In the event of the pendulum striking anything floating in the water, the whole gear is forced out hinged at the mount (the socket pivots in the mount). The pendulum is held down in the water by friction in the socket. Once the obstacle is passed, the pendulum can be pushed down (to a buffer stop), so that the wind vane continues working as before.
The Hebridean has been tested and is capable of pulling 300 kg force on the lines to the tiller without damage. At this level of force on the lines to the tiller the pendulum may lift itself out of the water altogether. A weak link in the lines that breaks at a much lower figure (100kg) is advised to protect the mechanism if over-loaded.
A line attaching the wind vane to the boat is recommended so that you cannot lose it overboard when mounting or dismounting the gear at the stern.
The lines to the tiller must connect in such a way that they can be released quickly in emergency to steer yourself out of trouble by hand. The common way is to have a chain (that connects to a slot to the tiller) of about 40cm long between the 2 ends of the lines. Connecting to different links in the chain alters the wind vane set-up.
Personal safety has to be a priority when mounting the vane while sailing. The same is true for changing course at the vane base. The wind vane is no substitute for keeping watch.