Why Dyneema instead of wire rope and steel fittings? – The advantages of Dyneema rope
Rope is lighter than stainless steel or wire and it also has a higher breaking load in some cases. This is especially true for racing and regatta vessels, which become noticeably faster due to the significant amount of weight saved by using rope-based rigging on-board. A basic maritime rule is that each additional kilogram of rigging must be compensated by about seven kilograms of extra ballast, in order to keep the vessel sturdy.
The polyethylene used for the production of Dyneema has extremely long molecular chains, which ensure a very high tensile strength of the material. Dyneema rigging can be up to 5 times the tensile strength of regular polyester rigging and it’s just as strong as steel when it's at the same thickness. Dyneema has the lowest elongation at break in comparison to all other synthetic fibers. Moreover, Dyneema rigging is fairly easy to splice and rig. Another advantage of Dyneema rigging on board of a yacht, is their great degree of buoyancy, seeing as they are lighter than water, and their UV resistance. The only significant disadvantage of Dyneema rigging is their permanent elongation under high stress, which is also called "creeping".
When was Dyneema rope invented?
In the 80’s, the firm DSM invented Dyneema synthetic fibers, which provide extremely strong tensile strength and a very low degree of stretch. This was done by using "Ultra-High Molecular Weight Polyethylene (UHMWPE)", which is basically material made out of extremely high molar mass and stretched molecular chains.
Why less stretch in running rigging results in greater performance
The special secret of Dyneema is its extremely long molecular chains, which carry load better on their polymer structure. Dyneema rigging can be up to 5 times the tensile strength of regular polyester rigging and it’s just as strong as steel when its at the same thickness. Dyneema has the lowest elongation at break in comparison to all other synthetic fibers. Moreover, Dyneema rigging is fairly easy to splice and rig. Another advantage of Dyneema rigging on board of a yacht, is their great degree of buoyancy, seeing as they are lighter than water. The only significant disadvantage of Dyneema rigging is their permanent elongation under high stress, which is also called "creeping".
What is the role of the core and sheath with Dyneema rope?
Since the invention of Dyneema high-performance rigging, the Dutch company DSM has optimized and changed their fibers several times. The first fiber type was designated as SK 60. The next types were then called: SK 75, 76, 78, 90, 95 and 99. SVB offers Dyneema rigging from the Gleistein brand, based in Bremen, Germany. For use on yachts, braided rigging is almost exclusively used, usually with a core-sheath braid, wherein the core takes the burden of the tensile forces and the outer sheath protects the core. We offer both rigging made out of pure, coated Dyneema fiber, such as Gleistein´s DYNA ONE and rigging with a Dyneema core and polyester sheath.
The Dyneema core reduces stretching on sheets and the sheathing around the Dyneema core ensures that the rigging is held secure on winches, cleats and stoppers. This way, the sheath doesn’t have to bear the load. The specific type of design and braiding is of the most importance in assuring a quality core. Normally, a twelve- or sixteen-fold braid is used for the core. In the case of twelve-fold braiding, individual braids tend to move in the direction of the load, whereas in the case of sixteen-fold braiding - the individual braids entwine less and are contained to a higher degree, considering the given length and thickness of the core fiber material, which reduces the stretching of sheets.
We supply ropes made of pure, coated Dyneema fibre as well as ropes with Dyneema core and polyester sheathing.
Why you should splice Dyneema rope and never knot it
Dyneema rigging should be spliced, not knotted, because knotting Dyneema fiber decreases its breaking load by about 50%, therefore requiring larger dimensions. A properly executed splice ensures that the cable provides the greatest amount of strength with the lowest amount of breaking load loss. Thus, an extra sheath between the core and outer sheath can by applied by our professional splicers in some places, which need to be thicker (for example, parts lying on winches and stoppers). Generally Dyneema rigging can be spliced fairly easily, whether it’s: spliced eye, thimble slice or rope connection . Here is a comparison chart of the strength of Dyneema splices compared to knots with ropes 16mm in diameter.
Tensile strength of spliced vs. burled Dyneema rope
|Ø mm||Breaking force on splices||Max. loss of breaking force||Breaking force on bowlines [daN]||Breaking force on figure eight knots [daN]|
What Dyneema rope is right for high-performance and regatta sailors?
Regatta sailing is a high-performance sport, in which sailors require great stamina, experience and performance. On top of teamwork, the best materials and rigging are also essential. As a regatta sailor, you naturally need running rigging with minimal stretch and the lowest possible top weight. A low degree of stretching is ensured by Dyneema’s fiber core. The outer sheath should also provide the best possible grip in the fittings as well. In order to save even more weight, we offer our regatta sailors with the TAPERTWIN, by Gleistein. This type of rigging is constructed out of pure Dyneema 12x braid, with a special coating and without a sheath. DYNA ONE provides the strength and breaking load of a wire rope at one-eighth the size. Especially when used as a control, trim or steering line, it comes as a great advantage aboard racing and regatta yachts. By not having a sheath, not only is a lot of unnecessary weight spared, but it also runs smoother through blocks and diversions as well.
Which Dyneema rope for cruising and ocean-going sailors?
If you’re a cruising or offshore sailor and you sail for several days or even weeks at a time in high winds and rough seas, the demands on your running rigging increase. Your halyards and sheets must be able to bear extreme loads, due to the fact that your washers, stoppers and winches may cause abrasion and the long-term expansion of your running rigging may also cause increased wear. Here we advise you to use halyards and sheets with pure Dyneema core with 12-braids, such as CRUISE XP, developed by Gleistein. This type of rigging guarantees sufficient tension on your halyards over a longer period of time and they are available in different colors and levels of thicknesses, which also offer the end-user with an optimal price to performance ratio as well.
Which Dyneema rope for weekend & recreational sailors?
Finding out which type of Dyneema rigging suits you and your yacht the best is decided by your sailing habits. For weekend and recreational sailors, the classic „CUP“ or "HARKON" or rigging solutions without Dyneema fiber can be used, since this type of sailing doesn’t require expensive or high-performance rigging.
How to find the perfect Dyneema rope for your boat
|Rigging application||Cruise XP||MegaTwin Dyneema||Dyna One||Dyna Lite|
|Spinnaker boom downhaul|
|Gennaker tack controller|
|Jib furler line|
|Main sheet traveler|