FYI the original model failed in Norway last year - basically the tenons on the cross bar were too small and weak to take the stress. i have made another on the same lines but i made the cross bar about 15mm deeper and the tenons and holes correspondingly larger.
I tried it out at swyns a few weeks ago and it seemed much better.
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I also have my doubts about the use of paracord as the tensioner as the stretch on the nylon may have contributed to the failure by allowing too much play in use so i am experimenting with thick 'post office parcel string' to see if this feels better.