Beautiful bottoms
With the start of the boating season looming over the horizon, it’s time to wake up your pride and joy and get her ready for summer. Giving her a clean bottom is a good start.
Boats which remain in the water suffer from the growth of marine organisms on the hull. At best these slow the boat and increase fuel consumption. But they can cause permanent damage to the boat’s running surfaces and its mechanical components. The solution is anti-foul. Its technical name is biocide, and numerous products are available (see sidebar).
Because anti-fouling paints contain active ingredients which lose their effectiveness over time, renewing the paint is perhaps the biggest regular maintenance task facing a launch or yacht owner. It typically needs to be done every 12 to 18 months, although longer-life products are available.
To see the effect of anti-foul, we ran some performance tests on our project boat which had a heavy growth below the waterline. At cruising revs she was only making 13.5 knots, with maximum speed less than 16 knots. The guys at Pine Harbour Marina organised a haul-out, water-blasted the hull and returned her to the water. We averaged 17 knots at the same RPM, with a maximum of just under 22 knots. Better, but still off what was achievable.
We again scheduled a lift and some hardstand parking space with the marina. Anti-foul paint is not good for the environment so a containment system is needed when cleaning off the old product. A common solution is to wet-sand the old surface, with a special drain collecting the runoff. Most marinas have a special area for this purpose, with a holding tank for the contaminated water.
But the underside of the boat was in such a bad state that we first called on the specialist advice of Warwick Heany from Pine Harbour Boat Painters. He identified areas of earlier shoddy workmanship, including epoxy patches applied over layers of anti-foul.
The only sensible solution was to do the job properly, with a complete scraping of the hull followed by sanding back to the underlying gelcoat. After this an epoxy primer could be applied, followed by the new anti-foul paint.