Max,

Warning: The following answer may be too Engineerese for the general
public, my appollogies in in advance.

The real value of any modern woodworking epoxy is in it's capability to
saturate into the surface of wood and the fact that it remains flexible.

Yes, an unstayed mast will have higher flexural loads than a stayed
mast, but if you do the glass/epoxy correctly it will be the loaded
element and the wood will largely just hold it to form. As it is not a
case where the wood core could flex and the glass/epoxy would not, there
should be little shear load available to cause the separation of the two.

The matrix overlay will have to be carefully designed and assembled to
achieve stiffness as and where required and then taper as required to
not cause an abrupt change in stiffness at as undesired location.

Unidirection glass tows would be and interesting way to do this, but you
must be careful to cause hard spots as the section reduces (tapers).
Any place that parallel fibers overlap, this is a possible issue.

I have had several applications that were in sunlight for many years
without exhibiting any characteristics that caused me any concern at all.

Was this rig designed to use a solid wood unstayed mast (like many old
Catboats)?

If that is the case, what do you hope to gain?

Matt Colie


max camirand wrote:
Hi group,

If one were to sheath an unstayed, solid (grown) wooden mast with
unidirectional fibreglass and epoxy (painted over for UV protection),
would the sheathing eventually embrittle and fail? I'm thinking that
an unstayed mast goes through far more flexion cycles and flexes much
further than a stayed mast.

Thoughts?

-Maxime Camirand