I put this on 3 years ago (3 coats):
Very satisfied. Now I am getting hard growth only on the bottom of my lead keel. Not really sure why, but all the paint has come off just on the very bottom of the keel, which then allows hard growth. Need to use metal scraper to remove. I would imagine with monthly cleanings, I could get 2 more years (but plan to haul out withing 6 mos to do some drive line work). Next time I plan to put 5 coats of this on and prep and prime the underside of the lead keel better.