The handbook should provide instructions for "leveling" (getting the correct angle) the fuselage by raising the tail and putting a bubble level on the tailcone with a ## by ## wedge. You can calculate the desired angle and use a bubble protractor instead, or one of the new electronic versions.

After weighing and measuring everything, you may hop in the cockpit and/or fill the ballast tanks to get a weighing at that configuration. You'll have to check the level again: even if the landing gear isn't sprung, the main wheel tire will deform more than the tail wheel tire (if you have one of those; life with a tail skid is mostly a hassle with this one exception!). Obviously this is at least a two-person job: one to strap into the cockpit and one to level the fuselage again by (almost certainly) lowering the tail slightly. Blocking the landing gear may prevent sagging on the springs but won't stop the tire from deforming slightly. No, I haven't done the math recently to figure out how much difference it makes but the last glider I did had a sprung landing gear so we just rechecked the fuselage angle anyway.

One thing you don't always think of: water sloshing around in the ballast tanks can shift the CG more than you think with slight changes in the angle of the fuselage. And if you have older flexible tanks, make sure they're slid down against the spar (hold the wing trailing edge down about 45 degrees during assembly and you'll hear the bags slide).

Or just don't worry about the ballast. The tanks will likely be forward of the likely CG anyway and should shift the CG in that direction. That assumes your CG is not already close to the forward limit, that is.

Chip Bearden