Difference concept of cruising catamarans

Discussion in 'Multihulls' started by AdrianN, Apr 10, 2023.

  1. AdrianN
    Joined: Mar 2023
    Posts: 13
    Likes: 2, Points: 3
    Location: Europe

    AdrianN Junior Member

    Hi All

    It's taken me a while (and I was distracted by other projects)... I made the hulls a bit wider (10.5:1) and shortened the battens of the sails to 6.5 meter, which reduces the sail area to 160 sqmt

    @guzzis3 you mentioned a crab claw. I like them, but how do you reef them? Assuming the original sail area we're taking about one 200 sqmt sail, not sure how the can be handled?

    Regarding sails I was also considering a Flettner-rotor, maybe just on one side to try and compare. Any thoughts on Flettner-rotors? Is anyone aware of a recent Project with a Flettner-rotor on a pleasure craft?

    I was also wondering how the design process with a naval architect usually looks like? First question: How do I find one? And when found, are there typical milestone to decide if I want to continue or not (like study-plan, bidding-plan, final plan) or is this usually a lump sum and I either see it through to final plans or get nothing?


    Thanks
    Adrian



    side2.jpg top2.jpg back2.jpg
     
  2. waterbear
    Joined: Mar 2016
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    Location: Earth

    waterbear Senior Member

    Here is a relevant quote:

    To add to this you would to estimate the weight of the stuff you wish to store in the hulls (aka "basement") and how it would be distributed.
     
  3. oldmulti
    Joined: May 2019
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    Location: australia

    oldmulti Senior Member

    AdrianN. For Flettner rotors on a multihull try the following link: Project Brighter World - Epoxyworks https://www.epoxyworks.com/index.php/project-brighter-world/#more-748

    For engaging a designer most work the same way, Pay an initial amount of money for a "study" plan which will be very similar to your existing drawings but will confirm the designer is happy to deisgn and engineer a solution similar to your ideas. After that they will probably request a contract with step payments to completion. To engage a designer e-mail your existing simple drawings and asked if they are prepared to design something like this with the Junk rig. Some will reply yes, some will send a financial quote that will frighten you and someone will be realistic.

    But a suggestion, think about a secondhand cat with a rundown rig, pay a designer to draw an improved deck and keel structure for the biplane masts bases. The designer can also design the masts/sails for you. This may not be the perfect solution but you will get something close to your needs a lot faster and hopefully cheaper. Just a suggestion.
     

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  4. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    I don't understand the problem with fitting interiors to a curved hull. Also, unless you hire an old timer that uses pencil and paper, the CADD files can be used to generate any pattern you need. In fact, it will generate CNC files to cut them.
     
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  5. guzzis3
    Joined: Nov 2009
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    Location: Brisbane

    guzzis3 Senior Member

    You don't reef them as such. You run lines between the spars and tighten them producing more curve in the sail but also effectively reducing it's area. I suppose if you have spars top and bottom you could roll the sail up around the lower spar but the sail is triangular so you'd have to think about it.

    In practice once you get your head around the differences they are terribly simple and effective. The research I've seen varies. Some claim they are the best sail out there, some indicate otherwise. I would think overall they are as good or better than Junk rigs. Low C of E, cheap, lighter than a heavily battened Junk sail...
     
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