Eliminating Running Backstays From A Design

Discussion in 'Boat Design' started by LFH Fan, Feb 12, 2008.

  1. LFH Fan
    Joined: Feb 2008
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    LFH Fan New Member

    I am interested in the Restricted Sail Area Cruiser design by L Francis Herreshoff (Sensible Cruising Designs). While it is not a small vessel I would want to rig it in a way that is most condusive to single handing. The intention is to be able to sail on and off mooring and anchor and to be single handed even when I reach a substantial age.

    The design calls for running backstays and a slightly overlapping jib. My thoughts are towards making the jib self tending and to see of there is a way to safely and efficiently eliminate the need for the running backstays.

    Assuming that cost is not a problem how might this design best be rigged for single handing?

    Any thoughts?
     
  2. Brent Swain
    Joined: Mar 2002
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    Brent Swain Member

    Jumper struts between the masthead and spreaders, you know that little triangular set of spreaders you see on some traditional boats, was the standard way to eliminate runners. It stifffens the upper panel for and aft , taking the strain down to top of the aft lower shrouds. Older Thunderbirds have them.
    Brent
     
  3. LFH Fan
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    LFH Fan New Member

    Thanks Brent.

    I assume that using the original use of running backstays was preferable to the jumper struts. Would the use of more recent materials in the mast, whether aluminum or carbon fiber, also help mitigate the need? What might the downsides to the jumper struts be? That is, in my ignorance of rigging, why were running backstays originally chosen over jumper struts for the design?

    Regards
     
  4. Tad
    Joined: Mar 2002
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    Tad Boat Designer

    The Restricted Area Cruiser already exhibits jumpers and runners in a 7/8ths ketch rig. LFH had some funny ideas in his rigging plans.

    In this case the runners are opposing the headstay load and the jumpers are supporting the masthead. Modern rig design might call for spreaders and shrouds raked way aft (to oppose the headstay load) and no runners or masthead spinnaker. This increases the vertical loads on the shrouds (tension) which would not be a good thing for a traditional wooden boat. But if you are going to cold-mold her, modernizing the rig may be possible.

    A change of tube material will not change the support requirements, the rig has to be designed as an entire sub-assembly. As I stated above it must also be designed with the vessel structure in mind.
     
  5. Brent Swain
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    Brent Swain Member

    Jumpers support the top panel between the spreaders and the masthead , where the staysail attaches. The only drawback is they may snag a genoa if it passes over them and they are not smooth enough, if we are talking about a cutter rig with jumpers to support a staysail.
    Brent
     

  6. Tad
    Joined: Mar 2002
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    Tad Boat Designer

    We aren't, see Sensible Cruising Designs by L. Francis Herreshoff. The Restricted Sail Area Cruiser carries a single jib with the headstay run to the root of the jumper struts and opposed by running backstays. There is a triatic stay from the masthead but no backstay run to the deck.
     
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