Gross stupidity mixed with a little bad luck.

I'm kicking myself today. Another blue day with a late start. The start gate was just a few km from the solitary cu in the sky, which were at about 7000ft. I had a late launch so spent a lot of time struggling at release height before finally connecting with the cu and then having to burn off the altitude to get below 5000ft start. The main gaggle had already left by this stage and the obvious move was to head straight back to the cu and climb before heading out on course. By the time I got to it, it was dying and got me only to about 5500 ft before dropping to a kt or so. I headed out on track, got some positive air but noting usable until deep into the first area. A weak climb took me to about 4500 and I turned and came along the ridge toward the north end of the second sector but hit nothing. Finally turning out into the valley I worked over a tractor in a brown field but very slowly lost out height and eventually landed. What I should have done - well put up with the weak climb back to base, and then go for minimum distance? But we had no idea the lift on course was going to be so poor. Well tomorrow is another day. At least the farmer let me borrow his quad!