Regarding the mast rake and (or) leach tension I must say that there is NO right or wrong method.
It is good if class is trying to standardise the principle of leach tension method, but from my experience every one is doing the same think on a bit different way. This is the reason why you can not relay on those measurements. It is different if you measure the tension when the boat is on dolly in relatively horizontal position or with stern touching the ground?How long is spectra line, do you have hooch on halyards (wilke) or you use internal halyards (HIT) which can create big error?
Unfortunately, those measurements are only valid for personal use, i.e. you should have your system of measurement, with your data base and it is very difficult to share those data and relay on them.
My advice is:
Make spectra line long 6000mm. Normally, new north is long 6000, and new Victory is long 6010mm. Older sails are shorter due to shrinking process. Remember that they can shrink a lot!
So, measure your leach tension, always on the same way, boat in horizontal position, boom on the deck, on side.
Read the numbers, for example 33 kg .
Then you need to have up-to-date leach lengths of your sails
Sail 1=6010
Sail 2= 6000
Sail 3= 5990 mm? etc?
Then, you should have small, simple table with corrections, where basically you can see that 1cm of leach length is X kg of leach load. (1cm LL=0.5 Kg)
So, if you going out with SAME MAST RAKE, and SAME LEACH Load what you have READ on the SCALE, (for example 33 KG) it would be different WORKING load for Sail 1 then for sail 2 or 3.
So, to be on the same Working Leach Load you should apply those small corrections.
Second system is to attach tension meter on outhull, hoist the measurement tape with halyards, then adjust the leach length on exact number of your sail you want to use. Withdraw of this method is that possibility for wrong readings and measurement is bigger especially during the windy day?
I hope I have help you a bit?
Best regards,
karlo
Karlo Kuret, dipl. ing. Put Meja 14, Split Croatia