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So by holding back on the boat say bottom build up will not only slow the speed/ Kts. But your RPM'S also drop by 1,000 or better
I had great results with Trinidad zinc coating spray paint. Paint all underwater metal. I concentrate on the hubs of the props and leave the the outer half of the prop blades bare. They must see higher speeds through water and never get barnacles on the blade tips. I do this because I was told that painting the prop can slow the boat down. I had very little barnacles when I pulled it this year. I am in brackish water in the Chesapeake bay. My shafts use to look like corn cobs when I used bottom paint or bare metal. I only had a few with the zinc spray paint.What is the best thing to use on all metal pieces under the boat I guess it must be bronze my props, rudders, & drive shafts that the only thing that got growth on it the fiberglass was clean