This system has obvious merit if a kick up system is required. The cassette system also works just fine. Any conceived concerns regarding a cassette system do not seem to be any problem in actual practice. The idea that hitting the rudder(s) on any solid object when they are in the cassettes is greatly over rated. We have used them now for some two years and sailed in some fairly suspect water depths with many solid underwater obstructions and although contact has been made with the rudders none have been broken whilst sailing. At the same time, during the same events we have seen more than one set of “kick up” rudders destroyed because the kick up release mechanism(s) have been set so tight to stop them releasing prematurely if and when they were to contact weed, muddy bottom etc, and as such, to all effects they become a permanent (whilst sailing) lock down system
The drag induced by T foils on the rudders has a negligible effect on the cat’s performance and any minor drag that may occur is greatly out weighted by all the positive benefits, (particularly pitch control), gained from the foils.
To understand the way in which T foils operate one has to view their effects as a global formula and not as a two dimensional concept.