Kurt.. your mechanic that does the weighing will know this.
But an "incidence board" is a "wedge" that would rise 24 inches (or
centimeters) over a distance of 600 of the same inches or centimeters.
It is a "set slope", the back of the grob fuselage just in front of the
curve where the vertical fin starts is not "level", you could not place a
level there to level the fuselage for weighing. Add this incidence board,
place the level on the board, make the bubble level and take the main and
tail wheel weights. Compute the empty CG per the POH.

If thinking "inches", 600:24 = 300:12 = 150:6
divide by 10, a 15in long board placed on the fuselage as directed in the
weighing instructions would rise 6 tenths (0.6) of an inch for the distance.
BT

wrote in message
ups.com...
We are going to have our Grob 103 weighed next week. In the flight
manual it says "Level means 600:24 incidence board" set up
horizontial on the top of the rear fuselage. I plead
ignorance....what is a 600:24 incidence board?

Thanks

Kurt