I thought something seemed off with the diagram too, and also believed your
last paragraph to be true. I can see the perpendicular force in the first
figure, but when close hauled, as in fig 2, especially considering the wind
on the structure, I'm not sure why that vector isn't running "slightly" more
toward the stern?
Scout

"Donal" wrote in message
...

"Scout" wrote in message
...
Is sideways force always exactly perpendicular to the boat's centerline,
as
shown by the vectors in Sleight's Manual (link below)? Can the camber of
the
sail be forced to shift that force slightly forward?
http://scout235.tripod.com/Sleight_p_31.jpg

I think that whoever did those diagrams didn't understand very much about
physics.

What does "sideways force" actually mean? If you think about it, sideways
force must always be perpindicular to the centreline.

In reality, a force is exerted upon a boat in line with the wind. The
sails
and keel combine to produce a forward motion that may not be directly
downwind.


Regards


Donal
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