It appears to be at least partially based in historical fact. Most of the historical images of Viking ships show red & white vertical stripes. Also, per some cursory research on Google ("why do Viking longboats have red and white stripes"), it appears that tanning the wool or linen would make sails last longer. There are also some theories, based on modern use, that colour is good because it can be painful to stare at undyed sails all day.

It occurred to me that arguably William of Normandy's ships in 1066 were viking. They are shown as stripey, but not necessarily red and white:

(from http://www.bayeuxtapestry.org.uk/)

I wonder when the convention of red and white was established.

It's actually red and yellow, indicates the track is wet or oily (in this case, wet):

https://en.wikipedia.org/wiki/Racing_flags#Red_and_yellow_striped_flag

They should be a chequered pattern, it's an artifact of how they were constructed. Fragments have been found which were dyed red, however.
(links removed as it got spamtrapped)

Indeed. Their looms tend to limit the cloth to about 3 feet wide. One theory is that the chequer pattern is because they wove the narrow strips together on the diagonal to make up the sail.