My outboard-powered boat stays in the water for 8 months per year, in the Northeast, US. Its is docked on a brackish creek, flowing into a saltwater bay. Runoff from agriculture and residential fertilizers combine with the freshwater-saltwater mix to create a fecund environment in which marine life thrives. As a result, I need to protect my outboard's transom/swivel/tilt assembly from barnacles, weed and slime. I also need to coat my trim tabs, and the hull-mounted strainers for some raw water intakes, with antifouling paint. For the 2015 season, which totaled 214 days, according to my logbook, I used Pettit Alumaspray Plus to prevent fouling on these components.
Alumaspray Plus is an aerosol that can be sprayed in temperatures down to 40-degrees F. I appreciated this characteristic on the chilly March day I chose to apply it. Two coats are recommended and so I applied the first coat in the morning and the second coat in the early evening. ( Dry times are much quicker at warmer temperatures). Personally, I like to apply three or four coats of antifouling to sterndrives, trim tabs or any part that is subject to the " washing" action of water when the boat is underway.
Application was over clean, sound enamel paint, lightly scuffed for the outboard bracket, and over clean, " scuffed bright" stainless ( trim tabs) and bronze ( through-hull strainer). The zinc was removed from the outboard bracket and its mounting boss was masked to keep it clean. Pettit offers "120" special thinner for clean-up. I found that mineral spirits worked fine.
I use my boat several times per week, and so, the tough fouling conditions at the dock, are somewhat mitigated by the boat being in motion and "self-cleaning." Use has as much to do with antifouling performance as location.
So, how did Alumaspray Plus perform? I monitored the coated areas weekly, and its my habit to go overboard once a month with a mask and fins and check the condition of paint, the hull and fixtures anyway. I did not notice any growth at all on the through hull fitting, and on the trim tabs there was just a slight coating of slime on top of each tab--where the washing action of water is nil. Similarly, the outboard's transom assembly sported just a light layer of slime by late in the season, and one barnacle living inside an unused mounting hole.
In conclusion, Alumaspray Plus delivered terrific season long performance. Had I bothered to scrub the coated components, which is good practice and which I purposely neglected for purposes of testing, I'd bet there would have been zero fouling in evidence.
Alumaspray Plus is an aerosol antifouling paint specifically designed for
use on aluminum outdrives and outboard motors without the need for a
barrier coat. Alumaspray Plus contains no TBT or copper compounds, and will not cause galvanic corrosion. Its self cleaning, copolymer finish
washes away at a controlled rate when in contact with water. This process constantly exposes fresh biocides and eliminates paint build up.
Alumaspray Plus’ offers superior resistance to all types of fouling in both
fresh and salt water. It may be hauled & re-launched without re-coating.
For specific application instructions and safety data, please read this document.