I would only take a charter boat to USVI if you want to spend a couple days there. Otherwise, I’d just make arrangements to pick them up in the BVI. If you do want to sail to USVI, you will need to fill out a form on sailclear.com, a visit immigration, customs, cashier and immigration again (at Great Harbor they are all 15 feet apart but it will still take about 20 minutes. If your charter boat is registered and has a ROAM sticker you can clear customs once you’re in US waters ( and yes, everyone needs to be US citizens) . I just did this 2 weeks ago. There are some neat places to visit if you want to spend a couple days in the US.