I also have a bit of steering wander when at very low speed and I wonder if this could cause that also.
I'd have thought not - at slower speeds, it's so small that there just isn't going to be any hydrodynamic significance to it, I'd have thought. Ours always wandered a bit, but much less than other boats of similar size/type etc. Interestingly, if steered dead ahead by the helmsperson, a passenger could almost steer the boat by running from size to side to induce a bit of list. It was nearly impossible, but could be done! (To anyone who saw us slewing all over the Itchen on the way back in - you now know, we weren't blind drunk we were just trying to steer!)
Is this specified in the manuals
Hmm, I've tried to find where I once read that. There's a lot of talk along similar lines on various other forums, but no actual Mercruiser 'advice' as far as I can see. I've got a funny feeling I may have read it on the website for the shop when I bought a replacement. Doesn't mean it's right of course though!It seems its horses for courses though, as some people with power steered boats seem to benefit from a correctly set finned anode.