I know you are all aware that masts differ in wall thickness (usual tolerance is 5%) and stiffness, but when looking to tune your mast just taking the numbers from one mast will not reproduce the same characteristics on another one if it is not the same.
This is exactly the reason why I'm following the top-down approach now.
First find the optimal mast rotation setting that sets the top of your mainsail right for nominal downhaul and mainsheet tension. = TOP
Then fine-tune the prebend to have the middle part of the sail sit right with these downhaul and mainsheet tensions and the newly found optimal mast rotation. = DOWN
Then adjust spreader rake while keeping the prebend the same to find the best reponse to gusts. This is really the last fine-tuning you do.
Of course as everything is interacting with eachother this is rather hard to get right in one try. It is better to be prepared to hone in on the optimal settings in about 4 iterations. Or by starting at the adviced settings of the sailmaker that actually made your mainsail.
Regards,
Wouter
