If I try to lift the rudder arms or tiller cross bar to unlock the rudders it works, but the cams do not rotate so I can not lock the rudders back down without manually rotating the cams first (usually on shore with a screwdriver). Whenever I hit a shallow area, the rudders kick up fine and the cams rotate so that I can easily relock the rudders down latter. Evidently, pulling up on the rudder arm affects the cam differently than when the rudder kicks up after it hits something.
Your signature clued me in to why this is happening - an '82 boat does not have the rake-adjustable castings. It has the fixed rivet/pin in the upper casting that engages the rudder cam when the rudders are locked down.
What's happening with your rudders is that when the rudder is "locked down", the pin is not seated firmly in at the base of the hook on the top of the cam. When you lift the tiller arm, the pin bears against the end of the hook, the hook flexes, releasing the tiller arm, but not rotating the cam.
When you come in to the beach, the force of the bottom pushes the tip of the rudder aft, forcing the pin into the corner of the hook, releasing the tiller arm AND rotating the cam to the unlocked position.
If you put the boat up on wheels or a trailer, you can see this happening yourself. Lock the rudder down, then pull gently aft on the tip. You'll see the rudder castings move relative to each other (slightly) before the pressure on the tip increases significantly.
With properly adjusted / drilled rudders, the castings do not move realative to each other until the cam starts to rotate.
This is easily fixed with the rake-adjustable upper castings; less easily fixed by re-drilling the rudders.