Boat Cover

The [Condensed Version]

Your Boat Cover is only a season or two old but it is already leaking. We have all been there and have the solution. Read on to learn how to revitalize your canvas.

Getting drenched in a surprise shower out on the lake is no fun, especially when your Bimini top is supposed to keep you dry. We have all been there and experienced the two-season leaky-top itis. So, let’s get that boat cover ship-shape and properly waterproofed with the right Waterproofer for your boat cover or Bimini

Boat Cover Waterproofing

Boat Cover Waterproofing Article Image

Boat Cover Waterproofing

Let’s start with the materials. The classic canvas covers that your parents used are made with cotton. Consider, cotton strands act like the wooden planks on your deck, they swell and seal between the gaps when wet. So, this keeps water from dripping between the gaps and forces rain to flow off the boat cover. Understandably, cotton canvas has fallen out of favor because mildew can take hold and it tends to stain and discolor over time. Hence, why the boating industry adapted vinyl-coated polyester and acrylic woven fabric as its mainstays. These materials require less treatment and cleaning because their polymers are hydrophobic (waterproof) and so, will not absorb water.

Unfortunately, water can still pass through the gaps in any woven fabric but we will get to that in a moment. Every material has its drawbacks, vinyl-coated fabric will stay waterproof for the life of the material but it will not allow moisture to escape, causing moisture to build up. This inevitably leads to mold and mildew. But remember, vinyl is inexpensive and an effective short-term solution for Bimini tops but should not be used to enclose something like a sail or boat cover. In the past two decades, acrylic fabrics have become the material of choice of seafarers because of it’s breath-ability and strength.

Acrylic fabric is impregnated with compounds that resist UV light from sun exposure and will inherently stop mildew growth. Like most synthetic materials, it will not permanently stain and keeps it factory-fresh look for longer. Consequently, all of the big marine manufacturers have switched to acrylic and so it’s the primary pick for most people. 


Boat Cover Cleaning and Waterproofing Made Easy

Removing stains prior to waterproofing is recommended, use Starbrite’s Sail and Canvas Cleaner to prepare your boat canvas for boat canvas waterproofing. It is a
great economical option for boaters. If you are looking to protect your bimini top, use Starbrite’s Tower Gurar Marine Metal Cleaner and Protector. This product is safe to use on tower supports and canopy ribbing and ensures they are corrosion-free.

Wholesale Marine takes extra care in making sure that all your marine product needs are covered. We carry a full line of boat canvas waterproofing products along with anything else you may need for boat or boating needs.


Boat Canvas Waterproofing

Traditional cotton canvas is waterproof in the same manner that traditional wooden boats are waterproof. The cotton fibers — like the wooden planks — swell when they get wet. This seals the weave.

But because cotton canvas loves mildew and hates bird droppings, it is not used aboard pleasure boats much anymore. It has been replaced in most applications with either a vinyl-coated polyester or woven acrylic.

The vinyl-coated fabric is waterproof for the life of the fabric, but unlike traditional canvas, it doesn’t breathe. Unless it is well ventilated, condensation wets the underside of the fabric, eventually leading to mildew. Vinyl-coated fabrics are a good choice for Bimini tops, but unsuitable for enclosures such as sail covers or boat covers.

Acrylic canvas, like cotton canvas, is a tight-weave fabric. It is waterproof yet breathes; it stands up to ultraviolet radiation (sun exposure) better than any other fabric; it snubs mildew; it resists staining; it is colorfast and comes in every color imaginable; and it looks marvelous. Not surprisingly, acrylic canvas — Sunbrella being the best known — is the most popular marine fabric by a wide margin.

Acrylic canvas does have one negative characteristic, other than high cost. It gets its water repellency from a chemical treatment, not from swelling fibers, and eventually that treatment loses some of its effectiveness. Generally speaking, acrylic canvas in continuous use may start to leak after about three years. Scrubbing or the use of detergents to clean the canvas may hasten the failure of the coating. Fortunately, reproofing the canvas is easy.

How to Waterproof a Bimini Top or Sunbrella

Before you start, it’s important to understand that most waterproofing agents can damage your Gelcoat and put off dangerous fumes. These VOCs (thinning agents) are flammable and do irreparable damage to the environment. Additionally, the active waterproofing ingredient in these mass-market proofers is PTFE which will release PFOA and PFOS into the air and water over time. These chemicals cause cancer in human reproductive organs and are toxic to the environment. We strongly suggest you choose a waterproofing agent that lasts for years and is not toxic to your health. Hawk Tools is the only manufacturer with a fabric waterproofer that meets these requirements.


Sunbrella Recommends the Following Method :

  • Brush off loose dirt.
  • Spray on a cleaning solution of water and mild soap.
  • Use a soft bristle brush to clean.
  • Allow cleaning solution to soak into the fabric.
  • Rinse thoroughly until all soap residue is removed.
  • Air dry.

