Pretty good video from EAA regarding Weight and Balance.
http://www.eaavideo.org/video.aspx?v=666144934001It reminds us of several very important aspects of weighing our airplanes. Leveling, finding the datum, and properly draining the aircraft of fuel leaving the unusable few behind.
I've seen on a few occasions lately, one or more of the following; people not properly leveling their airplanes, leaving fuel in and subtracting the assumed amount of fuel weight (simply guessing at what was in the tank) and not properly locating the datum.
Another good reminder is that with our airplanes we have a pretty good variation of where the wheels (both main and tail) are in relation to datum depending on S-18 (T-18W)/T-18, extended gear/short gear, trusty tail-wheel/leaf spring etc. So grabbing someone elses spreadsheet and plugging the main/tail gear weights in is not the way to go. You need to measure the location of the gear on your specific aircraft, doing that and altering a spreadsheet from someone else is fine, just don't forget that all our airplanes are different.
Safety tip for the evening [;)]