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IS LAST YEAR’S PAINT STILL GOOD?
There are basically two types of bottom paint. The very expensive ones, which we rarely use around here, combine the critter & algae shedding toxins with the binder. As the binder dissolves it continually releases the toxins, therefore if there is paint remaining on your hull it is still viable. However, the more standard paints that we use in this area do not have this feature. They rely on the toxins rising to the surface to be released. After only a few weeks out of the water the paint surface hardens and the toxins cannot be released. So, evidence of paint on the hull is not an indication that it still works. You must either sand it to remove the hard surface or re-coat. Re-coating is usually the quickest & cheapest solution.
The following is courtesy of Don Casey of ‘Boat US’
STRIP?
Remember that the adhesion of the new paint is only as good as the paint under it, so watch for signs of adhesion failure. Anywhere the old paint is flaking or lifting, worry the exposed edges with a knife or small chisel. If the paint zips off, the bottom needs to be stripped.
You may also have to strip the bottom if you are changing the type of paint. For example, the aggressive solvents in vinyl paints lift other types of bottom paints, so if you are applying vinyl, any non-vinyl paint has to come off. And soft, sloughing paints are a poor undercoat for anything other than a fresh coat of the same.
Lay a tarp on the ground under the boat to catch scrapings and paint drips; these should be disposed of in an environmentally acceptable method under the direction of the Marina staff. Using a two-inch hook scraper is the stripping method least injurious to you and the planet, and is often the easiest method as well. If you decide to use a chemical stripper, be sure it is one formulated for fiberglass; regular strippers will attack the gelcoat!
SAND
When the old paint is in good condition, in general you need only sand and wash it, tape the waterline and roll on a fresh coat or two. A grinder loaded with 80-grit discs on a foam pad can quickly prepare a hull for re-coating, but it can also chew through the paint and into the laminate in an instant! If you lack experience with this powerful tool, 80-grit paper in a random orbit sander will do the same job, somewhat less quickly but with much less risk to the hull. Do not use a belt sander; it is designed to make things flat, and that is the effect it will have on your hull!
Many marinas and boatyards now prohibit normal power sanding because of the dust it generates. The solution is a Shop-Vac and a random-orbit sander with a vacuum hose connection. If you don’t want to buy a new sander, slip a length of plastic hose over the dust bag mount on your old palm sander and tape the other end into Shop-Vac hose. Either rig will capture most of the toxic dust sanding generates.- but not all of it. Be sure to wear a tight fitting respirator – not a paper mask – while sanding. Also wear ear plugs to shut out the din of the sander and the Vac.; you’ll save your hearing and find the work much less tiring.
STIR
If the marina has a paint shaker run it for at least five minutes. In the absence of a shaker, pour half the paint into a mixing bucket so you can mix the remaining half vigorously without sloshing paint onto the ground. Keep stirring until the bottom of the can feels clean to the touch of your paddle. Slowly stir in what you poured off until the paint is uniform in colour and consistency. If the paint has been on the shelf for a while, getting it mixed thoroughly can take ten to fifteen minutes, but don’t skimp.
ROLL
Roll the paint onto the hull using a short nap roller cover. Ant extension for the handle will make painting the hull easier and keep you clear of the inevitable droplets the roller will sling! Wear sleeves and gloves to keep the paint off your skin.
Don’t add any thinner to bottom paint unless the manufacturer specifies otherwise. Fill the basin of your paint tray with paint, dip your roller, unload it on the tray slope and roll it up and down the hull from the waterline to the keel. Work fast, as many bottom paints dry quickly. Each time you re-fill the paint tray, first re-stir the paint in the can.
By the time you work all the way around the hull, many bottom paints will be dry enough to overcoat. Check the specifications on the paint you’re using. A second coat lengthens the life of almost any bottom paint. No sanding or other prep is needed between coats. Save some paint for the areas under the stands or trailer pads.
Get the yard manager to move the stands as soon as the rest of the hull is dry. This may incur a charge.
Put sheet plastic on the stands or pads to protect your new paint. Prep the bare spots and apply the appropriate number of coats.
PROP AND SHAFT
You can paint the prop if you like, though it probably won’t stay on for the season. Prop paints are available, but demanding prep – up to four prime coats – discouraging their use. A heavy coat of wax on the prop will keep it clean for a time.
Don’t paint the shaft, and leave all your zinc anodes unpainted. If you are installing new zincs – a good idea – make sure you don’t paint over their mounting locations. Good electrical contact is essential for zincs to do their job!
Let bottom paint dry at least overnight and check the can label regarding getting the boat into the water within the time specified.
1424 Commodore Ln, Box 41, KARS ON K0A 2E0
Tel (613) 489-2747
Fax (613) 489-1486
Email: info@longislandmarine.com
www.longislandmarine.com
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