Three Secrets of Priming Aluminum Boats: Beating Corrosion at the First Coat

One of the biggest questions posed among new boating enthusiasts is often, “How do I make my aluminum hull last a really long time?”

Aluminum tends to be the first kind of boat new boaters acquire as they step into the hobby. Aluminum is light and relatively inexpensive when compared to fiberglass boats of similar size. It’s also relatively fool-proof, but this depends on the quality of paint job and how well the hull has been maintained. Another downfall of aluminum boats are that they can ding easily and tend to be harder to repair. Aluminum, like all metals, can corrode if not properly waterproofed.

A secret of boat painting is that the majority of waterproofing occurs in the first few layers of paint, which is usually the primer. A primer is a paint that’s designed to be painted over a bare (and clean) boat substrate to aid in paint adhesion and water protection. A primer makes the difference between an aluminum boat lasting a season in the water and a boat that lasts twenty years.

The first secret to effective aluminum boat priming is to recognize what tools you’ll need for the job. Priming aluminum begins with buying the right kind of primer. Priming aluminum calls for a zinc chromate etch primer, which stops corrosion most effectively and in several layers, will waterproof the metal. Priming isn’t just about one layer of paint either. The best priming jobs have 3-5 thinned layers of primer applied one after the other. Ensure each coat is completely dry before applying the next, and sand in between each layer very lightly to help aid in adhesion.

 Priming Aluminum BoatsThe second secret to effectively priming your aluminum boat is to properly prep the surface of your boat substrate. This means sanding down areas of rust, completely repairing any dings (hammering them out or patching them) and ensuring your surface is completely clean and dry. 80% of your work should go into preparing the boat substrate before you apply any paint, primer or any other coating.

The third and final secret is to then apply a layer of a what’s called a “chromate conversion coating.” A popular brand of this is called Alodine. A chromate conversion coating stops corrosion in its tracks and should always be applied to bare aluminum if it’s never been treated before. You should do this before you apply the first coat of primer.

Always apply your coats of primer when the dew point is lower than 80 and you have a warm, but not scorching, day outside. Also, be careful that your boat is evenly exposed to light. You don’t want one side of your boat in shade and the other side in direct sunlight, which will lead to different rates of curing and make drying more difficult than it needs to be. Remember, the amount of work you put into your boat upfront will determine how professional your job looks and functions.

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