How to Replace or Re-Cover a Bimini Top

Put the top up in its normal position and take photos from both sides, the front, the back and from underneath. Get close-ups of how straps attach, where the snaps are, and how the boot fits. These pictures save a lot of head-scratching later.

With the top up, check:

• Tubes: bends, cracks, dents, or heavy pitting at the joints.
• Deck hinges and jaw slides: cracked plastic, worn or bent pins, stripped screws, or loose mounts in the deck.
• Eye ends and pins: missing lanyards and worn holes.
• Straps and buckles: faded, stiff or frayed webbing. Straps are cheap and usually worth replacing with the canvas.

If you're replacing the frame too, BoatUS's buying notes: anodized aluminum is usually fine and cheaper on fresh water, while stainless is stronger and worth the extra cost on salt water and faster boats. Drawn tubing is denser and stronger than extruded. Stainless fittings outlast coated brass ones, which tend to corrode, peel and break.

Write down anything that needs replacing and match the parts to your tubing size. If deck mounts are loose or the deck feels soft around them, read the tower-hardware-check guide before you put load back on them.

Measure straight across the boat between the deck hinges where the bows attach to the gunwales. Measure where the frame actually mounts, not the width of the old canvas: old fabric stretches and shrinks, and canvas is cut with some overhang. BoatUS notes that bimini bows can flex a few inches in or out at the gunwale, which is why stock tops cover a range of widths. Order for the width your hinges are actually at.

• Length: with the top up, measure fore and aft across the top, front bow to back bow. BoatUS notes stock tops commonly run about 4 to 8 feet long, with 6 feet being a common size.
• Height: measure from the deck hinge straight up to the top of the frame when it's deployed. Pick a height that lets the tallest regular helmsman stand without ducking, and check it still clears any windshield, T-top or radar arch when folded.
• Shape: note the number of bows and whether the top is meant to be flat or rounded down at the sides.

Boating Magazine suggests at least one bow for every two feet of top length so the fabric doesn't sag and pool water.

• Solution-dyed acrylic (Sunbrella and similar): the most common bimini fabric. It holds its color best, breathes, and resists stretching and shrinking. It's water-resistant rather than fully waterproof and wears faster where it rubs the frame.
• Vinyl-coated polyester: waterproof and tougher where it bears on the frame, easy to clean, but less colorfast. It doesn't breathe.
• Vinyl-coated acrylic: waterproof with an acrylic face, but noticeably heavier.
• Plain polyester: found on many low-cost stock tops. It's cheaper but generally fades and weakens sooner in strong sun; check the maker's UV rating and warranty.

Boating Magazine warns that red, orange, burgundy and yellow fade fastest in UV. Matching fabric piping lasts longer than white vinyl trim.

• Stock replacement canvas: cheapest; works when your frame is a common size and brand. Read the fit notes carefully.
• Complete kit: new frame, canvas, straps and hardware. Good when the frame is tired.
• Custom canvas shop: best fit, your choice of fabric and thread, and they can add reinforcement where the fabric rubs. Bring your photos and measurements, or ask them to template the boat.

Ask any maker what thread they use (UV-resistant thread outlasts standard polyester thread), whether chafe patches are included at the bows, and what the warranty covers. BoatUS points out that ordinary polyester thread often needs restitching before the fabric wears out; premium PTFE thread costs more but is meant to last as long as the fabric. If you'll add curtains later, ask for plastic zippers covered by a fabric flap, since metal zippers corrode and bare plastic ones break down in UV.

Fold the top down, put the boot on, and pull the hinge pins or loosen the deck hinges as your frame allows. With a helper, lift the whole frame off and carry it to a clean tarp or grass. Bag every pin, bolt and washer as it comes off.

Remove the boot, open the frame and lay it top-down with the legs pointing up. Unstrap the webbing from the frame and remove the bolts at the jaw slides on each side (keep the hardware). Inside each bow pocket there's usually a center snap or tab holding the canvas in place; unclip it. Then slide each bow out of its pocket, watching that fittings don't snag and tear the fabric.

Lay the new canvas out the same way round as the old one. Slide the bow with the most fittings through its pocket first, guiding the fittings carefully, and fasten its center snap. Repeat with the front bow (watch for strap cutouts) and then the middle bow or bows. Rebuild one side of the frame at a time: reconnect the bows, refit the jaw slide bolts and snug them, then do the other side. Don't overtighten into plastic fittings.

Reattach the rear supports and feed the front straps through their cutouts and around the bows. Put the frame back on the deck hinges, deploy the top, and adjust the straps until the canvas is evenly tight with no wrinkles or water-pooling dips. BoatUS notes straps fold down easily but are less rigid than fixed support poles, which matters if you plan to add side curtains later.

Look along the top from the side: the fabric should be smooth and taut, the frame square to the boat, and the top shouldn't rub the windshield or antennas. Pour a bucket of water on the top to check that it sheds water instead of pooling. Fold the top down and up twice to make sure nothing binds.

Lubricate zippers and snaps, fit the boot, and log the install date in BoatMend. New acrylic canvas can feel tight at first; avoid forcing snaps that don't quite reach on a cold day (see the canvas-snap-repair guide). Wash it with mild soap and fresh water as the canvas-vinyl-care guide describes.

Care that makes the new top last (from BoatUS and Sailrite's Sunbrella cleaning guide):

• Brush off bird droppings and bug splatter as soon as you see them; left on, they stain and weaken fabric and thread.
• Rinse the top with plain water about once a month in season. Never use a pressure washer, and let it air dry.
• After a deep cleaning, the water-repellent finish may need renewing with a fabric reproofer. Two thin coats work better than one heavy one, and many products shouldn't cure in direct sun, so check the label.
• Sunbrella's own marine canvas page says monthly rinsing means most tops only need a thorough cleaning every two to three years. For mildew or stubborn stains it gives a diluted bleach-and-mild-soap mix for spot cleaning, then a very thorough rinse; spray only (don't scrub) the coated underside of coated versions. It also cautions that bleach can discolor non-Sunbrella fabrics nearby, can harm the water around the boat (so it doesn't advise bleach where runoff reaches the water; take the top ashore), and, with age, can weaken the thread and other non-Sunbrella parts.
• Take the top down, clean, dry and store it for winter layup. BoatUS warns a bimini is not a winter cover; snow load and storm winds can wreck it in one season.