We don't have synonyms for pinnage yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are pinnate, pinnace and pannage.
(n) :
(Scotland) Obsolete spelling of pinnace. [(nautical) A light boat, traditionally propelled by sails, but sometimes a rowboat, and usually serving to carry messages among the larger ships of a fleet.]
(n) :
(Scotland) Obsolete spelling of pinnace. [(nautical) A light boat, traditionally propelled by sails, but sometimes a rowboat, and usually serving to carry messages among the larger ships of a fleet.]