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Couple of "beginner" questions

 
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Thurston



Joined: 08 Jul 2013
Posts: 101

PostPosted: Wed Dec 04, 2013 9:04 am    Post subject: Couple of "beginner" questions Reply with quote

1. Where are you supposed to tie off or loop the bottom end of the uphaul line? I usually just loop it around the mast near the U-Joint but seems like there is probably a better way to do it.

2. What does the third number on a mast requirement mean? 460/25/25:

460 = 460 cm mast
25 = IMCS value (flexibility, higher number is stiffer)
25 = ???
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bred2shred



Joined: 02 May 2000
Posts: 989
Location: Jersey Shore

PostPosted: Wed Dec 04, 2013 12:43 pm    Post subject: Reply with quote

1) Rig your sail completely, then take the loop at the end of the uphaul and place it over your base extension so the extension passes through the loop and the uphaul is pulled up against the sail. Then connect your rig to your board/u-joint. The sail keeps the loop from being pulled up, the board keeps it from being pulled down. It's that simple.

2) Third number is probably the "MCS" number. MCS is the "Mast Check System" (the old system). IMCS is the "Indexed Mast Check System". IMCS basically normalizes all mast stiffness measurements to a 460 mast length so when you look at any mast, you get an apples to apples stiffness comparison. If your mast is older, it may have both MCS and IMCS numbers printed on it. In the example you gave 460/25/25, the third number is the MCS number. This makes sense since for a 460 mast, the MCS and IMCS numbers are always the same.

The important thing is to make sure the length and IMCS numbers match you sail's requirements.

sm
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kmf



Joined: 02 Apr 2001
Posts: 503

PostPosted: Wed Dec 04, 2013 12:53 pm    Post subject: Reply with quote

There is a good explaination of mast stuff here...

http://www.windsport.com/gear_article?news_id=107

KMF
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U2U2U2



Joined: 06 Jul 2001
Posts: 5467
Location: Shipsterns Bluff, Tasmania. Colorado

PostPosted: Wed Dec 04, 2013 2:28 pm    Post subject: Reply with quote

There are 4 sections, top left that deal with masts.

http://peterman.dk/start-windsurfing-samlet-gb-dk01.htm

the 2nd number you ask about is MCS, forget its there.

What you want to see what the mast really does is the percentage of deflection , that will give you a percentage of deflection at 1/4 & 3/4s length, subtract the 2 numbers,


ie 78 minus 65 = 13

is a constant curve flex top, Sail lofts design their sails with a mast bend curve, so it should be mast sail compatible, otherwise too stiff or too soft either top or bottom. there percentages are not always listed my the mast company, if requested most will supply them, they don't want you to have too much information, else you may purchase something else,
as well they think you are not smart enough to understand what they are, and in fact tell but a portion of the mast curve. percentage of carbon, its orientation AND MORE ALL ADD TO THE STIFFNESS.

uphaul line:

yes around the mast or the mast base, not much in the way of option. Some sails have a hole where the rope can be routed thru and then secured as above, Just need to do the job of being there and otta the way.

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