If you were out for a "day sail" from St Thomas to Francis Bay and take some long upwind tacks, then in just 15 minutes it's very easy to stray 2+ miles into BVI waters - while still remaining well outside their 'Exclusion Zone' - as you head towards Little Tobago and Great Tobago Islands before tacking back toward St John. I could see how one could let it happen if you weren't aware of the BVI territorial waters lockdown, or perhaps thought that the UN Convention on the Law of the Seas (UNCLOS) permitting Innocent Passage in territorial seas still prevailed.

I was sailing in the USVI's for three weeks from mid-Oct to early-Nov, and ventured over the border by a hundred yards or so on a couple of upwind and downwind tacks. However, I was very conscious of the 'surveillance' vessel (i.e. inter-island barge) anchored off Great Thatch Island as well as the British frigate observed on several occasions patrolling the waters between Norman Island and St John. I did not try to push my luck or get into a UNCLOS dispute with a BVI border patrol.