Morgan Ohlson wrote:
*** Jib size or Main/Foretriangle Ratio ***

If very theoretically 1 (equally large) must be the best. It lowers
(vertically) the CE to minimum and the shortest possible mast is needed.

1. What says that the main should be bigger?

2.Some boats have M/F-ratios of 4. That seems really stupid.

3. Is a self tacking jib a matter of importance when regarding the
M/F-ratio?

Ratio itself is just a number which in itself is not important.

Self tacking or not doesn't matter, really, except that self tacking
jibs must be smaller than the space in which they are flown, as the
jib club foot must pass between the headstay gooseneck and the mast.
It may also be required to pass in front of the foreward shrouds,
if other considerations permit using the club somewhat off the wind.

Interference with the pulpit bases while winged out is a
consideration. I prefer the longest possible club, so as to enable
flattening the jib in a constant way wrt the actual sheeting angle,
critical to good windward speed. All that depends on the geometery
and the system employed. The main advantage I find with a self
tending jib is really sheeting angle. Inboard sheeting angles permit
much better pointing, superior performance over a big baggy outboard
genny when there is enough apparrent wind. Off the wind I lower the
club and use regular outboard sheets, which are always attached even
when both are lazy, when using the "automatic" rig.

The actual ratio between sails isn't the key, here. It is a question
of balance overall and the relationship between sails in total verus
keel and rudder. A small jib may well improve weather helm over
going without.

Improve means reduce or increase, depending on your circumstances.

Terry K