Hi Arnold, In installed a CDI furler on my M-17 this spring since I sail mostly single-handed and was attracted by being able to control the headsail size in varying winds without leaving the cockpit. Since with a furler a single sail stays on the boat most of the time, I gave considerable thought to the sail size which would cover a wide range of conditions. It seemed like a large genoa, such as a 150% or bigger would have to be reefed a too much of the time sailing under normal conditions, and I thought it might lose too much shape when reefed down to working jib (100% - 110%) size. Since you would have to use a heavier sail cloth to cover the range of wind conditions, when unfurled as a drifter, you would not have the lightness such sails usually have. I chose a 135% genoa with luff foam made by Elliot Pattison, and this has worked fine for me. Most of the time I sail it unreefed, and when reefed it down to the 110% range (about two or three turns), it retains good shape and still sails well to windward. I have reefed it down smaller (maybe 80%), and it still sails fine. Luff tension is not a problem since the luff tape and plastic foil provide adequate stiffness. I use a backstay tensioner to control the headsail luff shape. The CDI unit is not too hard to install, simple to operate, and seems to be bulletproof in operation. It's so easy to work that you can react quickly to changing wind conditions. Having used it now for several months, I wouldn't be without it. Hope this helps, Rick M-17 #633 Lynne L ************** Get fantasy football with free live scoring. Sign up for FanHouse Fantasy Football today. (http://www.fanhouse.com/fantasyaffair?ncid=aolspr00050000000020)