I am not an expert, but clearly pilot boats must be built to take a lot of punishment. And they don’t have the mass to damage the big ship beyond the paint layer.

I agree that it seems that must be the case. I'm just curious where my assumptions break down - whether I'm overestimating the mass of the pilot boat, overestimating the force a single perfect wave can impose, or underestimating the thickness of these ships' hulls.

I've just always be impressed by the amount of energy that boats impart when they collide with anything. Like in this case, the entire bridge was brought down by a collision at under 8knots. Obviously that ship had orders of magnitude greater mass than the little pilot boat, but presumably you want to avoid even dinging up the larger ship, and so that's an orders of magnitude smaller goal as well.

Well, here’s a story to give you an idea. In November 2018, a frigate collided with an oil tanker on the Norwegian coast. It was only a glancing collision, involving the starboard side of the frigate and the bow of the tanker. The frigate was severely damaged, basically having much of the starboard side ripped open, and it eventually sank. You could hardly see any damage to the tanker. (Luckily, or perhaps miraculously, no one was killed or seriously injured.)

Back to the pilot boat: Steering one in heavy seas when trying to deliver or recover a pilot is clearly a difficult art. But at least in the videos shown, there doesn’t seem to be much of an impact between the vessels. I am sure that is in part due to the skill of the steersman. Besides, I am sure the pilot boat will have permanently mounted fenders all around.