There are other and better ways to prevent mast pumping. Mast pumping
is a frequency response 'harmonic' that excites the 'natural frequency'
of the mast.
How to stop mast pumping - change the natural frequency by either
changing the rig tension or change the natural frequency of the system
by 'prebending' (forward bow) of the mast.
Oscilations are better controlled by changing the mass (not on a boat),
changing the geometry (not possible) or changing either the rig tension
(causing a 'different' harmonic) or changing the 'natural frequency' of
the mast by pre-bending. Prebending so changes the inertial
characteristics and the natural frequency that the excitation
frequency (that causes mast pumping) to be so incredibly high that one
would need hundred of miles per hour wind velocity to begin such
oscilations. Typical prebend is 3/4" on a single spreader rig and
total of ~1 to 1-1/2" on a double spreader rig. Without runners or
intermediates what can one do to stop or lessen the mast pumping?
simple - tighten the forward lowers mechainically or simply tie a
lenght of line between them (parallel to the lowers) to temporarily
i9ncrease their tension which will cause the mast to bow forward which
changes the natural frequency. ..... or again touting hte
'adjustability of runners': simply apply a 'little bit' of tension
until the mast pumping (harmonic) disappears!!!!


In article , Roger Long
wrote:

If the inner stay is removable and is only there to give you the
option of having a low, more inboard rig, for heavy weather, I would
probably go with just runners and set them up whenever the inner stay
was set. The original poster though said that his mast was pumping.
That indicates a serious need for some intermediate support. I
wouldn't make the inner stay removable in his case. It makes tacking
a bit of a pain with big jibs but also provides a great hand hold on
the foredeck and the ability to have a double head rig in lighter air.

The tracks you have are a nice refinement but not something I would
suggest in the "keep it simple, keep it inexpensive" department. It
takes a lot of structure and planning to support the full strength of
the backstays all along a track even though it does spread the load
out a bit.