ekul246, I started kokanee fishing with these Scotty portable downriggers. I had 2 of these until we upgraded and I loved them because they got me into downrigger fishing for kokanee. I used a 3lb ball and had this exact clamp on model. If you're in our Facebook Group, Kokanee Fishing BC, or YouTube channel, Fougere Family Adventures, you can see them in action in many videos and story posts with photos.
The downside to them was I had to crank down the downrigger to depth (but not a huge deal). It got tiring when reeling down and up with two manual downriggers some days. They also loosened a few times on me, but again not a huge deal as usually a second tightening kept them tight the rest of the day.
I highly recommend these as a cheap way to get into downrigger fishing for kokanee.
***NOTE*** check out Scotty rod holders. I have a few different versions and love them. The spinning/baitcasting rodholder is very versatile. I also use the Scotty fly rod holders when fly fishing. This year, I'm trying the Scotty rocket launcher rod holders. Combine one of these rod holders with the Scotty Oar Lock mount and your fishing trips will be more enjoyable.
Here's what the oar lock mounts look like:
http://scotty.com/product/no-248-oarlock-mount/