This "plan" involving the northbound steamer is actually one of the vaguest elements of the novel. A few minutes later Nostromo has changed the plan to meeting the steamer at sea , and later Captain Mitchell says that interception at sea was the plan from the first. How the northbound steamer was supposed to "get orders" is unclear with the telegraph out, but at any rate it never does arrive, at least during Decoud's 10 days on the island -- another instance of total confusion and disrupted intention in the gathering Separatist anarchy.