Mike
I can see a lot of sense in your explanation of the spi sheet angle. I will definitely experiment when I go out next, unfortunately I haven't purchased a GPS but will see if I can borrow one and use it properly to butts any gains. My F16 main is currently having some work done to it so yesterday I was crewing on a Mastrom Tornado. For the past 6 yrs I've only sailed singlehanded apart from a couple of long distance races, so I'm not the worlds best crew, and in fact if I was to be honest I don't enjoy crewing that much!!
As it was I kept my mouth shut most of the time, tweaked the downhaul and jib a couple of times to appear interested but really really enjoyed the ease and grace at which the Tornado cruised around the course. The wind was around 10-12mph and was continually veering W-NW. Even when the helm lost concentration and ended up pinching the boat didn't make any dramatic complaints just a gradual reduction in speed hilst I on the over hand was left bitting my tongue hoping he would notice the tell-tales. When we were right in the groove and a small gust would come along there was no drama. The windward hull would lethargically rise up and the boat speed would increase so fluently and effortlessly it was a joy. Tacking was so boring and slow compared to the F16 and after each tack I would have to re trim the jib to avoid the leech curling on the spreader as the mast rotated, obviously not a major issue and one which doesn't occur with their newer jib I believe. The spi is big and sheet loads were heavy when going high and again everything happened as if in slow motion, gybing, bearing away, the lifting of the windward hull. The only thing which wasn't slow was our speed. At this point I would like to say that we won the race which included 2 F18's and 3 Dart 18's but as we sailed the wrong course which was all my fault due to me having a blonde moment we probably ended up last.
As for the difference between Big T and F16. The T is like an old gentleman to me, very polite and well mannered, not in any particular rush to do anything out of the ordinary apart from going super fast in any given direction. Getting it to point in that direction can be a little slow. The F16 in single handed mode on the other hand is more like a teenager, lots of mood swings, needs telling twice what to do occasionally, you can't take your eyes of them if you want them to behave. Basically a different kettle of fish all together.
However, in saying all this given a choice of which one I would most enjoy sailing then it would only depend on the type of racing involved. Round the Cans would be F16 any sort of distance racing then Big T. Unfortunately this experience has only put the F18 and F20 further back on the list of Cats I most enjoy sailing which currently stands at F16, A Class, T , Dart 18, F20, F18. I must try and get a ride on a spitfire one day to see how it compares.