Bloody engineers

, cant leave anything alone. Ill give you some marks for the maths though, quite correct - even the drag factor, good lad. Now, without getting into a 'downwind for dummies' (if you've got three days of you life spare, read this thread
http://www.kiteforum.com/phpbb/viewtopic.php?t=2329828&highlight=), you forgot the following.
If were talking about thinner lines, then we need to look at the difference in drag, not the total - lets make some simple assumptions - thick i.e. stiffer lines are 4mm, thin lines are 2-3mm? Worst case, the variation is 2mm, so the addtional drag from thicker lines equates to 20N or 2kgs.
Also, remember that this does not have a direct effect on the kite end of the lines, but is distributed along the entire length of the lines, plus the fact the while your moving, the wind is not hitting the lines at a perpendicular angle. And thats not even going into apparent wind.
Conincedently, I sneezed while I was on the scales this morning, and was exactly 2 kilos lighter than yesterday. You'll have to shout me a beer some time and I'll impart some other pearls of wisdom. Honestly, when I know Im right, I'm such an arse.
Now back to the original topic - if your setting up using 4 lines and that includes bowmosexuals, attach the 2 front lines before you unwind your lines, then once the bar is out and the lines are laid flat, put some tension on the lines. Walk the backies out and you're away. This is by far the quickest and error free method.