Hi sorry for delayed response to this. The idea was to be able to automate a submarine to bring up quantities from the trench once the tin in the sandstone wasn't enough anymore. However, I only tested this in a sandbox game, so there's a possibility there's a soft lock or logistic issue I didn't notice?
I'm almost to Maraxsis in a playthrough that's been stalled out so I'll be trying it in a real game sometime.