single spreader rig

[Brion Toss]

Hi,
Spreader location is partly about unsupported length (Euler), and partly about staying angle (Pythagoras). On gaffers, the spreaders are crowded up to make room for the throat of the gaff (unless it is on a track), This makes for a very long unsupported length below the spreaders; fortunately gaffers tend to have less compression load that Bermudian rigs, but they still need relatively stiff, heavy masts to prevent their being too, um, lively. The spreaders on Ian's schooner were almost certainly placed there with regard to a gaff rig, and you will even see such a placement on schooners that were long ago converted to Bermudian or stays'l.
If you have a standard Bermudian rig, the rule of thumb for single-spreaders is to have them about 55% of the distance above deck. This makes for a suitably stiff lower section, without the need for ridiculously long spreaders. If the mast is designed with this in mind, and you crowd the spreaders up even a little bit, you'll be vulnerable to buckling.
So, what kind of rig is this?
Fair leads,
Brion Toss