There is not really any such thing as the "best fabric"; it depends entirely on the intended use of the cover, its location/environment and, to an extent, personal preference. Ideally the fabric protecting your boat should be breathable to keep down condensation and help prevent trapped moisture building up beneath the cover but there are many other considerations to take into account which will influence the final decision.
The guide below describes the properties of each of the main types of fabric used in boat covers and lists all the Pros & Cons for each so you can decide which is best for you and your boat. PVC-coated Polyester This is a fairly heavy fabric which tends to become stiff with age. It is generally coated with a PVC layer which can have a grained, matt or gloss textured finish on the top side and a smooth surface on the underside which is often silver/grey in colour. Some PVC’s have a canvas backing; these aren’t really suitable for boat covers although I have seen a fair few.
Pros 100% Waterproof Low maintenance: (they can easily be cleaned using soapy water, a hosepipe or even a power-wash. They don’t require any special treatment and will never need re-waterproofing.) Strong and robust Cons 100% Waterproof (Not breathable hence more condensation) Colour fades with time Fabric is heavy and more difficult to manage Stiffens over time
Acrylic Canvas This is a lighter-weight fabric made from woven solution-dyed acrylic yarn and looks much like a traditional canvas material. It will retain its colour for many years and remain flexible throughout its lifetime but does require a more care and routine maintenance including cleaning and re-proofing. It is available in a plain uncoated or PU coated versions. The uncoated is more breathable but less water resistant. It is typically used for making sprayhoods, sail covers and equipment bags/covers.
Pros Breathable Water resistant to 70cm (PU coated) or 35cm (Uncoated) UV Resistant guaranteed 5 years
Cons Not as hard wearing as most other fabrics Prone to Green on damp shaded areas Prone to Mould & Mildew in warm moist environment. Will need regular cleaning and occasional re-proofing to keep in top condition
Marine Polyester (Weathermax or Top Notch 9)
This is the lightest of all the fabrics and is specifically designed for large marine covers such as all-over boat covers but it is equally suitable for sprayhoods, canopies and enclosures of all types. It is an uncoated woven polyester fabric which performs amazingly well in a variety of marine environments.
Pros Highly Breathable Water resistant to 52 cm UV resistant guaranteed 5 years (except Red Shades) 2 x the Tensile Strength of Acrylic canvas 6 x the Abrasion Resistance of Acrylic canvas Dimensionally Stable - (Has negligible shrinkage or stretch) Cons More expensive than other fabrics. Being an uncoated fabric it can tend to let water pass when in contact with other surfaces e.g. over frames. This is generally outweighed by the fabric's breathability which allows moisture out of the cockpit area very swiftly. Prone to Green on damp shaded areas Prone to Mould & Mildew in warm moist environment. Will benefit from regular cleaning and occasional re-proofing to keep in top condition.
WHY DOES MY NEW COVER LEAK?
It is completely normal to see some water ingress on a new cover and we expect some water ingress through the seams. This can be exaggerated with persistent heavy rain on a new cover, especially if it doesn't get the opportunity to dry-out. This is part of the natural sealing process and seams will seal themselves after a few cycles of rainfall and drying.
The reason for this, is that the hole created by the needle in the sewing process is larger than the thread can fill. With weathering, the thread will swell to fill the hole, combined with the inherent impurities in the rain the stitch holes will become clogged and the seam will be waterproof. Please be assured that this initial leakage, whilst it may be alarming, will cease before too long. If you experience persistent problems please feel free to contact us.
HOW DO I CLEAN MY COVER?
It’s fair to say that PVC covers are the lowest maintenance option; they can easily be cleaned using soapy water, a hosepipe or even a power-wash. They don’t require any special treatment and will never need re-waterproofing. However, the life of a PVC cover can be greatly extended with careful cleaning and use of a good PVC protector which provides a barrier against atmospheric pollutants and UV.
Acrylic Canvas and Weathermax
To clean your canvas or Weathermax covers we recommend “Sprayhood & Tent Shampoo” from “ULTRAMAR”. (Don’t use detergents as they will damage the waterproof coating on the fabric). Apply the solution using the trigger-spray bottle paying attention to any persistent soiled areas. Allow to soak into the dirt for a while before rinsing with clean water. If you use a brush be careful not to use it on the vinyl windows as they will scratch.
DO NOT POWER-WASH Canvas or Polyester fabrics!
For more detailed information on cleaning please see our CANVAS CARE page.
HOW DO I WATERPROOF MY COVER?
Ensure that the fabric is clean and dry.
Avoid using a spray on windy days as you will lose much of the solution. Most waterproofing agents can also be applied by brush.
Work on one panel or area at a time being careful to avoid spray onto the windows.
Holding the spray nozzle about 12 inches from the fabric use slow sweeping strokes to apply the solution to the fabric evenly.