Scott Christian
Hero
I think all these are plausible, especially for an experienced DM. I don't think anyone that is saying no is advocating for something different. They are advocating for when circumstances dictate that the background feature will not work.What I would do is, if the player said "I want to find a ship to sail on and use my background to help me do so," I'd say something like, "how are you doing this?" Then one of the following may occur:
One: The player may then say they're going up to the captain or first mate and trying to use their nautical knowledge to sound impressive. That's a Persuasion check. (Someone who does not have the sailor background or at least proficiency in sea vessels would have a higher DC and/or obviously wouldn't be able to use their proficiency bonus, or may have to roll Deception vs. Insight with a bonus for the captain).
Two: The player may tell me that their cousin Two-Eyed Bob the Sailor once manned a ship that docked in this port often. There would the above-mentioned Persuasion rolls, but with an added wrinkle of me getting to decide how the ship's crew felt about Two-Eyed Bob (colored by whatever they've previously said about this cousin--and if this is a brand-new cousin they just invented, then I get to decide[1]). I might roll a die and decide whether they liked him based on the result (like, the higher the number, the more they liked him). In which case, there's a chance of backfire. I would allow this for non-sailors as well, but probably with penalties to the roll.
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[1] This also depends on how out-of-character Two-Eyed Bob is. If the PC had said they come from a line of sailors and pirates, then OK. Two-Eyed Bob is plausible. If they had said they had run away from the farm their family had been working for generations to become a sailor, I'd say, "yeah, no, that's totally contradictory to everything else you've said. However, I can't imagine any of my players actually trying to pull this. Everyone at my table is a reasonable person.
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Three: The player may tell me that they worked on a particular ship that docked here. In which case, we have a conversation about the ship and why they left it. This may involve them inventing some details (probably in the form of noodle incidents) that had previously never come up.
If they had previously established that they only sailed on the Inner Sea and they were currently on the coast of the South Sea, then we'd have to have some discussion about how that boat got from the Inner Sea and the South Sea. It's entirely possible that we'd then establish a new fact about the world (a connecting river, a canal, something else). It's also possible that the player would realize there was no way the ship could have moved seas (see above re: reasonable players).
IME, these sorts of conversations take maybe 5 minutes or so, 10 max, which is not an unreasonable amount of time and is certainly far less time than we had to pause the game yesterday when it was interrupted by Toddler Surprise Attack (did you know that if you put your hands over your ears, it works just like daddy's headphones and you can hear what all the other players are saying?)
Four: If I felt like it, I could just have the ship they used to work on, right there in dock. How did it get there? Good question! Want to get on and find out?
I know everyone likes to throw the big-bad DM argument around, but in my experience, they say yes on a 10-1 ratio of saying no. When they say no, I assume they know something I, as a player, do not. Those "no moments" are warranted under certain circumstances. For some DMs, it might be because the players are on a different plane of existence. For others, it might be because they already have the port detailed and the player request doesn't match. For others, it might be because they took other consideration into play, such as pirates or a blockade. And for others, it might be because the PCs already used this contact three times, and the DM had a plot point, where the PC finds them dead because they were "found to be shipping messages."
But in most D&D ports like Neverwinter, Baldur's Gate, Luskan, Waterdeep, etc... I don't think any DM would care. And I don't think the people arguing against this would care either. People care when there are exceptions.