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General jib size information

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  • Kbjmjrb@cs.com
    For new sailors, here is some general information on jibs. There are two major systems to describe the size of a jib. The most common is the percent overlap.
    Message 1 of 3 , Jun 5, 2008
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      For new sailors, here is some general information on jibs. There are two
      major systems to describe the size of a jib. The most common is the percent
      overlap. This is not how far the clew comes aft of the mast. It is actually the LP
      of the sail divided by the "J" of the boat. The LP of the sail is measured from
      the clew to the luff along a line that meets the luff at a right angle. Two
      differently cut jibs can have the same overlap but be of different areas. The
      second system is the number system. This is common with custom built cruisers.
      The Number 1 genoa is the sail that works well in 5 - 10 knots of breeze and a
      full main, (usually about a 150%). Subsequent genoa numbers indicate a
      reduction in size by about 10 - 15% in area and generally follow the Beaufort Wind
      Scale. For example, once white caps start to appear, then the #2 genoa goes up.
      Full whitecaps and the #3 is used. In this system, genoa usually refers to
      any sail that overlaps the main. Smaller sails are referred to as named jibs
      such as mule, lapper, working jib, and storm jib.
      The "weight" of the cloth refers to the weight of the original cloth per
      yard. A yard of cloth measures 36 inches by 28.5 inches. 1026 square inches of
      6 ounce cloth will weigh 6 ounces. European cloth is weighed in units of grams
      per square meter and they use a real square meter. The conversion factor is:
      1 ounce of American sail cloth equals 44.8 grams per square meter. Most
      cruisers have main sails and 150% jibs made of Dacron in the 5 - 6 ounce range.
      Working jibs are usually about 8 ounces. Lighter sails and spinnakers are usually
      made of ripstop Nylon, the most common being 3/4 ounce. Light air spinnakers
      may go to 1/2 ounce cloth. The exotic Kevlar or graphite reinforced Mylar sails
      sometimes are refered to by weight but it is a meaningless term. If you have
      an existing sail and want a rough idea of it's cloth weight, you can measure
      the area and weight it. Subtract about 10% of the weight to account for
      grommets, bolt ropes, and such.

      Bruce K
      Challenger # 74, "Ouroboros"
      Los Lunas, NM


      [Non-text portions of this message have been removed]
    • Kurt Messerschmidt
      Dear Bruce, This is nice information to have, for new and old sailors alike. Thanks for posting it. Continued good luck everyone with your boats and projects.
      Message 2 of 3 , Jun 5, 2008
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        Dear Bruce,



        This is nice information to have, for new and old sailors alike.
        Thanks for posting it.



        Continued good luck everyone with your boats and projects.



        Best wishes,



        Kurt

        _____

        From: columbiasailingyachts@yahoogroups.com
        [mailto:columbiasailingyachts@yahoogroups.com] On Behalf Of Kbjmjrb@...
        Sent: Thursday, June 05, 2008 10:52 AM
        To: columbiasailingyachts@yahoogroups.com
        Subject: CYOA - General jib size information



        For new sailors, here is some general information on jibs. There are two
        major systems to describe the size of a jib. The most common is the percent
        overlap. This is not how far the clew comes aft of the mast. It is actually
        the LP
        of the sail divided by the "J" of the boat. The LP of the sail is measured
        from
        the clew to the luff along a line that meets the luff at a right angle. Two
        differently cut jibs can have the same overlap but be of different areas.
        The
        second system is the number system. This is common with custom built
        cruisers.
        The Number 1 genoa is the sail that works well in 5 - 10 knots of breeze and
        a
        full main, (usually about a 150%). Subsequent genoa numbers indicate a
        reduction in size by about 10 - 15% in area and generally follow the
        Beaufort Wind
        Scale. For example, once white caps start to appear, then the #2 genoa goes
        up.
        Full whitecaps and the #3 is used. In this system, genoa usually refers to
        any sail that overlaps the main. Smaller sails are referred to as named jibs

        such as mule, lapper, working jib, and storm jib.
        The "weight" of the cloth refers to the weight of the original cloth per
        yard. A yard of cloth measures 36 inches by 28.5 inches. 1026 square inches
        of
        6 ounce cloth will weigh 6 ounces. European cloth is weighed in units of
        grams
        per square meter and they use a real square meter. The conversion factor is:

