Skylights for sailboats were originally designed from canvas. Early crafted canvases were made of hemp. Today, canvas is primarily made of cotton or linen and is designed from the most basic of three fundamental weave types -- being a plain weave or simple cross stitch.
Canvas is a heavyweight, durable fabric that is preferable for use in projects that require the utmost sturdiness -- such as skylight covers for sailboats, which necessitate a degree of immunity from the elements of a seafaring life. Canvas can be entirely waterproof or simply water resistant. It can be fireproof and also dyed, if desired. However treated, canvas fabric maintains its durability with exceptional breathability.
Modern-day marine fabrics were created with this ideal in mind and encompass literally hundreds of materials -- like acrylics, silicon-treated canvas, PVC-coated polyester vinyl and many, many more. These inventions make superlative skylight covers and protect the interior of a sailboat from steady sun exposure and extreme elements of weather.
Skylight covers are less of a necessity in this modern day, with the availability of tinted glass for skylight structure. These glasses admit ample natural light into the cabin while blocking out the harmful and deteriorating effects of the sun.
