how to make the rounded foot
to make an exact calculation for the compleet sail you must calculate the
round foot first ,this means that the gore's of each panel which runs on to the foot has a different angle,in this way a round foot is created
for an average curve I mostly use the following rule,
place 1/3 of the length clew up on 2/5 of the length tack/clew work from the tack
(for drawings, go to the dutch version)
this means that the panel with this mark has the same gore aswel in the ruff as in the exact calculations and is the deepest point in the foot ,,,its easy for checking.
the panels that come's from the clew are used to make a smooth line to this x-panel and the panels that are going on to the tack are used for making a smooth line to this point.
lets say that we have a sail that has 9 panels in the foot the clewdown is 180 cm.
so all the gore's in the ruff calculation is 20cm. for each panel .
this means that if we cut all panels with a gore of 20 cm.,
we end up on the tack with a straight lined foot but we want a round foot
so lets try this
between the x-panel and the clew we have 5 panel's
we start with
panel 1 is cut off as good as 90 degrees so the gore is 0
panel 2 needs a little gore lets say -2 cm.
panel 3 needs a little more gore lets say -6 cm.
panel 4 needs a little more lets say -10 cm.
panel 5 we give -15cm gore see how we crawl to the gore of the x-panel
Xpanel6 -20cm. same gore as the ruff calculations
now we complete the foot with the 3 panels left in a nice curve to the tack
panel 7 but not to fast up lets say -30cm.
panel 8 now we need to go up so lets give this one -42cm.
panel 9 as last one we end up with a smooth line by the tack with -55cm.gore
in a sailtable it looks like this.
the gore's of the peak and luff are mostly the same as in the ruff calculation
so the changing numbers are from the fore and after side length of each panel.
the soma of al the new gore's in the round foot are equal to the length clew down
the yellow line's are fictional lines that runs from the gore then 90 degrees over to the atherside of the panel to give you the exact markingplace for making the closing line (the foot of the sail)which make's the triangular complete.
the line in the X panel this has same angle aswel in the ruff as in the exact calculations