How to Clean and Care for a Boat Windshield (Acrylic, Polycarbonate or Glass)

Hose the windshield gently, top to bottom, inside and out, to float away salt crystals, sand and dust. Never wipe a dry, dusty windshield. Salt is hard enough to scratch plastic.

Use a bucket of mild soapy water and a clean, soft microfiber or cotton cloth. Wipe lightly in straight lines, not circles. Rinse the cloth often and swap it when it picks up grit. Avoid paper towels, scrub pads, stiff brushes and squeegees on plastic. Practical Sailor's cleaner test adds that sponges trap grit too; wash the cloth (or throw it out) after each session so it can't scratch the next time.

Rinse off all soap, then blot or wipe dry with a fresh, clean cloth. Drying stops water spots, especially in hard water areas.

• Acrylic and polycarbonate: use a cleaner and polish made for clear plastic. Practical Sailor warns that ammonia, alcohol and solvents damage acrylic, and the Canadian Conservation Institute warns that some solvents cause crazing (a web of fine cracks). That rules out most household glass cleaners, acetone and fuel. A plastic polish also fills fine pores so dirt sticks less.
• Glass: an ammonia-free glass cleaner is fine. Keep it off nearby plastic trim and rubber seals.
• Hard-water spots on glass: BoatUS editors spray a mix of equal parts white vinegar and water, wait a few minutes and wipe it off. To prevent new spots, wash in the shade and dry right away with a clean chamois or microfiber before droplets dry. Test on a corner first and keep it off plastic panels unless the panel maker says vinegar is safe.

Light haze and fine scratches on acrylic can often be polished out with a plastic scratch-remover system used from coarsest to finest. In Boating Magazine's tests, multi-step kits removed light scratches; heavier scratches needed an aggressive sanding kit that the testers called a last resort before replacement. Test any product on a corner first, work at a right angle to the scratches, and check the result in full sun, because uneven polishing creates distortion. Coated polycarbonate: Boating Magazine notes that some restoration products can damage or destroy the coating. Use only what the windshield maker approves, or have a pro look at it.

Crazing looks like a network of tiny cracks, often near screw holes, edges or where a solvent touched the plastic. It doesn't polish out. Find and stop the cause (a harsh cleaner, an incompatible sealant, or a frame screw that's too tight), then plan to replace the panel if it spreads into your line of sight.

A crack in acrylic tends to keep running with vibration and temperature changes. As a temporary fix until replacement, a pro (or a careful owner) can stop-drill it: drill a small, clean hole just beyond the visible tip of the crack using a bit suited to plastic, at low speed, with the panel supported from behind. The round hole spreads the stress so the crack stops. Mark the tip with tape and watch it; if it keeps growing, replace the panel. A cracked glass windshield can't be repaired this way: replace it.

Close the walk-through door. Have a helper sit inside with a flashlight while you run a gentle hose stream along one short section of the frame at a time, starting low and working up. Mark each drip with tape. Look at whether water is coming between the plastic or glass and its rubber seal, or between the frame and the deck. Then inspect that spot for cracked, shrunken or missing seal and loose screws.

Tighten loose frame screws snugly but not hard (overtightening cracks plastic). Replace hardened or torn rubber seals with parts for your windshield. Where the frame meets the deck, remove the old sealant completely and re-bed with a marine sealant whose label says it is safe for acrylic or polycarbonate; some sealants and their solvents can craze plastic. Big leaks or a frame that has to come off are worth a pro, because the panels can crack while being removed.

Open and close the walk-through panel a few times. Rinse salt out of the hinges and latch, check that hinge and latch screws are tight, and lubricate them with a marine lubricant that is safe on plastics (keep it off the clear panel). Replace a flattened or torn door seal. If the door suddenly won't latch or rubs the frame, look for a loose frame screw or a bent hinge first. A door that no longer lines up for no obvious reason can be a sign of flexing in the dash or deck, which a pro should check.

Lift the blade and look for cracked, hardened or chewed-up rubber. Replace it when it streaks or chatters. Never run a wiper on a dry or salty plastic windshield: wet it with fresh water first, or the blade drags grit across the surface. Check that the arm presses evenly, the mounting nut is tight, and the boot or seal where the shaft goes through the windshield or dash isn't cracked (that's a common leak).

Clean and dry the windshield before covering the boat. Pad windshield corners and edges under the cover; the BoatUS Foundation found that covers rub and wear at sharp points as they settle, and specifically says not to forget the windscreen edges. Make sure no cover support pole presses on the windshield or its frame.