So these are the nitty gritty details. Skip this if all you are interested in are the results later:
Equipment used:
Two speed manual Lewmar 54 self tailing sheet winch
Old double braided polyester 16 mm and 10 mm (sailors very rarely use new line, so this is useful information for us).
Calipers
Camera
Measurements taken:
18 were taken for each test:
- To judge the amount of stretch in the thinner line (and therefore get a rough idea of the load applied) three sets each of the length of the line between two points was measured before and under the final load applied
- Three sets each of the length of the tail of each line before and after.
Method:
- A loop was tied in the middle of the thinner line so that I could throw it around the drum of a nearby winch. Initially a midline bowline was used, but that seemed to need care so that it did not elongate too much under load, so I switched to an Alpine Butterfly loop (grrrrrrr, more about that later)
- Bends were tied and dressed and photographed
- The lines were transferred to the winch with 4 turns of the thicker line around the winch (within half a metre of the location they were tied), but the lines left slack and the bend tightened as carefully and as much as I physically could
- I took measurements as described above
- Load was slowly applied by turning the handle on the higher gear. I continued to turn the handle until no further movement was possible (two hands)
- the length between the chosen two points on the standing line was measured 3 times again, the load removed and the length of the tails measured.
I plan to do at least 3 lots of measurements, 5 if enthusiasm persists.
If anyone can see any improvements I can make in technique, please let me know. Too late to change for this trial, but if I do any more it will help.