There is no "Standard Gain" for a 10 element Yagi.
The gain of a Yagi depends on
it's impedance, design bandwidth,
If the antenna is well built and well
designed, the gain
will be about 12 dBd.
Build as a cross Yagi, and a 90 deg phase harnass,
the antenna will have about 12 dBdc or 12 dB Circular Polarized gain.
Mounting a Cross
Yagi is also difficult.
A metal cross boom can detune the Yagi Elements.
It is best if the
antenna is end mounted.
But with VHF Cross Yagi's you can use a metal mast if
the antenna is
mounted X fashion, and the mounting boom
is vertical or horizontal.
Good luck Kent