Images would be wonderful.

http://www.earlyblues.com/cb6.jpg ?