Q: I can't control my boat in reverse! Is there anything I can do about this?
Prop walk is also referred to as torque (which is gyroscopic precession). It is one of those facts of life that a C-34 is going to "back to port" (like all single engine boats with a right handed prop). The most important thing is to know it is going to happen and factor it into your maneuvering.
Some of the problem may be corrected by technique. Inboard boats tend to crab to port when backed. The problem is that you have no steerage until there is water flow over the rudder. The worst condition is at idle, because the prop is crabbing and there is little or no flow over the rudder to establish steerage. The technique that I have found to work best is to accelerate fast (near full throttle) in reverse (i.e. put it in gear and throttle up quickly), until good reward motion is attained, then quickly back off on the throttle and shift the trans to neutral. The forceful reverse action gets the boat moving before severe crabbing affects it. Stopping the prop eliminates the crabbing tendency and water flow over the rudder provides steerage. The momentum will continue to carry the boat in reverse, and positive steerage with the rudder is regained. It takes a little practice, but I find that this technique is the best way to back with as little crabbing as possible and you can even turn to starboard. Just make sure you are clear behind before starting this procedure.
A three-bladed prop does wonders for reverse control. In my C34, equipped with the stock 2-bladed prop, backing up was out of the question -- even with adequate power, there was not possibility of backing straight. I just installed a three-bladed 15 x 10, and it's a revelation -- straight as an arrow in reverse. Note, though, that all bets are off if the prop gets fouled by barnacles... by the end of the season I was worse off than ever in reverse.