Regarding measuring your headstay's length, you can't do it with any accuracy, when it's in place, particularly with a furler
overtop of it. Because the catenary (curve) induced by the foil & sail, will alter the measurement by a good bit. Assuming that you're looking to measure within tolerances of less than an inch or two.
Also, the figure given by Catalina
, is a nominal one. Different makes & lengths of tangs get used at different times, people alter the rake of their spars. Including by having the butt shaved for rake, etc. Or even have spars shortened slightly, to trim off a corroded or cracked base. This even occasionally happens before the boat leaves the production facility…
And the length of stays, & other elements of rig tune, get changed all of the time. Notoriously by racers, but by lots of other folks too. Up to, & including the length of, yes, the headstay. By a Lot more than just a few turns on the turnbuckle.
A good number of racing
boats, do it by several inches (or closer to a foot) or more. Even/especially when under sail.
The actual headstay length on a cruising boat, though, isn’t super critical. But if you want to get an accurate measurement of it's length. Take off the jib, unpin the stay, & lower it & the furler
, together, down to the dock
. Then put it under a bit of tension, & you can get a real world, accurate number.
I'm saying that knowing the exact length isn't critical, because unless your furler & jib are right up next to the halyard's sheave box, then odds are you could bob a few inches off of the wire, without it affecting much.
But since you're going up the rig, take a tape measure & a camera
with you. It'll help you to verify things, position wise. Especially that your furler’s installed correctly, & whether or not you’ve got room to shorten it. Plus the camera
will let you look at your masthead, stay, furler, & halyard
setup later on. That & also to have other folks assist you in diagnosing things. Including the above (possible) length/interference fit quandary.
Should you decide to shorten it by a bit. Then, post headstay bobbing, after tuning everything else, & having taken her out for a few test sails
; if you're helm
is squirrely, & you track it down to needing more headstay length. Then you can always add a toggle or two, or a set of link plates.
As an example of headstay length tolerances:
On my 1st boat, a Ranger
33. I needed to do some work on the furler’s lower end. Which necessitated me lowering it & the headstay onto the dock
. And in the process of doing the work, I had to take 3”-4” off of the stay, & then later reinstall the Stalok.
When I put the stay & furler up, there was zero noticeable difference in anything.
Odds are it’ll be the same on your boat. As on most boats, except racers, the sails & furlers, are cut/setup with loose enough tolerances to accommodate sails from various makers (including warehouses half way around the world). And on boats which vary dimensionally, from one lot to the next. For no two of them are exactly alike.
Sails are cut to fit boats, not the other way around. Which is why sailmaker’s traditionally come down to a boat & measure her, prior to making her a new sail.
And sailmakers modify sails all of the time. Such makes up a good percentage of their business.
Plus, & cropping 3”, or even 6” from the head
of a jib, takes less time than does rolling it up, & putting it into it’s bag for transport. And is exceedingly common to boot.
: DON'T believe anything I say. Go out & read/research things yourself. Then try'em out. Take stuff apart, & don't fret if you break gear. You'll learn to fix it. Sail... A lot.
And: Get to know marine professionals, as friends.