"derbyrm" ) writes:
By coincidence, I just finished re-reading the Yachting Monthly article on
"The Fastest Rig" (July 1984). According to their tests using identical
hulls and rigs with identical sail area, the sprit rig was the fastest on
all points of sail. To windward, it was 30% faster than the
Bermudian/Marconi. Only the lateen was poorer than the Bermuda rig which
survives (dominates) because of the racing rules. (And the lateen was as
good in light airs.)

Wind tunnel tests in the UK showed the lateen rig to be the least
efficient. It's efficiency depends a lot on the angle of the top spar.
Almost verticle is best. The tests showed the crab claw to be the most
powerful sail (actually works like a kite not an aerofoil) but it's
difficlut to manage in narrow waters and shifting winds. The bermuda sloop
rig (high aspect marconi version) was the most efficient overall due to
better sailing to windward. IFRC the sprit and gunter were about the same.
The experiments were done by a famous Poish Finn (an oxymoron?) sailor who
has gone on to study sails but I can't remember his name just now. He has
written research papers and popular books on sails.

One thing that greatly affects a sail's efficiency is the leading edge. A
mast sleeve helps because it minimizes turbulance at the leading edge.

A lot of times sails were chosen for other reasons, eg ease of handling
or cost.

BTW it's called "marconi" after early radio antenna towers built by the
inventor Marconi. The high aspect bermuda rigs had to be stayed like his
radio towers.