​More like a single spoke wheel, with the ability to easily change it's location and/or adjust the leverage.   The lines run from either side of the blade case through pulleys to a stick on a hinge or socket.  It is light, hard to break/easy to fix, simple to usequick and easy to align and takes up minimal space.  

For harrys, a further advantage is it is fairly easy to change from both rudders turning the boat to either rudder locked and the other steering and to both rudders working to steer the boat sideways, all with the same control.  ​ The thing that makes this possible is the steering lines being cleated on the whipstaff.  

There are a couple of ways to organise the lines.  1) lead them directly to the whipstaff via snatch blocks which can be moved and 2) run a loop off each rudder with lines that tie onto it as and where required.  The bigger the boat, the more likely the latter is to work best.  

I suspect the biggest con with them is the seeming lack of permanence and solidity for one of the more essential parts of the boat.  

Bought some polystyrene today, will use it in the mast fairings.