If the above doesn't work, you can wet sand with very fine grit sandpaper, you can buy 1500 grit and maybe even 2000 grit at AutoZone and PepBoys. Just keep the surface wet and lightly sand, then wash and wax.
Mark, Thanks for the link. Lots of good information. Looks like a lot of work for someone like me without a lot of free time. Can anyone recommend a good boat detailer in the Sacramento area? Thanks.