Weather cancellations are the operator's call, not yours. Lightning within a few miles keeps boats at the dock, and summer storms here form fast. Most companies reschedule or refund for a cancellation they make, but a no-show or a late arrival is usually non-refundable. Read that policy before you pay.
The Atlantic season opens on June 1 and closes on November 30, and August through October is the stretch that puts the fleet on the trailer. A system a long way offshore can stop charters for days without a drop of rain falling on the island. And if the Governor signs a mandatory evacuation order for Beaufort County, nothing sails, and you will not be on the island to take it anyway. Insure anything booked months ahead into that window.
Departure points change. Daufuskie ferry service has shifted terminals more than once in recent years, and small operators move marinas. Confirm the actual dock address on your confirmation rather than the one you read last year.
Summer Saturdays are turnover day for weekly rentals and US-278 backs up badly at the bridges. Leave an extra half hour for a morning departure or you will watch your boat go without you.
No-wake zones are enforced in Broad Creek and around the marinas, which is why the first stretch of any trip is slow. And if you are on a rented boat rather than a crewed tour, the dolphin rules apply to you: stay 50 yards off, no feeding, engine in neutral if they come to you.