Page 27 - Mark Gommers "Bowlines Analysis

The Sheepshank and the Collar (a short study)

#1152 Sheepshank is an interesting structure to examine because it has a ‘nipping loop’ (2
in fact) and somewhat resembles a Bowline. However, a crucial missing component is the
collar – both bights are in free space and do not perform a U turn around their
corresponding SPart’s. Under increasing load, both bights begin to kink and fold over – and
it is theorized that at some point, the structure will eventually become unstable. This
enables us to see the importance of the collar structure and the role the SPart plays as a
bracing post for the bight. The scissor-like action of the nipping loop (a helix) is also
observed.

Load !
Load
Sheepshank (#1152)
Load

No collar

Collar

Load

The bight is in free
space and folds over –
because it is not
Effect of load stabilized by the SPart.
As the bight continues
to fold down, it reaches
a point where the
nipping loop becomes
unstable and collapses.

Nipping loop

Load

This Sheepshank has been modified so that there are now 2 collar structures. In practice, access to either Load
end is not generally possible – and so this structure is shown for theoretical analysis only. Under load,
the structure would mimic a Bowline – since both bights and nipping loops are now stabilized.

Page 26 of 59 Bowline Analysis Version 2.7a 16 July 2016 © Copyright Mark Gommers