I have long used custom tethers, because the bow of a cat is too wide for 6' to make sense. Making your own requires a good knowledge of sewing and strength. But small boat
sailors often need shorter tethers, and they would be happier not sewing there own.
How would you shorten a tether?
- Tie-off a loop. Messy, weakens it a bit, but almost certainly not enough to matter.
- Fold flat and sew. You could add a gusset and make it full strength, or you could assume the stitching would tear out above 500 pounds, providing shock absorption while getting longer.
- Double the tether around the jackline or hard point.