having read "far to many" threads (recently), comments, stories and documents... over the last 30 years that involved so many people asking questions and wanting answers to antifouling and painting questions i think i can offer some technical / applicator and "layman" views on your issues.
My history, without trying to sound like a "smart arse" has been involved with major marine coatings organistions in the development, testing, manufacture and application of marine coatings. (now Semi - retired
I have also worked with a lot of organisations with regard to developing fast coatings for race yachts, power boats, large commercial ships and hi speed power boats.
I have noticed there is a lot of people confused about what is best for differing boats in differing situations! and a lot of confusion regarding how antifouls work / do not work.
there seems to be some good people with some helpful information on this site (and others) but there is also alot of "misinformation" being spread around (which is probably why some boaties have continueing poor or confusing results, with thier bottom paint inparticular.
If you want the facts and some technical feedback i am willing to help.
But remember the first port of call is with the supplier or makers of the product! especially if the product has failed to perform to specification within a "reasonable time period" .
These guys know thier product best and generally will sort your issue out (if you are honest with them) but remember there are many good professionl applicators who are only to willing to help out and give a second opinion.
But one very good tip for any body who buys any paint...
The higher the Volume solids (the amount of paint minus the diluant / thinners) the better the product. So ask for the data sheet and compare!