Spreaders & shrouds design

Discussion in 'Boat Design' started by Ketchlover, Feb 12, 2011.

  1. Ketchlover
    Joined: Feb 2011
    Posts: 5
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: lake Michigan area

    Ketchlover Junior Member

    Are there any stats on what length boats are when first equipped with spreaders? Secondly, what is the range of the diameter size of shrouds?
    And finally, what is the range (in degrees) of the angle formed by the base shroud to mast head and/or highest tang as the shroud bends around the tip of the spreader?
     
  2. gonzo
    Joined: Aug 2002
    Posts: 15,448
    Likes: 1,014, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    There are 10' boats with spreaders. Shrouds go from 1/8" to maybe 3". 14 degrees is the usual minimum, but some racing boats with hight tensioned rigs may have 12 or so.
     
  3. Ketchlover
    Joined: Feb 2011
    Posts: 5
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: lake Michigan area

    Ketchlover Junior Member

    Thanks. A bit more clarification if you don't mind. Assuming 3/8" solid rod shrouds, what would be the likely maximum boat length found wtih these shrouds? Also, you said 12-14 degrees minimum angle on the spreader turn. What might be the maximum angle? (Only interested in shrouds that run to masthead or highest tang.)
     
  4. Perm Stress
    Joined: Sep 2009
    Posts: 554
    Likes: 24, Points: 0, Legacy Rep: 323
    Location: Lithuania

    Perm Stress Senior Member

    Diameter of shrouds is determined by righting moment and actual rigging arrangement, not by length of boat.
    Righting arm of sailboats tend to be surprisingle similar at about 0.6m maximum; So, if one 10m boat is 3 ton, and the other 6 ton, assuming the same width of shroud base, loads will be different 2 times.
    12-14 degrees is quite normal angle. Much more than 14 and spreaders start to be overly long, heavy and vulnerable.
    Minimum angle is 9 degrees, as used on Dragon class and some others, but this is already a stretch...
     
  5. gonzo
    Joined: Aug 2002
    Posts: 15,448
    Likes: 1,014, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    Multihulls may have 45 degrees on a low rig. For example a Wharram. The righting moment and sail area are what you need to use to calculate the shrouds and not the length.
     
  6. Ketchlover
    Joined: Feb 2011
    Posts: 5
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: lake Michigan area

    Ketchlover Junior Member

    Thanks guys. One last shot. (Obviously I am not designing a new boat but going after something else) Assuming pleasure sailboats to a max of 60 feet, what would the various diameter shroud sizes be? From what to what and which would be most popular? I am going to assume wire rope vastly outnumbers solid rod.

    Thanks
     
  7. Perm Stress
    Joined: Sep 2009
    Posts: 554
    Likes: 24, Points: 0, Legacy Rep: 323
    Location: Lithuania

    Perm Stress Senior Member

    Multihulls enjoy very wide staying base. And do not have spreaders like mono's do; below the hounds they often have diamonds, at no more than ~14 degrees to the mast again.
     
  8. Perm Stress
    Joined: Sep 2009
    Posts: 554
    Likes: 24, Points: 0, Legacy Rep: 323
    Location: Lithuania

    Perm Stress Senior Member

    Wire rope outnumbers rod.
    First question is too general to consider a definite, not general answer.
    Everything above about 10mm 1x19 wire rope tend to cost (many) times more.
     
  9. gonzo
    Joined: Aug 2002
    Posts: 15,448
    Likes: 1,014, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    If you are going after something else, how about telling us what you really want to know?
     
  10. Ketchlover
    Joined: Feb 2011
    Posts: 5
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: lake Michigan area

    Ketchlover Junior Member

    I'm working on a new nav product but need to know the number of different sized shrouds I might encounter in most 60 feet and under cruising yachts. And if a lot of different sizes, then what are the 3 or 4 most popular sizes.

    Sorry I can't tell you more than that right now. Read Practical Sailor sometime this coming summer.
     
  11. gonzo
    Joined: Aug 2002
    Posts: 15,448
    Likes: 1,014, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    I don't think anyone can give you a valid answer unless you specify, for example, a particular boat design. You can go to boat companies' websites and read their specs.
     

  12. Ketchlover
    Joined: Feb 2011
    Posts: 5
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: lake Michigan area

    Ketchlover Junior Member

    What would you guess the percentange of boats under 60 feet would be having shrouds of 3/8 or less?
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.