That is all you need. I've read to keep a check on the clamp to make sure it doesn't vibrate loose. I wouldn't get a bigger model for a gheenoe. The wt. limit is 6lbs for the ball but I really doubt that you will even need 5lbs. except in the summer. I haven't used them but the only complaint I've heard or read is about the loosing up of the clamp. A little medium strength Locktite thread locker should solve that problem. You may want to get a couple of sizes of cannon balls; one for shallow water and one for deep. I would go with a 5lb weight and see if it was worthwhile to get a 3 for fall thru spring. With light cable and light line you shouldn't need as much weight as you would with the bigger cable on a standard size downrigger.