Dear Scott - I would like to know how your extensive experience with high performance sailing ropes (sheets, halyards, braces, toppers, kickers etc) has led you to post a wild accusation which states that spectra 'does not like to be stretched' and 'can be more dangerous than $2 shop rope' whatever that is? 10mm spectra has a breaking load of 4500kgs - how on earth is that unsafe to tie something if you know how to use bowlines and hitches?? Could it be sour grapes? Remember that ratchet straps also assume the user knows how to attach them.
ps - spectra doesn't stretch - it's fibres elongate which is well within it's capabilities.
pss - might be a good idea to resist posting unless you have recent and relevant experience with the subject matter.
Hello again.
What brand of Spectra type rope do you use Oceans?
How do they indicate load rating on their Spectra rope?
What experience have you had on the matter?
What experience have I had on the matter?
Can you show me data supporting your idea where Spectra rope will tolerate a sudden loading such as a 500-1500kg engine suddenly moving in the event of an accident?
Can you tell us which exact knots you use to terminate and tension Spectra rope to hold a load?
What diameter of tie rail do you have on your trailer or ute?
Why are spectra type ropes not mentioned in the Load restraint Guide? Bungy cords are.
Why is it that in a brochure distributed by Barry ropes states categorically that "
Accidental dynamic loading Your ropes are
not designed to absorb the energy of an accidental dynamic loading. Care must taken to avoid this"
Page 10
http://www.barry.ca/publication/rt-inspection-dyneema-spectra-ropes-helicopter-products-jan-08.pdfI would have thought you'd have to allow for accidental dynamic loading when tying something onto the back of a truck or in a trailer. Why?? Accidents do happen. Accidents can even happen when they're least expected and can be caused by anyone/anything.
A breaking load (strain) of 4,500kg means near nothing if conditions to allow that tension are not met. What conditions allow a breaking strain of 4,500kg in Spectra rope? What conditions reduce this 4,500kg breaking strain?
Place a particular (and popular) hitch in a Spectra type rope and that breaking strain can be reduced by up to 65%. Your now down to a 1,575kg breaking strain.
If you want to mention spectra in marine vessels here is an interesting article about knots in Spectra type ropes on sailing vessels.
"Most purportedly cruiser-friendly Spectra rope is a double-braid hybrid with a Spectra core for strength and stretch-resistance and a polyester cover for chafe and sun protection and ease of handling. The problem is such hybrids still often feel quite stiff and a bit wire-like and the cover tends to slip over the core, making it necessary to sew the two together in areas of a line that are routinely clamped off in rope clutches. The complicated double-braid construction also makes the rope nearly impossible for most amateurs to splice.
This is a major bummer, because high-modulus rope like Spectra hates to have knots tied in it. Tie a knot in a high-mod line--bending it on to a sail's clew, for example--and you significantly degrade its load capacity".
http://www.wavetrain.net/boats-a-gear/163-paging-dr-rope-yale-phd-spectra-cordageThere is evidence to support that the use of Spectra type ropes do not safely restrain loads on vehicles especially in the event of an accident.
Where is the evidence to support the use of Spectra types ropes to safely restrain loads on vehicles?
'Cause I said so is not/will not be supporting evidence in a Court of Law (remembering a Judge will decide if your load was properly restrained in the event of an accident). References to support that you used an appropriate load restraining method will be needed.
The entire blame for any damages may well be placed upon yourself for using Spectra type ropes if it is proved you negated to take notice of warnings (The one mentioned by Barry is simply one out there on the information super highway).
Stating a breaking strain means nothing as evidence will be presented as to why the breaking strain had been reduced.
It seems to me that Spectra ropes are simply not designed for accidental dynamic loading. I would love it if I could be proven incorrect. Please prove me incorrect.
Would I personally use a Spectra type rope to hold a 500kg engine in a trailer or on the back of the ute? No way with the information given to me to date. Why? What happens if a cow or Kangaroo or pedestrian step out in front of me or a car t-bones me? What impact dynamic loading would be placed upon that Spectra type rope by that suddenly moving 500kg engine whilst continually thinking 'got to avoid accidental dynamic loading'?
Would I change my mind if supporting evidence was given to me? Maybe. But that would depend upon ease of knot tying, loadings, costings and a few other items.
Near every method of tying a load has it place. What do I use to hold my fishing rods on the roof of the car? Definitely not ropes or ratchet straps or chains. Bungy cords are my choice of load restraint in that instance.
Cheers Scott