How to Waterproof a Boat Cover

How To:

  • Pick up a gallon of quality fabric weatherproofer. Get a paint brush and a medium size pot.
  • Thoroughly clean your boat cover with light detergent and water. Let it dry out in the sun.
  • Place the gallon of fabric weatherproofer in the pot and fill with 2 inches of water.
  • Simmer over heat until the weatherproofer is liquid and brush even coats onto the boat cover.
  • Make sure to test in an inconspicuous area to make sure you like the look.
  • After the fabric is completely saturated, scrape off any built up areas with a brush.
  • Let the weatherproofer cure in a warm dry place for 12 hours.

Chemicals and Your Boat Cover

After a couple of seasons, your pristine-looking boat cover or Bimini top will start leaking. Like with all woven fabric, water will start seeping through the gaps between the strands. Acrylic fibers cannot absorb water and so will not swell to fill the gaps. 


For this reason, all acrylic marine fabrics are sprayed with chemical waterproofing agents from the factory. When your top starts leaking, it’s the treatment that has worn out and needs re-application. So, a popular fix is chemical waterproofing sprays that can be purchased from marine supply stores. Just remember, every time you clean your boat cover, the chemical waterproofing agent is removed.


Are Aerosols Dangerous?


Acetone: The Delaware Health and Social Services Administration caution, breathing moderately to high amounts of acetone for a short amount of time can irritate your nose, throat, lungs, and eyes. It can also cause headaches, dizziness, confusion, a faster pulse, nausea, vomiting, effects on the blood, passing out and possible coma, and a shorter menstrual cycle in women.


Carbon Dioxide: Widely known as a primary cause of global warming, exposure to CO2 can produce a variety of health effects. These may include headaches, dizziness, restlessness, tingling or pins or needles feeling, difficulty breathing, sweating, tiredness, increased heart rate, elevated blood pressure, coma, asphyxia, and convulsions. Wisconsin Department of Health.


Isopropyl Alcohol: Repeated contact can cause a skin rash, itching, dryness, and redness. Inhaling Isopropyl Alcohol can irritate the nose and throat. Repeated high exposure can cause headaches, dizziness, confusion, loss of coordination, unconsciousness, and even death. Check out nj.gov for more info.


Alkylate Petroleum Naphtha: Extremely flammable. Irritating to eyes and respiratory system. Affects the central nervous system. Harmful or fatal if swallowed. Aspiration Hazard. Naptha causes brain damage. Read more about their study of automotive worker’s exposure to naphtha in this article by R F White and the NIH.


Fluorochemical Urethane: Fluorochemicals have known correlations with harmful health effects, such as cancer, increased cholesterol, and a weaker immune system in children. They can also decrease men’s and women’s ability to reproduce, and the chemicals can be transferred from mother to child during pregnancy and through breastmilk. For more, check out this article by the Technical University of Denmark.


Whats the Best Waterproofing Spray

If you enjoy living a long, healthy life and you want to keep the environment safe for future generations, the best waterproofing spray might be paint can shaped. Furthermore, a liquid eatherproofer that is made with natural beeswax and TYLOL from a reputable company like Hawk Tools.


Canvas Wax Ingredients:

  • Beeswax: Natural beeswax has been used for centuries by English and Norwegian seafarers and explorers to waterproof clothing and sails. That said, Paraffin became a less expensive substitute at the turn of the century.
  • Pine Tar: Native American peoples have been using pine rosin for centuries to waterproof canoes and clothing to great effect. It’s simply pine sap that is harvested by heating and rendering pine branches.
  • HT Proprietary Blend: Hawk Tools blends its own environmentally friendly waxes and oils for the best possible weatherproofing performance. Remember, never use a blend that contains toxic thinners or PFC’s!
  • TYLOL: A naturally derived compound that binds traditional fabric wax to modern synthetic fibers for the best of modern and classic weatherproofing technologies. 

Fabric Waterproofer Benefits

Fabric Weatherproofing is easily rubbed onto any synthetic or natural fiber cloth material for years of rainproof performance. For detailed instructions, check out this article about canvas wax. Unlike toxic aerosols that are inhaled and permanently poison the environment, fabric wax contains no harsh chemicals, instead, relying on nature’s finest materials for longer-lasting adhesion and abrasion resistance.

Seriously, a three hundred percent increase in abrasion resistance as stated in Max Moon’s article. Additionally, fabric weatherproofer penetrates deep into fibers, saturating the material and preventing any foreign fluids or stains from getting through. Conversely, aerosol spray only coats the surface of your fabric. So, you will have to re-apply frequently and expose your lungs and skin to even more toxic chemicals. Finally, if you like the classic look, smell, and performance of a better kind of fabric waterproofing, check out Hawk Tools Canvas Wax.

Marine Waterproofer Can

Ultra Durable

Boat Cover Waterproofer

Your Boat Cover deserves the most durable fabric weatherproofer available. Natural waxes and oils are reinforced with TYLOL, bonding the blend to synthetic and natural fibers for years of UV stable waterproofing performance.

Just warm the weatherproofer in a pot of simmering water and apply.

2 thoughts on “Boat Cover Waterproofing”

  1. Brenda Williams

    There is some duplicate content here from another article, you may want to clean some of it up before you post next time. Thanks for the great info though!

  2. Bart Amundson

    Will this waterproofer work on rubber or teak? Do you have any tutorials about how to waterproof sail materials?

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