It was not that long ago where none of the better BVI boat operators would rent you a boat from early July until October at the earliest. Today the insurance rates have been jacked up to 2% of the insured value and the insurance markets are willing to take the risk at that rate to get the business. There are very strong historical reasons why none of the major Caribbean visitor events are scheduled after May 1st. Yes, the rates are less and the crowds are different but your trip can be washed out from any direction anytime after April 15th.