One notion to explore would be that a knot with a 3 diameter turNip is better strength wise than a bowline that has 2 diameters in the turNip.
This holds interest to me but only if it has some scientific rigor in the test method and if it an prove certain hypothesis. If it does, then it would be of interest to include results in the 'Bowlines analysis' paper.
There have been many knot testers before you...and I would go so far as to say that in excess of 90% of cases - the results are near worthless (this comment might open me up to attack). The problem - in my view - is that the testers failed to establish robust test parameters - and then simply did knot A Vs knot B test and declared winners based on that short-sighted data.
I would support a test of the following parameters.
[ ] First test to establish baseline parameters - unkotted rope strength and then ABoK #1010 (Note: for unknotted rope test, you must fix each end with a 'tensionless hitch' containing at least 6 turns)
[ ] Identical knot specimens tied in both ends of the rope (so you have a survivor knot specimen to study and photograph)
[ ] Bearing point (BP) of eye to bearing point (BP) of eye length is always constant (eye of the knot to the opposite eye of the knot) - 500mm
[ ] Insert colored marker threads into the knots at strategic positions - photograph in pre-stressed state and then post failure state
[ ] Always use same rope type/model - don't change rope during testing
[ ] Always ensure the 'eye' of each knot is identical in size (same dimensions) - report size
pre and
post test
[ ] Always ensure that the same amount of tail is present in both knot specimens (eg 50mm tail) - report length
pre and
post test
[ ] Always ensure that both knots specimens at either end begin with identical dressing (ie cinched to same tension and form) - or as near to 'identical' as you can achieve
[ ] Take a photo of a knot specimen in its pre-loaded state - close up against a pure white background - and then indicate each of the dimensions - and these dimensions must always be identical for each test - eg eye size, tail length, eg for #1010, indicate tail length and eye dimensions.
[ ] I would suggest that you use a rope diameter of at least 8.0mm - but preferably larger diameter (although this will of course require much higher forces to cause failure). I am not in favour of using very thin cord as the rates of change in the dimensions of the nipping helix structure in thin cord is too small. I urge you to invest in thicker diameter cordage. Also, I urge you to to use kernmantel type cord - that is - cord used in climbing/abseiling/rescue applications. It will be more economical to purchase say 8.0mm cord in bulk on a spool (50m/100m).
[ ]
Please report if the knot specimen jams (or is jam resistant) - if it jams, please report the threshold at which jamming commences (ie at what tension force does jamming occur?)
Sequence:1. #1010 (500mm BP to BP) - single helix nipping structure (only 2 rope diameters inside captured inside single helix nipping structure)
2. #1010 (500mm BP to BP) - single helix nipping structure - with tail inserted back through nipping structure to create 3 rope diameters (see photo) - could be as per the photo below or perhaps Heinz Prohaska 'Double bight Bowline'
3. #1013 (500mm BP to BP) - double helix nipping structure
4. #1013 (500mm BP to BP) - double helix nipping structure - with Alan Lee's lock (tail inserted back through nipping structure to create 3 rope diameters)
In my view, this structured testing will help to identify what effect adding an extra rope diameter into the structure will have. Also, it will be interesting to compare a single helix nipping structure against a double helix nipping structure. This means that your testing will be a case of 'Single helix Bowline with 2 rope diameters Versus Double helix Bowline with 2 rope diameters and then move on to the Bowlines that have 3 rope diameters captured within the nipping helix structure (instead of simply Knot A versus Knot B type mentality).
Make sure you eat plenty of carrots before attempting to sew Dan Lehman's notorious little marker threads in to the knot specimens. Also, be sure to chant his name while doing the needle work
Note: Please take your photos against a
pure white background - and ensure no shadows are cast. If you do that, I will then be able to work with the images to bring them up to a high quality for you. But, if you don't shoot against a pure white background - there will be nothing I can do... It will also be helpful if you use a rope with a uniform color - for example, I like to work with Blue as it is easy for me to manipulate the saturation and tone curve because obviously blue is one of the primary RGB colors.
After obtaining these data points, you could then try testing different nipping structures - such as those based on a 'crossing hitch' (ie munter hitch). Eg Crossing hitch nipping structure versus standard #1010 single helix nipping structure.
If you can capture all of this data, it will be of immense value
Mark G
Edited: with additional important test parameters (eg tail length identical on both knot specimens - as this will provide insight into how this length changes as load increases to failure... and the eye of each knot must be of the same dimensions)
