While exploring Far Harbor, the Sole Survivor may randomly pick up the Shipbreaker's radio frequency, immediately starting the quest. Provided settlements have been built in Far Harbor and settlers were recruited, any of them may approach the player character to tell them about Shipbreaker, starting the quest as well. Follow the signal to a patch of land near a ruined house to the far west of Eden Meadows Cinemas and north of Briney's Bait and Tackle, where one will find Shipbreaker, a unique fog crawler. Once the fight is over, the player character is prompted to speak to Old Longfellow. He will talk about how he has been searching for Shipbreaker for years. Tell him that Shipbreaker is dead, and the quest will complete with the player character earning Skipper's Last Stand, a unique harpoon gun that Old Longfellow was saving to deal the final blow on Shipbreaker with.
pc If a player doesn't track it down during its original appearance it may vanish with the message "The shipbreaker has moved on for now". It will then fail to reappear and its radio signal will be blacked out even though it will still lead you to the quest location. [verified]
This can be fixed using the console commands on PC. After travelling to where the Shipbreaker should be type in showquestvars DLC03WorkshopRadiantOwned05 to get the Shipbreaker's ID. Then prid whatever the id is. Once this is done it should be showing at the top of the console. Then type disable, press enter then enable and press enter again. Once the console is closed, the shipbreaker should spawn and you can kill it and finish the quest.
The game will sometimes bug and the radio signal will disappear permanently, if this happens you can use the following console commands to find and reveal Shipbreaker: player.moveto xx040c3a, prid xx040c3a, disable, enable where xx is you load order number (normally 03).
pcps4xboxone The location can still be tracked from the radio menu even though it is blacked out. Scrolling down to the location of the radio frequency, will still lead to a location regardless of the quest monster being there or not.
pc The signal will never appear while on the island. Using the command sqs xx040a87 will reveal that the quest is Stopped.
The quest can be activated the following way:
Get Longfellow as a companion and Fast Travel to the north side of the island and travel to where the Vim Refresh power armor can be found.
When at the location enter the following commands into the console: startquest xx040a87, xx040ab1.enable, xx040c3a.enable and exit the console until the signal appears then tune into it.
Enabling Shipbreaker with the above commands will allow it to spawn in it's default location which is slightly north of where you are.
Enter the console again and put in setstage xx040a87 100, this should start the quest and give you the option to talk to Longfellow.
At this point you can talk to Longfellow and then proceed as normal for the rest of the quest.