It seams this topic comes up every year at this time and every year there are numerous posts.
A quick search for steering will show the years of trials and errors.
Anyway, I had the problem one year and installed a grease nut in place of one end nut, pump it full o grease at the end of the year and the next, no problem.
Here's a link for the Davis Lube nut:
http://www.boatersworld.com/product/358500676.htm
Do a search for the nut, cause I think you can get it cheaper somewhere else, even direct from the manufacturer.