Don, in the great lakes there is very little current, there is current under the mack bridge, and other areas, not much though. The wave are tight, even on a wide beam and good captain, you will be a rockin when entering water. once in you can pretty easily swim to bouy, anchor line.
To safely giant stride, a lot of times you jump in, then put fins on. so actually like all diving, GL's divers are very quick to put fins on, within 30 seconds.
With a nice platform on back and good handles, problem is with fuel cost, not many boats like that. Mostly 30+' with little door, or roll off. With a boat in a bad position, 3 wave, you got water in boat 6 waves your sinking, 10 waves, your boat ins now a dive site, Known as a great lakes wreck dive.
So they actually have three ways to enter the water.
Now for long deco I can can sick if I watch the line it goes up and down, constantly. A good mooring buoy is great thing, yet they are lost and a lot or work.
Best diving in the world and lucky to get three good months, and to get a good day.
Don go there and dive, you meet divers at boat launch, and you wait till captain says ready to go, sometimes you meet tomorrow.
There are others that go, and they are more than likely on this board and no how to handle most times of weather, but are not taking paying customers.