I have considered a camleat for my CB lines, On the DS II (for those who don't have one) there are 2 lines (well, actually it is a looped line) to control the CB. One pulls the cb down, the other pulls it up. When sailing one usually cleats the downline to keep the CB down (unless in shallow water, when the line needs to be free to allow the CB to kick up) the standard cleat is, as Barry says, a standard, horn cleat (not a jamcleat, you DON'T want a jamcleat since it could.....well, jam.) and the same cleat is used to tie off both lines.
I have thought about switching ot a camcleat, but with that...if I get into shallow water, there may be too much tension on hte downline to be able to release it. I discussed this with another DS owner (he actually had a DS III) and he mentioned a camcleat that will release at a preset pull. It would hold the CB down, but would release if I hit bottom. I never got to look into that yet (was out of work at the time, no $$) but it is a possible idea.
My other thought (still has the problem if I bottom out) is a double camcleat, these have 2 camcleats in tandem, 2 swinging cams that press against a single fixed post in the center. The Harken 412 is one (not cheap! $85.00, I guess that is why I never converted to that!).
I have a good way of tying off my CB lines, hard to describe.....easy to do. If the CB is all the way down, I loosely tie the downline ot the cleat to hold it down. If the CB is partway up/down, I tie off the up line first, then loosely tie the downline on top of that (same cleat) that way if I get into shallow water and the CB hits, I can simply release the downline and it can kick up. I moor the boat with the CB slightly down, I raise the CB until the block on the up cable is about 9" aft of the mast (Cb is then hanging down about 12-18") and tie it off. I then snug the down line to keep the CB in that position and cleat it off on top of the up line. (If you have a DS II or III, you can picture this, if not...sorry!) I find that my boat sits better to her mooring with a bit of CB exposed.
While sailing, I find that I will tie the downline to the cleat by wrapping hte line around the aft (or lower) horn of the cleat, then around the forward side, then twist the line to hitch the line on hte aft horn. (I think? writing this from memory....... will have to visit my boat to really tell ,and the CB is out of the boat with the lines unrigged at the moment!). I'ved included a picture........not sure if it helps. (I color-coded the lines to clarify) I don't fiddle too much with CB adjustments, one reason is that while sailing the side pressure of the water tends to lock the CB in position, so I need to round up into the wind and let the pressure release bevore I can move the CB. That is more cumbersome to me than hte cleating arrangement.
I've also included a diagram showing the 1977-85 DS II centerboard control lines for reference. (helps non-DS II owners understand our boats)