National 12

General Boards => General National 12 chat => Topic started by: Overomtimistix on 09 Apr 2014, 02:31

Title: Measurements quandry
Post by: Overomtimistix on 09 Apr 2014, 02:31
I acquired a set of unmeasured sails (approx 2010 construction) at the end of last year, and am now about to get a new mast made.
I would need to get both measured properly.
Does it make any difference whether I get the new mast the same as the old one?
What are the constraints? - I think that the sail luff and foot must fit inside the bands on mast and boom. How do the quarter mesurements affect this?
On the sail, can I just measure the distance from tack to clew and from head to tack to check actual size? Is it the straight line distance or does it folow the sail shape?
I have the measurement certificate values for my boat and the donor boat.
 
Would it make sense to make sure that the new mast fits the sail? or match the current certificate?

thanks
dan
Title: Re: Measurements quandry
Post by: NTOACertification on 09 Apr 2014, 05:45
Hi do you know what boat (sail number and section of mast the new sails were made for. The sails would have been made to fit a specific Mainsail Luff length ( though this is marginally flexible ) It would be good to know what this dimension is.

If you have no information if you put the new sail on the lawn and hold the head and tack and pull until the sail is just taught (no wrinkles) and measure the length. This would give you a pretty good idea of the luff length you need to go for.

If you contact the sailmaker who made the sails he hopefully could advise you of the mast section the sail was made for and also the luff length.  

On the new mast the distance from the top band to the gooseneck can be slightly longer than the sail luff measurement, I used to advise that the extra length should be around 50 to 80mm.

If you are able to measure the width on the mainsail, see Class rules, this would enable you to work out roughly where the band on the boom needs to be.

Hope this is a help but if you want more information either ring or email me. [mail=ntoa@ndirect.co.uk]ntoa@ndirect.co.uk[/mail] 

Kevan Bloor - Certification Officer (ex Alverbank Sails)
Title: Re: Measurements quandry
Post by: Overomtimistix on 10 Apr 2014, 01:21
Thanks Kevan,
From the measurment certificates of my boat (3342) and donor (3122)

    Boat No    3342     3122
    Luff           5429     5466
    Foot          2220     2182  
    1/4            2135     2031
    1/2            1675     1686
    3/4            1085     1125
    Main area  6.027    5.963
    Jib area     2.373    2.437
 
I shall ask P&B if they recorded the luff and foot measurements, and try to work out the actual measurementsat the weekend.
Title: Re: Measurements quandry
Post by: NTOACertification on 10 Apr 2014, 03:13
Dan
Some futher info;

The certifcate records show that 3342 had an original certificated  luff length of 5476 which would be workable for the newer sails without any mods. If you measure, from the old mast, from the top Black band to the position of the gooseneck on that mast and the measurement is longer than 5466, then the same position will be ok on the new one.
 

Kevan
Title: Re: Measurements quandry
Post by: Overomtimistix on 13 Apr 2014, 10:48
Just to add to my confusion, I have measured the current mast which is 5535 mm between the bands. The luff of my new sail is 5420 mm and foot 2210 mm.