Thanks, Matt!



That's exactly what I needed to hear, and it agrees with my experiences this weekend. I needed to have a slightly softer mast with slightly more prebend. I could have just tightened the diamonds to get more bend, but then the harder mast wouldn't have flattened in response to sheeting. So when I raked more, while thinking about rotation, what also happened, was it slightly exposed my short mast-axis to bending load, making a softer mast, with slightly more prebend! That's why it worked. This weekend's sail went well, see post below.



So Mark as usual is right of course, you can't just lightly screw around with spreaders while thinking only about rotation, it just happened that I needed more rake, for other reasons, which I didn't initially go into in my original post, not wanting to dog on a hugely excellent sail, withoug good reason to drag it into the discussion.



Eureka!!



So, the simplified rule-of-thumb (on a prebent rig) is:



More rake gives you a softer mast by allowing you to get the same prebend with less diamond tension; incidentally it lets the mast rotate more too. Less rake does the opposite.



(Naturally, you have to understand your sail and what it needs before you change your rake.)



Anybody notice any other effects of changing spreader rake?