Unknown cable

[marioxp]

On the rear port side cabin, above the muffler I found one cable that was disconnected.

Does anyone have an idea what the cable could be?

It probably served something but was replaced with something else.

On the right side are three similar cables, one for the throttle, one for the gearbox and one for turning off the engine.

[Yngmar]

Morse cable, normally used for engine and gearbox control. It's not unusual to put the spares parallel with the in-use ones, but it is unusual to put them in the rear cabin.

Perhaps it was for a remote fuel shut-off from the tank? Where does the other end go?

[Happysailor]

By the looks of it, I assume it has been the previous stop-cable. In the picture you see the thread where it was connected to the engine's stop lever and has the space to travel sufficiently to stop the engine. On our previous boat I once had to replace this cable and this looks like VP original...
Like Yngmar suggested, see where the other end goes to...

[marioxp]

I don't know where the other end goes.
I should have looked right away, but I was in a hurry and had other work to do, and now I'm 350 km away from the boat.

[elias]

Hi , technicians around my area leave one ready to be installed in case the current fails.

[Keweetoo]

I have one of those. It was a mechanical engine stop cable (pull lever by the morse control). When we replaced the engine and a new control panel with push button stop it became redundant and left in situ.