Boat Maintenance

Antifouling for a wet slip, a dry rack or a trailer:

how the boat is stored decides the paint. A boat that lives in the water needs antifouling all year, and an ablative coating suits it: it wears away slowly as the hull moves and keeps working after a haul-out, so the boat can go back in without repainting. A hard paint holds its film instead of shedding it, which makes it the better choice for a boat pulled onto a trailer after every trip or nosed up onto the sand, where rollers and bunks would grind an ablative away. The catch is that hard coats build up layer on layer until they have to be stripped. A boat stored dry and launched only for the day often needs no antifouling at all, just a clean, waxed bottom. Interlux, Pettit and Sea Hawk all make both kinds, so read the label for hard or ablative rather than trusting the brand.

Waterline stains, chalky gelcoat and the polisher:

the topsides are the other half of the job. Run a boat up the mangrove channels at Sierpe or into the mouth of the Tárcoles and it comes back with a brown stain along the waterline and across the bow that soap will not shift; an oxalic-acid hull cleaner lifts it without sanding. Gelcoat that has gone dull and chalky in the sun needs a cutting compound first and a wax or sealant after, and on anything bigger than a skiff that means a machine. A dual-action polisher forgives mistakes; a rotary cuts faster but can burn through gelcoat on an edge in a moment, which is why yards use them and weekend owners mostly do not. Flushing muffs and impellers belong under boat engine parts, and cleats and rails sit under marine hardware.

Used polishers, covers and opened tins:

a second-hand polisher should spin up without a grinding note from the bearing, and the backing plate should run true with no wobble at speed. On a cover the thread usually rots before the fabric, so pull gently at the seams along the top where the sun hits hardest, look for mildew in the folds and check that every strap and buckle is there. A cover cut for one hull rarely sits right on another, so ask which make and model it was made for. With paint, the label matters more than how full the tin is, and a tin with no readable label is a guess. Pressure washers fail at the pump: ask to see one running and look underneath for drips.

Listing leftover paint, a cover or a bottom job:

photograph the label so the brand, type, colour and batch can be read, and say how much is left and whether the tin was resealed. For a cover, name the boat it fitted, with its length and beam. If you offer bottom cleaning, antifouling jobs or detailing, say which stretch of coast you work, whether you haul the boat or dive on it, and which paints you apply. Someone repainting a panga on the beach at Puerto Jiménez before the season wants to know, before making the trip, whether your leftover tins are hard or ablative and whether they carry copper, because that decides whether they can go over what is already on the hull.

FAQ:

• Can I paint new antifouling over the old coat?

  Usually, if you respect the type. An ablative goes over a sound hard coat once it has been sanded, but a hard paint laid over an ablative will lift off with it, so the old ablative has to come off first.

• Is a copper antifouling safe on an aluminium boat?

  No. Paints based on cuprous oxide set up corrosion on aluminium hulls, sterndrive legs and trim tabs. An aluminium boat needs a paint labelled as suitable for aluminium, which uses a different biocide or none.