A full understanding of the distinctive characteristics of each fibre, whether it be technical or conventional, will be the main factor for the correct choice of rope according to the on board use to which it will be subjected. As we already know, a rope is normally composed of a core which determines the mechanical characteristics relative to the elongation and to the Breaking Load. The core can be used without a cover and in this case it is called a “Single Braid” rope. In other cases, more common, the core is enclosed in a cover (the coloured external part of the rope). This cover has protective and mechanical functions relative to the desired levels of wear and tear and manageability. This type of covered rope is called a “Double Braid” rope.
The core of the rope is constructed using different types of thread such as Dyneema®, il PBO-Zylon® etc. These fibres have different characteristics which are relative to the destination of use. In a similar manner, the correct mix of the fibres which make up the different possible covers will greatly influence the durability of the rope and the efficient execution of a pre-determined running rigging.
This section is dedicated to the choice of rope and to the peculiar characteristics of the various technical fibres.
Fibers that are most commonly used for the production of ropes
Derived from the “aromatisation” of the basic fibers.
VECTRAN (LCP) is derived from Polyester (PET).
|Kevlar®||Kevlar / Twaron®|
KEVLAR® and other ARAMID fibers such as TWARON® and TECHNORA are derived from Polyamide (PA).
Two other fibers, completely different from each other in chemical composition and general technical characteristics, are today among the most important fibers. They are used for high performance applications. The acronyms that identify them are HMPE and PBO. The trade names are Dyneema® and Zylon® respectively. The Dyneema® fiber, while maintaining constancy in its basic characteristics, offers a choice of performances, as it is available in three types SK90, SK78 SK75.
LCP fibers (as Vectran) derived from PET (Polyestere)
|Comparative table of the properties of the fibers used by Armare||Tenacity||Elongation at break||Specific gravity||Resistance to atmospheric agents||Abrasion resistance||Fusion temperature|
|Polyester H.T.||7,6||12,3||1,38||Good||Very good||260|