Gogarty wrote:
... I did most of my research at the Library of Congress
and had access to all the original documents.

I doubt those sails could have been very effective at all. Puts me in mind of
vestigial organs or limbs that once had a function but no longer do and
nobody can figure out why they are still there except they always have been.
I measn look at the design of your average 1920s megayacht with long bowsprit
and clipper bow and raked masts that might carry sails but never did.


My guess, for what it's worth:
with no sails, Titanic might have made 3 points off downwind to either
side with no adverse run of the sea.
With both sails set, you might notch it up to 4 points off the downwind,
and a shade faster....

Brian W