Multifunctional

• Canvas has been in use for centuries.Jupiterimages/Goodshoot/Getty Images
  
  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.
  
  

Synthetic Alternatives

• 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.
  
  

Ability to Block

• The sun is only one of many elements that can be destructive to a sailboat's structure.Jupiterimages/Photos.com/Getty Images
  
  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.