The only specialised marine publication in Oceania that focuses on the maritime industry, from super yachts to small craft to large commercial ships, including coastal shipping, tugs, tow boats, barges, ferries, tourist, sport-fishing craft, je
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Heavy old antifoul causes drag and costs money This hull is overdue for a blastoff Poorly protected metal will quickly foul up costs? Once you decide to go ahead, you can contain your costs even further by timing your survey to take advantage of low slipping fees over the winter. Then take professional advice from a paint supplier about which replacement paint system will perform for two years. Have the work priced before work starts. After slipping the boat, determine whether the existing paint system is still well adhered (ie, no cracking, peeling or delamination is present) and has a smooth surface. If any surface defects are present, the only successful way to eliminate them is to totally remove the existing paint system. Removing the old system has another benefit, as the surveyor can see the substrate and assess its current condition. If the owner intends to sell the vessel within the two-year survey period, a surveyor's certificate with photographs will help prospective buyers confirm their purchase of the vessel. An added benefit if you intend to sell the boat is you can have the vessel brought up to survey standard and/ or any defects attended to before applying the new paint system. Completely remove the existing paint system back to the substrate or to the primer that has sealed off the substrate, assuming it is in good condition. The cheapest way to remove an old underwater coating system is to sweep-blast with an appropriate blast medium. C-grade garnet, bicarbonate of soda or ultra high-pressure water jets are a few of the recommended options. The contractor must take care and be highly experienced, so ask the slipway operator 80 NZ WORKBOAT REVIEW 2012 to recommended a suitable contractor to carry out this work. Check for any potential disturbed water flow areas, such as athwartships weld beads, hull plating fairness issues or disrupted water flow to the propeller. If these areas can be faired or reshaped, this will go a long way to smoothing the water flow. Once this has been completed, your vessel is ready to receive the new paint system. The paint supplier should provide a written specification for a system a professional painter will apply, or a suitable paint system the boat owner can apply himself. A primer or undercoat will be necessary to make sure the substrate is protected. Choose an antifouling system capable of performing for the entire two years under the conditions in which the vessel operates, and which is compatible with the substrate; eg, an aluminium-friendly antifouling for alloy hulls. The paint company will make these recommendations. A minimum of two coats of antifoul will be required and a good idea is to use different colours to see the wear rates on different parts of the hull at the next slipping. It will need to be applied to the correct film thickness, as recommended by the supplier. Also, ensure the new coating system is applied with a smooth, even finish and cures dry and hard before the vessel is relaunched. The paint manufacturer will make these recommendations. Once the vessel is returned to the water, record the engine revs to achieve your cruising speed and have these logged. Your vessel's speed may increase because of the smooth underwater paint system and fuel savings should be apparent immediately. Altex Coatings offers a free technical service that includes on-site service inspections and written repaint recommendations. Ring 0800 258 390 or email sales@carboline.co.nz COMPANY PROFILE