Exactly, Chris laid it out
May I add, that it would not only require greater skill and attention if too short - it would definitely NOT be possible to ride (fast/foiling) at all, when there is chop waves.
Out today in about 10 knots (perfect power in a 10m2), and there was 1 meter chop waves.
Works great with a 100cm mast (like my Zeeko is), but much shorter would definitely not work in our waters, and will give brutal crashes and board touching the wave tops so slows down OR crashes
Furthermore, when you go upwind powered, the foil is tilted a lot - so the wing is not very deep, thus even worse when big chop.
BUT, the most amazing feel when hydrofoiling, is IMO that you wont feel the chop waves at all, you just blast through feeling nothing, and everything is totally silent - AMAZING
The only situation where you can feel that there is "mess" under the surface, is when you f.ex cross a speedboats wake.
These waves are so messy, that although you can easily ride fluid through - you CAN feel this in your feet - something that "tickles" the foil wing so to speak
Experienced it again today, a couple of hours ago.
In other spots the water is much more "flat", especially if only 10 knots which is quite well powered for a foil, thus a shorter mast can easily be used.
So Chris is right, the mast seems to range from 80 to 100cm on those I know of, and seems to fit most conditions well, as average.
Actually, a much longer mast could be really fun, just to try to soar/drift/hover even higher above the water - a GREAT feeling
But not as practical and most likely slower because of handling and stiffness issues...
PS: That is definitely not dumb questions balugh.
PPS: Before you say I am full of bull, saying that you can ride 1m chop waves with only a 1m mast, let me explain - when the (max) waves are 1m, they are a bit "wider" and you can easily adjust yourself, so you avoid ventilation (air sucks down and you most often crash if the wing breaks free from the water), and smaller but also much more narrow chop is just "invisible", and good, as you would not be able to adjust pitch for these....