THE SHELLNUT

FEATURES OVERVIEW

While the Shellnut is basically a wedging device, requiring some form of constriction placement, it performs the role to perfection, exploiting every feature that the crack has to offer to achieve jamming. This ability results directly from the Shellnut’s unique design shape, being three-dimensionally rounded and completely hollow.

The dome-like rounding, apart from providing inherent ‘arch’ strength, gives the Shellnut two important wedging features. Firstly, its longitudinal rounding provides a tapering curvature similar to other ‘state of art’ curved nuts, enabling lodgement in cracks of varying angle. Secondly, unlike other nuts, the Shellnut is provided with rounding transverse to the longitudinal direction, which enables stable location in skewed* and side-flared* placements because the contact zone of nut head with rock is always substantially aligned with the central direction of pull. The Shellnut’s rounding in the third ‘plan’ aspect provides an excellent load bearing profile for the resiliently* attached sling.
*See Shellnut supplementary text.

The Shellnut’s hollow feature, apart from the obvious lightweight aspect, provides a further two functional attributes. Firstly, it enables the Shellnut to straddle local protrusions of the crack surface at the location of placement, giving optimised seating. Secondly, of equal importance, it enables the Shellnut to lock onto such surface protrusions, enhancing wedging effectiveness.

IN DETAIL

Shellnut on rope

Typical placement

Shellnut on rope

Showing resilient connection and rope profile

Shellnut on Dyneema

Showing low connection profile

Shellnut on Dyneema

Typical placement

General Handling

Handling characteristics of the Shellnut are strongly influenced by the sling type (i.e. whether nylon rope or Dyneema tape). The greater stiffness of rope, compared with the highly flexible loose weave of Dyneema, results in rope providing better Shellnut handling in both placement and removal. Rope also has better abrasion resistance in use than Dyneema, for the same reason. Therefore, overall, rope is the recommended sling material for Shellnut. The only clear advantage of Dyneema ( over rope) is providing a slimmer envelope profile for shallow Shellnut placements, where such (necessarily marginal) placements are the only possibility.

Placement & removal

Whilst the Shellnut is readily placed, best results in many cases will result by exploiting the nut’s contact face asymmetry relative to the crack shape/features. In regular ‘textbook’ taper constrictions the Shellnut’s principal attributes remain latent, and its fit will be solid but similar to that of other curved nuts. However, in the more generally found case where the crack sides may be irregular or flared, or the placement direction skewed* relative to the constriction axis of the crack, the Shellnut excels, and with experience the climber will soon be making use of such rock features, rather than avoiding them. After placement, the Shellnut should always be firmly set by a tug on the sling. Shellnut removal is best performed by first applying a side twist via the sling shank to loosen the nut before extraction.
*See Shellnut supplementary text.

Specification data

SHELLNUT 1 PRODUCT SPECIFICATION DATA

  • Nut body dimensions mm: crack size max. 20.8, nut width max. 29.0, nut length 37.5
  • Sling* length approx: 300 mm
  • Rated strength**: 14 kN
  • Weight including sling approximate: 49 g

*Slings are supplied to your choice in either knotted 7 mm nylon rope cord (tied in a double fishermans and pre-tightened to 5kN) or in sewn 10 mm Dyneema tape.
**This is the measured load at onset of Shellnut dome deformation. The breakage strength of Shellnut/sling is greater.

SHELLNUT 2 PRODUCT SPECIFICATION DATA

  • Nut body dimensions mm: crack size max. 24.1, nut width max. 29.0, nut length 37.5
  • Sling* length approx: 300 mm
  • Rated strength**: 14 kN
  • Weight including sling approximate: 52 g

*Slings are supplied to your choice in either knotted 7 mm nylon rope cord (tied in a double fishermans and pre-tightened to 5kN) or in sewn 10 mm Dyneema tape.
**This is the measured load at onset of Shellnut dome deformation. The breakage strength of Shellnut/sling is greater.

SHELLNUT 3 PRODUCT SPECIFICATION DATA

  • Nut body dimensions mm: crack size max. 27.9, nut width max. 29.0, nut length 37.5
  • Sling* length approx: 300 mm
  • Rated strength**: 14 kN
  • Weight including sling approximate: 55 g

*Slings are supplied to your choice in either knotted 7 mm nylon rope cord (tied in a double fishermans and pre-tightened to 5kN) or in sewn 10 mm Dyneema tape.
**This is the measured load at onset of Shellnut dome deformation. The breakage strength of Shellnut/sling is greater.

Additional technical info

1. Shellnuts are made and tested to the requirements of ‘chock’ Standard UIAA124/EN12270.
2. Shellnuts are produced as a one-piece solid body in Alloy 6082 T6