How to Attach Zinc to an Aluminum Boat

If your aluminum boat has an outboard motor or hangs around where other boats have outboard motors, it needs a zinc. Adding a zinc -- a sacrificial anode -- to an aluminum boat prevents galvanic corrosion of the aluminum. When in the water and in close proximity to harder metals, the zinc corrodes faster than aluminum. It acts as a wall against corrosion and is also cheaper to replace than the boat, even if you must replace it yearly. To replace or install zincs, your boat must be out of the water.

Things You'll Need

  • Zinc
  • China marker
  • Putty knife
  • Clean rag
  • Acetone
  • Drill
  • Adhesive marine caulk
  • Thread locker
  • Adjustable wrench
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Instructions

    • 1

      Hold the zinc against the outside of the transom -- the back of the boat -- below the waterline, and outline it with a china marker. Mark the location of the holes on the mounting bracket as well.

    • 2

      Strip any paint from the area inside the outline of the zinc by scraping the area with the edge of a putty knife blade. Soak a clean rag in acetone and wipe the space where you stripped the paint.

    • 3

      Drill holes through the hull at the locations marked for the mounting holes, using a drill.

    • 4

      Move inside the boat. Apply a thin coat of adhesive marine caulk to the area around each mounting hole and to the backs of the washers provided with the zinc.

    • 5

      Apply thread locker to the threads of each bolt. Insert the mounting bolts, provided with the zinc, through the side of the washer that has no caulking on it.

    • 6

      Thread the bolts through the mounting holes in the boat and into the zinc's mounting bracket, using your fingers. Tighten the bolts with an adjustable wrench only until the washer touches the caulk. The caulk must cure fully before you tighten the bolt; allow 24 hours for this process.

    • 7

      Tighten the bolts securely with the wrench.