Sail and sale are homophones. I suspect incorrect usage usually occurs by accident or because the writer is more familiar with one word than the other.
Sail
- a sheet of material used to catch the wind and move a vessel over water
- a voyage or trip on a ship or boat; to voyage or travel on a ship or boat
- to navigate or control a ship
- to begin a voyage
- something that resembles a sail (in shape or function)
- to move along smoothly and rapidly or with confidence
Sale
- the exchange of goods or property for money
- an event or period during which goods are sold at reduced prices
My tip: a sale requires money; a sail requires wind.
Sources:
- Collins English Dictionary
- Oxford Dictionaries Online
Hannah McCall 
I guess if you are in the retail trade supplying yachting equipment you can get away with either.
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I feel like there’s a comedy sketch in that idea somewhere, but it would take a sharper wit than mine to make it work.
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Hadn’t thought of that……Agreed!
The late Ronnie Barker used to write scripts under an assumed name and used a great deal of word-play.
Someone of that calibre
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