Krypton-D Double Braid rope consists of a Polyester sleeve covering a Dyneema (same fiber as Spectra - see below) core to form a very strong, low stretch rope which is perfect for halyards on sailboats.
How we chose this particular product:
When we decided to start carrying rope and line, we knew we needed some of the new high-tech/low-stretch line for halyards. Michael Storer and other designers we represent specify the stuff. The problem was that we did not know squat about all the different types. There are so many names like Kevlar, Spectra, Dyneema, Technora, Nomex - the list goes on- that we had to have some help. So we did what all denizens of the internet do: we looked in Wikipedia.
Aramids, we learned, are a class of strong fibers that include such types as Kevlar, Nomex, Twaron and Technora. Besides the low stretch quality we are after, they offer high resistance to heat and organic solvents, but don't have good resistance to ultraviolet radiation. While these fibers have good abrasion resistance, they don't do quite as well when repeatedly stretched over a sheave or block as this next family of fibers.
Ultra high molecular weight polyethylene
is a thermoplastic that has very long chains
that can be fashioned into very strong fibers. The chemical structure (see diagram at left) can contain millions of atoms which makes these hydrocarbon chains very long indeed. But two specific characteristics of this fiber make it more attractive to boaters than the Aramids: it's high UV resistance, and it's ability to run repeatedly over smaller sheaves.
The most common brand in the US is Spectra
which was developed by Honeywell, Dyneema, however, was invented by Royal DSM (Netherlands) in 1979 and they currently have the largest production facility for UHMWPE fiber in the United States.
But raw Dyneema is not easy to work with. First it is slippery, as most polyethylene is. It also needs a little protection. These problems are solved by the Pelican Rope folks by braiding a Polyester cover over a core of Dyneema. The combination makes a perfect rope for halyards on sailboats - it looks nice, works like any other rope and it stretches less than anything else.
Here is the Pelican boilerplate:
Pelican Rope Works KRYPTON-D consisting of a polyester sleeve covering a braided Dyneema core ( a unique high performance UHMPE). Extremely high strength. Virtually no creep. Excellent flex/fold characteristics.
||AVG TENSILE STRENGTH (lbs.)
(per 100 Ft.)
|Elongation at Break
Red and Blue Markers
The exceptional strength and light-weight of Dyneema® fibers allow for the manufacturing of ropes with very special characteristics. Successful applications include mooring and towing lines, offshore positioning ropes, yachting lines, commercial fishing ropes and roundslings and arborist lines. The Dyneema® grades used for ropes are SK60, SK65, SK75 and SK78.
A rope made with Dyneema® is as strong as a wire rope, with the same diameter but only about 10% of the weight per meter. A new rope made with Dyneema® has a low elongation to break of approx. 6%, falling to 3.5% in use. As the elongation decreases, the breaking strength of the rope increases by approx. 10%, as load-sharing between the Dyneema® fibers improves. This results in much less backlash in the event of failure. Building staggered failure into the rope can reduce this even further or eliminate it altogether.
Excellent fatigue resistance
Dyneema®, with a specific density of less than one, has a neutral buoyancy. It also outperforms steel and other synthetic rope materials in terms of both tension-tension fatigue and bending-bending fatigue.
The properties of Dyneema® are not impaired by sea water and the ropes’ breaking strength remains constant in wet or dry conditions. These ropes have good UV resistance, and are unaffected by oil or commonly used chemicals. They also show good abrasion resistance. A mantle construction to protect the rope is advisable in some cases.
Dyneema® is compatible with all commonly used ropemaking techniques, and has been tested in the following constructions:
- Wire-laid and semi-parallel constructions: These provide the best balance between strength and bending-bending fatigue. Both sockets and splices can be used for terminations.
- 8-strand plaited ropes: These are mainly used for applications such as towing and mooring, as this construction is the most resistant to mechanical damage. These ropes can be easily spliced.
- 12-strand braided ropes: In some applications this construction performs even better than the 8-strand plaited rope.
- Braided ropes: These are the first choice for yachting ropes, winch lines and other smaller ropes. The ropes can be covered with another braid and the terminations can be splices or sockets.
Dyneema® is easy to process. In order to maintain the high tenacity and low elongation, whatever the rope construction, the Dyneema® fiber must be held under constant tension and differences in path length should be avoided during processing. The contact points are very important: these should be hard, with a surface like a skin of an orange. They should preferably be rolling, and should not be worn.
Technical and commercial support
Our expert application engineers and state-of-the-art Technicum laboratory are available to support you in identifying, developing or processing the best rope made with Dyneema® application for you, based on your needs and our extensive research. We are also able to conduct a system cost analysis for almost all applications, helping you to identify the benefits of Dyneema® for your business.
the world’s strongest fiber™
DSM Dyneema is the inventor and manufacturer of Dyneema®, the world’s strongest fiber™. Dyneema® is a superstrong polyethylene fiber that offers maximum strength combined with minimum weight. It is up to 15 times stronger than quality steel and up to 40% stronger than aramid fibers, both on weight for weight basis. Dyneema® floats on water and is extremely durable and resistant to moisture, UV light and chemicals. The applications are therefore more or less unlimited.
Dyneema® is an important component in ropes, cables and nets in the fishing, shipping and offshore industries. Dyneema® is also used in safety gloves for the metalworking industry and in fine yarns for applications in sporting goods and the medical sector. In addition, Dyneema® is also used in bullet resistant armor and clothing for police and military personnel.
The Dyneema product range consists of a number of grade groups for specific applications:
- Dyneema® Yarn, a continuous filament yarn
- Dyneema® UD, a unidirectional bullet-resistant composite
- Dyneema® FR10, a fragment-resistant needle-punched felt
- Dyneema Purity®, a new, highly purified grade for medical applications
Dyneema® is produced in Heerlen (The Netherlands) and in Greenville, North Carolina (U.S.A.). DSM Dyneema is also a partner in a high modulus polyethylene (HMPE) manufacturing joint venture in Japan.
Dyneema®, Dyneema Purity® and Dyneema®, the world's strongest fiber™ are trademark(s) (applications) owned by Royal DSM N.V.
DSM Dyneema is committed to helping existing and potential customers identify how Dyneema® can benefit their business. Providing extensive technical expertise to ensure an optimal production process is part of our service. We can also provide branding and marketing support if required. By fostering close relationships with our customers and their end markets, we’re able to provide solutions that are technically superior and commercially sound. Applications in which Dyneema® is a key differentiator include: ropes, nets, cordages, textiles, helmets, vests, inserts, vehicle armor panels and medical devices.
For more information about Dyneema, click here!