Roll-wrapped vs Pultrusion — Mooring Whips Unravelled
Roll-wrap and pultrusion are two primary methods used to produce fibreglass and carbon fibre tubes.
Roll wrapped
Roll-wrapped tubes are crafted by wrapping multiple layers of pre-impregnated glass or carbon fibre cloth (prepreg) around a steel mandrel.
Since the layers are applied in sheet form, tubes can incorporate weaves in multiple directions. This maximises tensile strength along the tube’s length and reinforces its circumference, thereby enhancing its torsional strength (its ability to twist without defect).
The prepreg is evenly applied on a rolling press, then wrapped in shrink tape and oven-cured.
After curing, the tape is removed, and the mandrel is released. The result is a robust, multidirectional tube with a high strength-to-weight ratio.
Pultrusion
The pultrusion method involves heating resin-impregnated glass or carbon fibre strands and pulling them through a die to form the desired shape—either a solid rod or hollow tube.
As the rod cures, it is pulled along the line and then cut to length (or weaved onto a spool).
Due to the horizontal pulling process, the glass/carbon fibre filaments can only run longitudinally down the tube’s length.
Pultrusion is best utilised in the manufacture of rods with a very small diameter, typically ranging from 0.7mm to 12mm. An advantage of pultrusion is the rods can be produced to almost any length, unlike roll-wrapped tubes, whose length is dictated by the length of the mandrel.
Why we prefer roll-wrap for tender mooring whips
For tender mooring whips, we favour roll-wrapped carbon fibre tubes with multidirectional strength that are less prone to splitting along their length. We have delivered over a thousand roll-wrapped mooring whips to superyachts around the world.
The hoop strength of a hollow tube, as opposed to a solid rod, also makes it less susceptible to buckling.
This design allows us to neatly conceal the line within the rod’s body, ensuring that the lines never get stuck or tangled.
Additionally, unlike whips that rely on a steel roller at the tip, our design enables lines to be pulled from any angle without the risk of them jumping off.