I've gone by inside, without too much issue there. I can't say I've done the entrance though. I've been in and out of Ossabaw sound a ton without too much trouble. Based on the chart, Ossabaw looks worse. The big ticket with any of those is to make sure you don't have wind against tide and waves stacking up. That way you can take it slow as you pick your way in there. Good luck. It's beautiful and remote down there.