Aluminium builds superb workboats, patrol craft and leisure hulls, light, strong and corrosion resistant in its own right. Then somebody paints it like steel, and eighteen months later there are pits you can lose a pencil in. Aluminium is not difficult; it is different, and three rules cover the difference.
Rule one: nothing copper, ever
Copper based antifouling on aluminium creates a galvanic cell with the hull as the sacrificial element; the result is aggressive pitting that can perforate plate. Only antifoulings explicitly rated for aluminium go near it, and the same discipline extends to copper bearing shop primers, brass fittings seated bare, and even copper contaminated abrasive. Blast media for aluminium must be clean, aluminium safe grades.
Rule two: the oxide layer is the enemy of adhesion
Aluminium instantly grows an invisible oxide film that paint grips poorly. Preparation means thorough degreasing, then abrasion or sweep blasting immediately before priming, then a thin epoxy primer coat within hours, before the oxide reforms thick. Etch primers and specific pretreatments have their place per the system data sheet; skipping the fresh surface to primer window is the classic adhesion failure.
Rule three: isolate everything dissimilar
Stainless fasteners, bronze gear and steel brackets all outrank aluminium galvanically. Bed them on sealant, sleeve them, and coat the aluminium around them generously. Anodes sized and placed for an aluminium hull, and correctly bonded, are part of the coating system in every sense that matters.
The scheme that works
Degrease, abrade, epoxy primer in two coats, epoxy build where fairing is needed, then polyurethane topsides above water and aluminium safe antifouling below. Familiar chemistry, unforgiving sequencing.
MENA Industrial Supplies stocks aluminium safe schemes in Dubai and answers vessel specific questions the same day via the marine paint page.