Undock vs Decouple

[mdkendall]

Sometimes when I click on a docking port the menu offers me "Undock", and other times it offers me "Decouple Node".

There doesn't seem to be any rhyme or reason to it. Screenshots below show the exact same two things docked together in the exact same way, and I am clicking on the same docking port of the pair. Sometimes it says one thing and sometimes the other. It's consistent in any given situation, but if I un-dock and re-dock, or just recover and re-launch the craft, it may be different next time.

Do these two menu options do exactly the same thing (they seem to), or is there a subtle difference I am missing?

Also, "Disable Crossfeed" is only offered on one of the pair, and I am never sure which one its going to be, but it doesn't seem to be directly correlated with Undock vs Decouple.

Edited September 1, 2014 by mdkendall
Answered

[EdFred]

Does one of them show up after a docking has taken place vs an initial separation?

[OrbitusII]

Undocking is between two docking ports and only works if a docking port is connected to another docking port, whereas decoupling a docking port works similarly to a traditional decoupler and will forcibly detach from virtually anything.

It shouldn't matter which one you use if you're connecting docking ports, but if you attach something else to a docking port you'll only have the "Decouple Node" option.

Edited September 1, 2014 by OrbitusII

[mdkendall]

Does one of them show up after a docking has taken place vs an initial separation?

On the particular thing I am testing on the runway right now, yes. Immediately after launch it offers "Decouple" on both ports. Subsequently it offers "Undock" on one port (always the same one) and neither option on the other.

[Taki117]

On the particular thing I am testing on the runway right now, yes. Immediately after launch it offers "Decouple" on both ports. Subsequently it offers "Undock" on one port (always the same one) and neither option on the other.

This is because when the docking ports are connected in the SPH (or VAB) they act as a decoupler, when you undock and then dock them again, since they have already been disconnected they are now docked, and the option is to undock.

[O-Doc]

If you're setting up action groups you want to use decouple.

[Claw]

Yes, what Taki said. Also, when docking ports have the "decouple" option, it does not apply force when decoupling. These options show up differently because the game tracks the behavior differently. (Which actually comes in handy when fixing docking ports.)

Anyway, as a side note, you can mount all kinds of things to docking ports and they provide a clean decouple for the thing that is decoupled. (They don't leave those unsightly spiders hanging off the side of your probes.)

Cheers,

~Claw