How to Replace Cleats, Eyes and Brackets on a Riveted Aluminum Boat

Look closely at the old fitting and the aluminum around it. White crust, bubbling paint and pits around the base or the fasteners mean the metals have been touching wet. Check underneath with a flashlight and mirror if you can reach. Wiggle the fitting: movement means loose fasteners or worn, elongated holes. Photograph everything before you take it apart.

If the old holes are round, clean and the right size for the new fitting, reuse them. If they're wallowed out, cracked, or in the wrong place for the new part, plan new holes at least a couple of fastener widths away and fill the old ones (step 11). Never put a new hole in a seam, a rivet line, or through a rib flange you can't see.

For bolts, hold the nut from below and turn it off. For rivets, center-punch the head and drill just through the head with a bit about the size of the rivet shank, then pop the rest out with a punch. Go slowly so the hole doesn't grow. Vacuum up every chip: steel drill debris or stainless chips left in the bilge rust and start corrosion spots of their own.

Scrape off old sealant and corrosion. Use a stainless or nylon brush kept only for aluminum, never a steel brush that leaves particles behind. Wipe with the cleaner your sealant maker recommends and let it dry completely. Touch up any bare aluminum that won't be under the fitting (see /guides/aluminum-hull-corrosion).

• Through-bolts with nuts are the strongest choice wherever you can reach the back: cleats, tow eyes, ski tow points, anything a rope or person pulls on. Use stainless bolts, isolating washers on both sides, and nylon-insert locknuts.
• Sealing (closed-end) blind rivets work where you can't reach the back, for light and medium loads such as rod holders, small brackets and trim. Practical Sailor found blind rivets grip thin metal very well, but open-end rivets have a hollow center that can let water through, so use sealing rivets anywhere water must be kept out.
• Rivet material for fittings: in Practical Sailor's fastener test, done on a sailboat mast rather than a hull, aluminum blind rivets were the weakest fasteners tried, and the testers saw them corrode more readily than stainless or Monel in salt air. That's a useful hint for fittings that carry load, but it isn't a hull test. Many owners use stainless or Monel blind rivets for brackets and holders, bedded in sealant or barrier paste, and save aluminum ones for light trim. Stainless rivets usually need a heavy-duty rivet tool.
• Hull seams are different: the rivets that hold the hull sheets together are usually solid aluminum rivets set with a hammer and a heavy steel "buck" held on the other side, not pop rivets. Cottage Life notes that standard pop rivets are useless below the waterline because of the hole through their center; a closed-end pop rivet is the one-sided option, and a small stainless machine screw and acorn nut set in flexible sealant can serve as a stopgap until a proper rivet goes in. Don't swap hull-seam rivets for fitting rivets; see /guides/aluminum-rivet-leaks.
• Machine screws into tapped aluminum can work in thicker extrusions, but threads in aluminum wear and corrode. Coarse threads resist stripping better in soft metal.
• Avoid sheet-metal and self-tapping screws for anything that carries load. Practical Sailor notes they're designed for very thin material and tend to snap or strip. See /guides/blind-fasteners-no-access for other options when the back is out of reach.

Anything that will be pulled hard needs load spread behind the skin. Practical Sailor recommends aluminum plate (about 1/8 to 1/4 inch) as backing for stainless or aluminum hardware: it's light, cheap, easy to cut with a jigsaw and, on an aluminum boat, the same metal as the hull. Non-metallic plates (marine-grade polymer board or fiberglass) avoid the metal question entirely. At a minimum, use large fender washers. Round the corners and drill the holes slightly oversize so bolts don't bind.

Hold the fitting in place and check that nuts and the backing plate fit behind, that nothing is in the way, and that ropes will lead fairly. Mark holes on masking tape. Center-punch each mark so the drill doesn't wander on smooth aluminum.

Drill the exact size the fastener or rivet maker specifies, with a sharp bit and steady pressure. Lightly deburr both sides so sealant and washers sit flat. Vacuum the chips right away, inside and out.

Put a nylon or plastic pad or washer under the base of the fitting, and isolating washers under bolt heads and nuts where stainless would otherwise touch aluminum. Coat bolt threads and shanks with a metal-free anti-seize or barrier paste; Sport Fishing suggests a lanolin-based thread lubricant to keep dissimilar metals from seizing and slow galvanic action. For rivets, dip each one in sealant so a little squeezes out when it's set.

Coat the base and each hole with marine bedding sealant. BoatUS (Don Casey) advises snugging fasteners just enough to squeeze sealant out all around, then waiting for the sealant to partly cure before the final tightening, turning the nuts rather than the bolts so you don't break the seal. Tighten evenly and stop when the fitting is firmly seated; don't crush the isolating washers or dimple the aluminum. Set rivets fully so the head pulls down tight and the stem breaks cleanly. Wipe off the squeeze-out.

Don't leave empty holes in an aluminum hull. Above the waterline, a small hole can be closed with a sealing rivet set in sealant, or with a flexible epoxy made for aluminum: Epoxyworks describes cleaning to shiny metal, then working thickened G/flex epoxy into gaps and around rivets. Anything below the waterline, cracked, or bigger than a rivet hole is a job for a welder or aluminum boat shop (see /guides/aluminum-rivet-leaks).

After the sealant has cured as long as the label says, give the fitting a firm, steady pull in the direction it will be loaded. On anything below the gunwale, fill the area with a hose or check the bilge after the first trip. Look again after a few outings for loosening, weeping or white powder. Log the hardware, fasteners and sealant used in BoatMend.