Ditto any play in the system per Chris above, however, some amount of "wander" is a given in any single screw deep V hull setup. I have had it in all three of my boats with a Volvo drive. Some factors that make it worse are prop pitch and drive trim. Too far out (or in) will make it worse. When set up "as good as it gets", the boat will tend to wander in the direction of prop rotation, then pause and slide back ( as the "keel like effect" of the hull takes over). Thru interitia, the boat will over correct and the process will start all over again. Any attempt to correct this with helm movements almost always make it worse as you are always correcting " too much and too late", so to say. Any amout of cross sea or wind will make it worse. Once the hull starts moving forward fast enough so that the "V" waterflow dominates the prop's crawl ( walk) in the direction of rotation, the problem will stop, however, this speed is usually too fast for some trolling and too fast for marina no wake areas. It's a deep v thing, not a particular drive issue... unless of course as posted above there is too much slop in the system. With my Volvo drive, the "slop" issues occur elsewhere.
When my boat is set up correctly and all is OK mechanically, the wander is about +/- 10 to 15 degrees. If I hold the helm so that the drive is dead straight, the boat wanders back and forth between this arc. Unless I am in a crowded marina, I usually don't have to bother correcting. There is some evidence ( I wasn't paying all that much attention), that dropping both trim tabs all the way down seems to dampen the wander somewhat. I would suspect that different hulls will behave differently. Perhaps dropping one tab and not the other will help??? Once I got used to the wander ( it intitially freaked me out), I just learned to live with it.
