Just to clarify Bob's post, the "up" line is only cleated when you are not using an Island which has the new "straight up and down" rudder, and you don't want the rudder blade falling down (in this position the rudder looks a bit like one end of a Venetian gondola
The old "twist and stow" rudder fitted to earlier AIs (and most other Hobie kayaks) just lay on the deck when not in use and didn't need the "up" line cleating.
As you can see, pulling the "down" line very hard is advice coming at you from all sides... the reason behind this is that the rudder blade (when down) has some area which lies forward of the rudder pin axis, and water pressure on this forward part partly counter-balances the pressure of the rear of the blade, reducing steering effort. If the "down" line is not cleated tightly, the blade can swing back slightly, so that the counter-balance area now ADDS to effort on the tiller rather than subtracts from it; a classic lose-lose situation.
2012 Tandem Island "SIC EM"www.scenefromabove.com.au