IanJ, which Hunter 31 do you have? One from 1984 to 1987, or one of the newer 310's. It does make a big difference. I have a new bimini on our 87 Hunter 31, and would be glad to measure it up for you.
I have a 4 bow that comes from the transom, up to just over the companion way. It does come very close to the boom, but doesn't touch while sailing.
There is another one I have seen in pictures that looks just like mine, but only comes up to the end of the boom. And this one only has a main bow with 2 smaller ones forward. Almost like a front porch. This one leaves alot of room in the cockpit area to move around in. That is what I am looking for.
The kind I have is desired here in the midwest due to less wind to sail, but more shade at anchorages. I will try and dig up a picture and send to you.