I carry a 21 foot tandem on the port rail in the 'stirrups' that others have described. We rarely do anything port to but when we do, we just flop the kayak onto the walk around deck for that period we need access to the port side (washing the boat, going into the slings). The 'stirrups' fold in flush. Since we have these hangers up toward the bow we can dock to port with or without moving the kayak.
Picture below is from this weekend when we anchored in Eagle Harbor and kayaked in to have a bite at Docs. Took the shot with a phone paddling back out. As you can see, the dinghy sits quietly on the cabin top waiting for us to return. The kayak in this type of hanger is far more convenient for these short jaunts in good weather.
To Eric's point about boarding: I guarantee you we are not young and we are not gymnasts, but if you look at the picture you can see a side gate open and we bale over the gunwale there and into the kayak with no problem. Just ahead of that gate if you look close you can see the two hangars waiting for the kayak to be dropped back into them. With the kayak weighing about 90#, that is a bit tough to do single handed though I have done it and will again. With the two of us, easy with a rope on each end. I really like this set up and think we might use the kayak less if up on the cabin roof.