Super Downhaul line is world renowned by windsurfers - the first and still the best line specifically designed for use on high load windsurf downhauls and outhauls.
Its smooth 12-plait construction, and the slippery characteristics of 100% SK75 Dyneema fiber, dramatically reduce friction in downhaul purchase systems.
Super Downhaul's unique construction and Dyneema fiber make it useful for a wide range of applications, well beyond the world of windsurfing.
• Windsurfer Downhauls
• Windsurfer Outhauls
• Windsurfer Ratchet Downhauls
• Firm and round - stays round even under extreme loading, so it continues to hold very well in V-cleats and clamcleats
• Flexible and easily handled
• Good abrasion resistance - very long service life
• High strength
• Low elongation
• Very light weight
The development of Super Downhaul —
For years Formula sailboard racers had been frustrated by the fact that the 8-Plait pre-stretched line that they used for downhaul line broke after 4 or 5 sessions due to the extreme downhaul tension required for proper and stable wing shape.
When it became available, board racers saw how durable Dyneema® was and tried using standard 12-strand Dyneema line for downhauls — but it flattened under the high loads involved and, as a result, wouldn't hold in a downhaul clamcleat.
The engineers at FSE Robline worked with racers to develop a 100% Dyneema rope what would hold well in a clam-style cleat under load.
They experimented with significantly increasing the twist of each strand and plait under very high braiding tension, and the end result was Super Downhaul — a rope that stays round - even under very high loads.
While this construction is perfect for windsurfer down- and out-hauls, it does have a down side….
The more twist you put into each strand the more elongation you get under tension....so long lengths of Super downhaul do stretch a bit.
This is not a problem with the short lengths used by windsurfers, or when you can easily make adjustments, but is not very good for halyard and stay applications.
Although Super Downhaul still stretches less than any polyester double braid, for high performance halyards and stays we recommend using FSE Robline's extra low stretch Dinghy Control, Ocean 3000, Coppa 5000, Globe 5000 Mark II, and for stays, Ocean 5000 STS would be a great choice. See Related Products, below.
Super downhaul is great, however, for high load and high wear applications.
In the non-sailing world, it is a popular "pull-start" cord for lawnmowers and outboards, etc.
Heavy on the technical side...
Dynema® is the Dutch company DSM Dyneema's brand of UHMWPE (Ultra High Molecular Weight PolyEthylene fiber), a long chain, high strength, oriented strand, synthetic fiber with very high strength as well as high abrasion resistance.
This fiber is also known as HMPE (High Modulus PolyEthylene).
Dyneema is available in a number of formulations, SK-60, SK-75, SK-78, SK-90, etc. Each progressively stronger and more expensive.
Of particular interest these days is the difference between Dyneema SK75 and SK78. Dyneema SK78 has the same high strength of SK75, but with lower creep (non-recoverable stretch).
Honeywell International produces a similar UHMWPE fiber, marketed as Spectra®