Tom - I live on Terry Ceia bay. Marlow Yachts is located on Terra Ceia, and all of their boats, up to 96', make their way into the bay and to their docks along the Snead Island cut. Their boats in the 65-78 foot range have minimum drafts around 4.5'+. Yes, they do need to watch the tide, especially for
winter lows when the
wind has a north component, but that applies to everywhere in the Gulf. There is a great anchorage NE of Bird Cay with 7-9' of
water and good holding.
The channel into Terra Ceia is winding, but it you follow the
charts carefully you will stay in the deep
water. The mistake most people make is that they miss red marker #12 just SW of Bird Cay; it is important to go around it (to your starboard)- passing between the mark and the island, and then go to green #13, keeping it to your port.
Terra Ceia is a wonderful anchorage. Peaceful, undeveloped, and undiscovered. If you have a
dinghy, you can take it through the Snead Island cut, into the Manatee River.
Hope you make it there!
Greg