Many countries do indeed have the 6 month rule. The BVI does not. The problem however can be a gate agent who does not understand the rules however if you are flying into STT it’s irrelevant since a passport is not required and the ferry companies know the rules.

“You will need a valid passport, with validity covering the proposed duration of your stay to enter or travel through the British Virgin Islands as a visitor. See below for further information on travel documentation.

Entry to the BVI by air is through the Terrance B. Lettsome International Airport, Taddy Bay International Airport and Auguste George Airport. You can enter by sea through the Road Town Jetty; Soper’s Hole Dock, West End; Great Harbour, Jost Van Dyke or Spanish Town, Virgin Gorda.”