This is not true. This was the advice that the designer of the Supercat line, Bill Roberts, gave to everyone. However nearly as goood as all other designers (and therefor designs) have the spi gate at 60% of the distance between hound fitting and mast top.

In effect: It your mast is 8.5 mtr long and your hound fitting is at 6.0 mtr. then the spi gate will be at (8.5-6.0)*0.6 + 6.0 = 7.5 mtr.

This distance is also used on the F18's, F20's (inter-20) and the F16's to name but a few well know cat types with a spinnaker.

Wouter