Last time we went they charged $4.00 per person for use of the beach. At that time, no there were no chairs, but I did read that they will be putting some on the beach, I'd assume you could rent them if you wanted.
I did a trasport only snorkeling tour for trunk bay last week. We had our snorkeling gear already, so we just bought the transport only form the cruise ship (Norway). That was a mistake! Could have saved $24 at least for both of us. AND we had to leave at 1030 with the group or pay for our transfer back to the ferry (which we had already paid for when we bought the transport only package).
SO.... here is how you do it...
On the cruise ship, go to the excursion desk and buy a ferry ticket for St. John (if you are on the Norway). If you are docked at Thomas, just take the ferry to st. John from there. Once you get to St. John, there will be several "taxis" that will take you to Trunk bay for $4 per person. To get on the beach, I think it is $4. Then when you are done, take the taxi back to the ferry for another $4. Double check when the last ferry is to St. Thomas before you get to Trunk bay.
Christy-you mentioned sign up for ferry ride on cruise ship. We are going Carnival I don't know if they do that, also I believe you can take a taxi at the pier to the ferry which saves times doesn't it.
I am not sure about Carnival. On the Norway, we anchored out in the ocean, so the ferry came to pick up all those with tickets directly from the ship. Since your ship actually docks in the port, then you just need to figure out the easiest and least expensive way to get to the ferry and get over to St. John. I do know that while I was at St. Thomas, there were TONS of taxis taking people to and from the cruise ships that were docked. They were prob. cheap to, because they were the open air truck like thingys, lol.