Re: The Coquina Rudder
No such thing as a dumb question. It's how we all started.
You're almost there in terms of visualizing it, you just have to think about carrying the athwartship part of the line further forward, so that there is a length of line on both port and starboard sides back where you will be sitting (the sternsheets). That way, you can grab the line on the side you are sitting on and either push or pull it fore and aft to turn the motion at the rudder into a side to side motion. Here is a picture of such an arrangement with a rudder head bar, but the principle is the same as if the line were lead through the transom and attached to the rudder directly.
In this picture the line seems to be a little slack to allow pushing, but that is easily remedied by shortening the line
"A man who is not afraid of the sea will soon be drowned, for he will be going out on a day he shouldn't. We do be afraid of the sea, and we only be drowned now and again" Arran Islands Fisherman