What you (and others) said about lee helm under spi (without CLR correction) sounds both obvious and right and is concordant with many peoples experience; however, I still wonder if it's as simple as you say because today when I discussed this very issue with an experienced I20 racer he SWORE to me that he has a nearly neutral helm under spi (as well as upwind as a sloop).
Why?
Could it be that when one raises their boards off the wind and significantly reduces the magnitude of their CLR the migration of the CE becomes a non-issue (ie, they are not seeing lee helm because they are side-slipping downwind on their broad reach)? This effect might be pronounced on cats with flat bottomed (semi planing) hulls and not observed on cats with deeper hulls - hence different sailors observe different amounts of lee helm. Also, at speed, couldn't the rudder/aft hull be generating sufficient lift to compensate for some forward sail CE migration (when their boards are raised)? Finally, wouldn't the very presence of a spi augment the mainsail's lift (ie, slot effect) effectively moving the aggregate CE back somewhat? (I hope my inexperience and/or naivete isn't showing too badly...).
Who else out there has spi experience on an I20: do you see lee or neutral helm? Anyone else out there on any other (non ARC/SC) spi cats ever see neutral helm?
