MJP68 said..
Ahhh OK, see that's quite interesting, block to block. I would never have thought that would be the way to go, I've only ever known the "bottom of pulley" method (as per the Maui Sails rigging diagram in the previous thread you linked to).
When you are at block-to-block, are you at that sail's "high wind" setting? Or in Simmer/Severne-land, is there only "normal" (block to block) and "light" (downhaul eased off a bit)?
That information certainly changes how I think about this, so I appreciate your time taken to type that out.
I'll watch that video you linked to in order to try to understand it.
Out of curiosity: if you set your Severne extension at a number "X", then put a tape measure from the top of the collar (i.e. where bottom of mast would be), at what point on your extension would your tape measure read "X"? At the top of the extension's pulley block? Or some place above that? If the latter, is that place marked on the extension somehow?
MP
When you use the numbers on the sail. Block to block is in the middle of the downhaul range. So let's consider that 0.. the starting point. From there tuning means +/-1cm which is a 2cm range. I rarely set my wave sails with positive downhaul because I am trying to use the smallest gear possible. I would rather rig down then crank downhaul. With wave sails too much downhaul and outhaul makes them twitchy. They need belly. Their leach should not look like a slalom sail. Cambered sails like a bit of positive downhaul.
With the dot or telltale on the sails. every brand is different. Some, the dot is max downhaul, some it's the med setting. Some have no dot, some it's a batten graphic or a logo. how are the rig it until it looks right crew gonna rig my simmer sails. there ain't no dot.
It's typical to see people just crank the downhaul to the dot and beyond regardless of what the designer intended.
With the severne ext.. it honestly does not mater so I've never done it. because the downhaul numbers suit the mast and extension as part of the system. The severne team spend 12 months testing the sail and coming up with those numbers. let me say jaeger and co are far better at this stuff than anyone in this thread. Which is the point, using an out of spec mast and or extension means the numbers don't work anymore..
what I can say is it's easier to go block to block on the simmer than the severne. Severne wave sails have more skin tension than simmer.
severne do the maths for you they write the extension number on the sail. For eg 8cm.so you set the extension tov8cm and move on I also like ezzy's idea of the strings. All of these things are done to make rigging as fast and easy as possible.
The reason I'm keen to measure extensions is so we get an understanding of which extensions measure the same so we can mix and match with knowledge.
are Slalom mast better for slalom sails ,? the wall on the severne mast is defiantly thinner ,does this give a quicker 
