Goggles w/ a Permanent Darkvision Spell?
I mean, it doesn't really sound like a problem that needs an imposition as it does a magic item. You could conveniently capture an old, unable to fight mage/craftsman that could create some sort of item for the Players or ship.
Or create a homebrew feat like this:
Pirates Do it in the Dark
Benefit: Your knowledge of ships and experience fighting at night allow you to fight in the dark of night. You receive limited darkvision while on a ship at sea. (20 feet, no benefit on land.)
Kinda clunky, but hey, that's homebrew, right?
Well, by comparison:
"Get up you dogs!" Gives as its benefit a 1st level spell to all crew members for 10 infamy, once per week at the "disgraceful" level.
"Honour the code!" Gives +4 Cha (equivalent to eagle's splendor, a 2nd level spell) to all crew for 5 infamy at the "notorious" level.
For a middle ground, I'd propose:
Despicable Imposition (cost: 10 infamy)
"Dead of Night!" The PCs and their crew gain darkvision for the next 24 hours. This imposition can only be used once per week.