On 22/04/2019 18:01, Tim+ wrote:

A friend wants to use a tree in her garden (about 7€� diameter) and an
existing 4€�*4€� fencepost to support her hammock.

I think the tree will be okay but I have grave doubts about the wisdom of
using the fence post. Now the angle of pull will be at about 45 degrees to
the fence so its not going to pull it straight over but my gut feeling is
that this isnt a good idea.

What would be €œadequate€� dimensions for a post to support one end of a
hammock. My friend doesnt weigh much but I think it ought to be over
specced to cope with occasional abuse by offspring.

Tim

For wire fencing, you would normally take a diagonal brace down to the
ground on the tension side. If not, a lot will depend on the ground, and
how deep the post goes. In general the problem with tension applied to
an unbraced post is that the bending moment at ground level adds tensile
stresses to one side, and this is where rot will attack preferrentially.

My horse paddock has a "wavy" boundary along a stream, so that quite a
few posts have a net force perpendicular to the fence line, and it is
noticeable that these do not last so long. Also, in one long-ish snowy
winter I attached haynets to half a dozen posts (also applying a similar
bending moment). I had to replace them all in the next year or two.