Trapeze wire lenghts should be 16 ft, 9 1/8". The ends do hang above the deck, because the entire trapeze assembly includes shock cord and lenths of trapeze adjustment line (you can see how it is set up in the parts manual).
The trapeze adjustment line, which attaches to the dogbones or J&H handles on one end and the shock cord on the other, are 3 ft, 6" and are threaded through the thimble at the end of the trapeze wire. it has an adjustment stopper on it that allows you to determine how low you want the handles to go when hiking out.
The shock cord goes underneath the trampoline to the trapeze on the other side of the boat.
I hope that helps!
BTW...all the Hobie 16 line and wire lengths can be found at
http://www.hca-na.org/