Yes, single line to the cockpit. The cable goes up through the cabin in a pipe, comes out of the cabin top and makes a 90 degree turn outboard through a block, then another 90 degree through another block toward the cockpit and ends at a cleat at the aft end of the cabin top.
What do you use to attach the line to your CB?
A knot or an eye splice?
The line has an eye splice, and then a shackle, which goes through a hole near the trailing edge of the centerboard. I bought the line/shackle from Rudy at D&R Marine.
DR Marine Product Detail
It sounds like you need a much longer line than I do though. I looked quickly on Rudy's website, and he doesn't have an Oday 30 centerboard pennant pre-made. However, I bet if you give him a call, he can tell you exactly what you need. In case you didn't know, Rudy worked for Oday for many years, and now owns the molds to some of the boats and their components. Rudy is quite the Oday guru.