An automatic shutdown system that shuts your engine off if the fire extinguisher is discharged. The size of the fire extinguisher is determined by the volume of the engine compartment assuming it is empty.

I just went through all this for my boat. The automatic shutdown system from fireboy cost more than the extinguisher. Incidentally, I sized my extinguisher for twice my engine room volume. The automatic shutdown system on my boat shuts the engine off AND shuts off the engine room blowers if they are on