        1 ounce of American sail cloth equals 44.8 grams per square meter. Most
        cruisers have main sails and 150% jibs made of Dacron in the 5 - 6 ounce
        range.
        Working jibs are usually about 8 ounces. Lighter sails and spinnakers are
        usually
        made of ripstop Nylon, the most common being 3/4 ounce. Light air spinnakers

        may go to 1/2 ounce cloth. The exotic Kevlar or graphite reinforced Mylar
        sails
        sometimes are refered to by weight but it is a meaningless term. If you have

        an existing sail and want a rough idea of it's cloth weight, you can measure

        the area and weight it. Subtract about 10% of the weight to account for
        grommets, bolt ropes, and such.

        Bruce K
        Challenger # 74, "Ouroboros"
        Los Lunas, NM

        [Non-text portions of this message have been removed]





        [Non-text portions of this message have been removed]
      • Kbjmjrb@cs.com
        Kurt, Thanks. I should have mentioned that because the overlap is a function of the J of the boat, if you set it on another boat with a different J , it
        Message 3 of 3 , Jun 5, 2008
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          Kurt,
          Thanks. I should have mentioned that because the overlap is a function of
          the "J" of the boat, if you set it on another boat with a different "J", it
          will rate differently. So if you are buying a used sail, it might be a good
          idea to get the actual dimensions rather than the overlap size.

          Bruce K
          Challenger # 74, "Ouroboros"
          Los Lunas, NM


          >
          >
          > Dear Bruce,
          >
          > This is nice information to have, for new and old sailors alike.
          > Thanks for posting it.
          >
          > Continued good luck everyone with your boats and projects.
          >
          > Best wishes,
          >
          > Kurt
          >
          > _____
          >
          > From: columbiasailingyachts@yahoogroups.com
          > [mailto:columbiasailingyachts@yahoogroups.com] On Behalf Of Kbjmjrb@...
          > Sent: Thursday, June 05, 2008 10:52 AM
          > To: columbiasailingyachts@yahoogroups.com
          > Subject: CYOA - General jib size information
          >
          > For new sailors, here is some general information on jibs. There are two
          > major systems to describe the size of a jib. The most common is the percent
          > overlap. This is not how far the clew comes aft of the mast. It is actually
          > the LP
          > of the sail divided by the "J" of the boat. The LP of the sail is measured
          > from
          > the clew to the luff along a line that meets the luff at a right angle. Two
          > differently cut jibs can have the same overlap but be of different areas.
          > The
          > second system is the number system. This is common with custom built
          > cruisers.
          > The Number 1 genoa is the sail that works well in 5 - 10 knots of breeze and
          > a
          > full main, (usually about a 150%). Subsequent genoa numbers indicate a
          > reduction in size by about 10 - 15% in area and generally follow the
          > Beaufort Wind
          > Scale. For example, once white caps start to appear, then the #2 genoa goes
          > up.
          > Full whitecaps and the #3 is used. In this system, genoa usually refers to
          > any sail that overlaps the main. Smaller sails are referred to as named jibs
          >
          > such as mule, lapper, working jib, and storm jib.
          > The "weight" of the cloth refers to the weight of the original cloth per
          > yard. A yard of cloth measures 36 inches by 28.5 inches. 1026 square inches
          > of
          > 6 ounce cloth will weigh 6 ounces. European cloth is weighed in units of
          > grams
          > per square meter and they use a real square meter. The conversion factor is:
          >
          > 1 ounce of American sail cloth equals 44.8 grams per square meter. Most
          > cruisers have main sails and 150% jibs made of Dacron in the 5 - 6 ounce
          > range.
          > Working jibs are usually about 8 ounces. Lighter sails and spinnakers are
          > usually
          > made of ripstop Nylon, the most common being 3/4 ounce. Light air spinnakers
          >
          > may go to 1/2 ounce cloth. The exotic Kevlar or graphite reinforced Mylar
          > sails
          > sometimes are refered to by weight but it is a meaningless term. If you have
          >
          > an existing sail and want a rough idea of it's cloth weight, you can measure
          >
          > the area and weight it. Subtract about 10% of the weight to account for
          > grommets, bolt ropes, and such.
          >
          > Bruce K
          > Challenger # 74, "Ouroboros"
          > Los Lunas, NM
          >
          >


          [Non-text portions of this message have been removed]
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