How to Inspect and Replace Your Bow Eye and Transom Eyes

With the boat on the trailer, slack the winch strap. Look at the eye itself: rust, pitting, wear grooves from the hook, bends or cracks. Look at the gelcoat around the base: spider cracks, a gap, rust streaks or sealant squeezing out all suggest movement or a leak.

Grab the eye and push, pull and twist firmly. It should not move at all. Any wiggle, click or rotation means loose nuts, crushed core or a failing backing plate.

The bow eye nuts are usually inside the bow: in the anchor locker, a forward storage compartment, under a cabin berth or behind an access panel. Transom eye nuts are inside the transom, often in the bilge or behind the battery or livewell area. A flashlight, mirror and phone camera help in tight spots.

Look for rust on the nuts and washers, a missing or rotted backing plate, wet or dark laminate, soft spots, or old sealant that has failed. A U-bolt should have a plate or block across both legs. If the nuts are just bearing on bare fiberglass with small washers, plan to add a backing plate.

If nuts are just loose and everything else is sound, tighten them evenly until snug. Don't overtighten: on a cored transom or bow, cranking down crushes the core, which only makes the eye loose again. If a nut keeps turning without getting tight, stop; the core or plate is damaged.

• Keep: solid, no rust, no movement, no leaks.
• Rebed: the eye is in good shape but has moved or leaked; remove, clean, seal the hole and reinstall.
• Replace: pitted, worn, bent or cracked eye, rusted-through nuts, or a cheap plated eye. Use a stainless eye sized for your boat and trailer use.

Support the boat properly on the trailer (bunks or rollers taking the weight, and keep the boat from moving forward or back). Have a helper hold the outside while you remove the nuts inside. Tap the eye out from inside with a soft mallet if it's stuck in old sealant. Clean the holes and the hull surface with a plastic scraper.

Now look closely at the bolt legs. BoatUS's technical editor points to crevice corrosion, which hides exactly where the stainless passes through the hull and under the nut; a leg can look shiny outside and be pitted or cracked there. If in doubt, buy a new, stronger eye. It has to fit the flattened pad molded into the stem unless you carefully enlarge it, so measure the leg spacing before you order.

Probe the holes with a pick. If the laminate is solid fiberglass, clean and dry it. If you find core material (balsa, foam or wood) that's wet or soft, it needs drying and repair. BoatUS's backing-plate article says core in the area of a bolted fitting should be removed and replaced with something that won't crush, such as solid resin and fiberglass or a solid insert. For a small, sound hole, a common way to do this is to drill the hole oversize, fill it with thickened epoxy, let it cure, then redrill the bolt hole through the epoxy plug. Large wet areas are a pro job.

Use a plate that spreads the load across a much wider area than washers can: aluminum, stainless or epoxy-sealed marine plywood with tapered edges are common choices (BoatUS advises against soft polymer boards that slowly deform under bolt pressure). Bed it so it bears evenly on the rough inside surface rather than on a few high spots.

If the stem is thin where the eye mounts, BoatUS describes beefing it up from inside with several layers of woven fiberglass cloth and epoxy, flattening the area around the bolt holes while it's still soft so the plate sits flat, then redrilling. That is an advanced job; if you're not comfortable with fiberglass work, have a shop do it.

Aluminum boats: many small aluminum boats have a riveted bow eye bracket rather than a through-bolted U-bolt, and owners on iBoats report old cast eyes snapping at the ramp. If you switch to a stainless eye, keep stainless from touching the aluminum directly (non-metal gasket and backing, sealant on every fastener) so the hull doesn't corrode around it, and seal or replace any rivets you disturb (see aluminum rivet leaks).

Apply marine sealant to the eye's base and the bolt shanks so it fills the hole and forms a gasket outside. Push the eye through, fit the backing plate, washers and locknuts inside, and tighten evenly until sealant just squeezes out. Don't fully crush the sealant layer; follow the sealant maker's advice on final tightening after it cures.

Repeat the check on each transom eye. These often sit in a wet bilge area and corrode out of sight. They also take the shock loads of trailering and sometimes tow-sports harnesses, so give them the same backing plate and sealant care.

Inspect the winch strap and hook too. BoatUS advises replacing straps with frayed stitching, cuts, folds or heavy fading, and matching the strap rating to the winch and boat. Hook up, winch the boat snug against the bow stop, attach a separate safety chain or tie-down to the bow eye, and fit the stern straps to the transom eyes. Check for leaks the first time the boat goes in.