I don't know if it still operates, but there used to be a sailboat which took tourists on a cruise of Florida Bay, in Everglades National Park. It was beautiful to see, with its dark red sails against the turquoise water.

Recently I read up on 'red' sails. There are reddish-brown chemicals, which, applied to white sails, made them last longer. A boat with red sails was apt to be owned by the people who were operating it, because they cared more about it and took better care of it.

(I needed to know because I had bought a coloring book about sailboats.)

Perhaps nowadays, when sails are made of strong synthetics, sails do not need to be treated.