I remember Mark Toland recommended getting the short booms for downriggers on a 16'er. I think the ones I put on were 20" scotty's. The shorter booms are a safety factor where problems could arise should a ball get hung up. I did lose some, but never experienced anything more than a small shudder on the boat. Having the longer booms will cantilever the forces out a bit more, don't know what the limits are though.