I kinda like the idea of leaving some of the planks out and testing the troops’ tight-walking skills. :D
Btw, I’m fascinated by that spoked cylinder-ish shape near the back of the first boat, vaguely like a face-planted ship’s wheel. Winch, maybe…?
Capstan https://en.wikipedia.org/wiki/Capstan_(nautical)
The bars are removed from the head and lying on the deck around it.
Removing the bars is for safety once it has been turned and the line it holds is under tension. If the locking mechanism slips and the line starts running out, the capstan head would be spinning very fast and the bars would be a hazard. The bars have been left out on the deck (rather than stowed away) so that the capstan can be used again quickly if needed. Probably in this case the capstan is being used to tension the lines holding the bridge.
