You just have your certification revoked my dear Berny. Look more closely at the total setup of the pole including the bridle strut and mid pole support lines.
The pole is indeed under small bending stresses due to the small amount of prebend, but these are not significantly compared to the other loading.
This is a result of the compression load and the pole being lifted at the middle while the outer end is being pulled/held down causing it to bend and the point at which the bend changes direction, the point of maximum load, is at that saddle.
You are talking about a buckling failure mode here, HOWEVER the pole at the saddle is supported in all directions but the bridle strut, pole itself and the mid pole support wires. Ergo the compression forces put on the pole by the spinnaker are NOT taken up by the pole in bending but by compression loading in the bridle strut and tension loading in the midpole support wires.
The other poster said it right. The setup is essentially a truss setup with a slight prebend in the pole to force to remove any slack and force it to try to bend more against the bridle compression strut. 2 inches of prebend is really not allot of prebend (low stresses) on a pole of overall 3.50 mtr. length.
It is however not a cantilever suetup under spi load. It will be when the owner tries to handle the boat and pushes down on the pole. For that reason it is much more weak in that role, one for which the pole was never designed.
While I may not be able to back it up with calcs, it's not rocket science, just simple logic.
True to some extend but you are still wrong. Buckling failures and truss setups are not commonly understood not even by many engineers. Sorry.
Wouter
