Is it adequate for an ocean crusing?

Discussion in 'Boat Design' started by y. erhan, Dec 19, 2018.

  1. y. erhan
    Joined: Dec 2018
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    y. erhan Junior Member

    Hi, i am a novice naval architect. I try doing a sailboat design for fun and self-development. But i can't assess whether it is adequate for a ocean crusing or or not. I would ask for your opinion based on your experiences. Thanks in advance.
    Here is the some spesifications:
     

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  2. trip the light fandango
    Joined: Apr 2018
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    Location: Rhyll Phillip Island Victoria Australia

    trip the light fandango Senior Member

    It looks like you're getting the hang of the design program nicely. If the waterline is that blue line then the boat will be dry but bobbing around and slow,...safe and uncomfortable. Everything you add to the hull to make it a sailing boat will obviously effect its sea keeping, but more waterline length and a little less freeboard, more beam, and a little less rocker would help, it's like a scaled down 50 footer, it looks good though. I have a lot less experience than many on here and no qualifications, so happily choose to ignore this if you like, cheers.
     
  3. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    A boat being a three-dimensional object, it is best to show it in 3-D.
     
  4. y. erhan
    Joined: Dec 2018
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    y. erhan Junior Member

    Thank you so much for your answer (both of you). 'trip the light fandango', this answer is so valuable and instructive feedback for me. I will try to apply those advice to the hull one by one. Yes 'blue line' is water line. When i lengthen LWL and Beam, won't it cause a decrease on Comfort Ratio?
    Mr Efficiency, my first aim is to develop myself about what good spesifications of a boat are, rather than its appearance... (i feel i have a lack of knowledge about naval architecture), but here are other pictures: (i continue the design). Have a nice day.
     

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  5. fallguy
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    fallguy Senior Member

    It would be good to hear from ad hoc a/o ilan voyager.

    Perhaps you might contact them directly.

    I don't believe speed and comfort are good friends in monohulls, but this is a generalization.
     
  6. Pammie
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    Pammie Senior Member

  7. Waterwitch
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    Waterwitch Junior Member

    Your design so far is lacking a keel, skeg or centerboard. A hull form with so little lateral resistance will not sail to windward very well.
     
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  8. y. erhan
    Joined: Dec 2018
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    Location: turkey

    y. erhan Junior Member

    I am sorry fallguy, i didn't understand what/who you mean saying 'ad hoc a/o ilan voyager'. i have searched on internet but i couldn't anything.
    You are right Pammie, Gz curve is no meaning unless checking it based on some rules. Thanks for that you lead me to some informations. I have read and used it. When i calculate the STIX number, the hull drops to catagory A, but it doesn't meet Required Minimum Righting Energy :), i think i need to increase diplacement.
    Waterwitch, The keel issue is in my mind also. i think it is next thread topic:)
     

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  9. messabout
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    messabout Senior Member

    As Hoc and Ilan Voyager are forum members who are highly qualified to provide information and/or guidance for you.

    There are quite few more individuals who are both experienced and qualified. Most of them are generous with their council.
     
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  10. trip the light fandango
    Joined: Apr 2018
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    Location: Rhyll Phillip Island Victoria Australia

    trip the light fandango Senior Member

    Yes, but it will be more satisfying because you will travel faster and have more room. Study up on the best modern cruiser of that length, look at the best , study the masters chronologically, and work out why, appreciate them.. Outright speed is nearly always less comfortable, but sitting out in bad weather in a small boat when a faster craft would have you back in sheltered water hours ago would also be uncomfortable. I live near Bass Strait. Beam seems to the best compromise though, wide sugar scoop sterns, room and speed, ..or a folk boat,..
    Comfort , speed, construction,practicality/price, Choose a favourite design and start reading, volunteer in any local industry, boat yards, yacht club[?] etc for a bit, it's pretty toxic [building] be careful, if the builders are safe and keen the boat will show it... [ha?].
    One bloke here is building a trailer that helps assemble a trimaran or cat, my tri is a soft top with a huge covered space , study self righting and anti capsize measures. if your berth can take it , old tris are better, [ ha,my prejudice], over 12knots raises concentration and anxiety levels, and thrill so I plan to depower for cruising.
    It all depends on how your potential customers want to spend time.
    Have a good look at the micro cruisers, they are cutting edge compromise and mind set, mad but wonderful, on a budget.
    When you gain more experience you will be able to ask more specific questions that will pique the interest of the very experienced crew here. cheers
     
  11. Mr Efficiency
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    Mr Efficiency Senior Member

    No disrespect intended, but the boat has gone from looking like a snow pea, to a clove of garlic. Progress is being made !
    :D
     
  12. y. erhan
    Joined: Dec 2018
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    y. erhan Junior Member

    messabout, i have realized later, while i was reading other topics:). There are a lot of member experienced and eager to help, i think i will learn from they a lot of things in this thread or other topics.
    trip the light fandango, thank you again for your mentory writing. I have comprehended what you say. In local industry, i dont have a chance because those are no have any engineering backround, only works as a traditional and withdrawn... But i will find a way to learn:), when it comes to trimaran, i dont know about that anything but it is obvious that it has advantages...
    Mr Efficiency, i accept with your opinion completely:). It has no a good view for now (maybe never if i can't evolve my skills). I think i have so long way:confused:
     
  13. trip the light fandango
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    trip the light fandango Senior Member

    If your obsessed enough and enjoying it no doubt you’ll achieve your goal, Your design reminds me of a Hood a bit, your stern is a nice shape but needs some botox laterally for mine, ,but 8 metre trimarans,, well, yada yada yada,,ha good luck
     
  14. messabout
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    messabout Senior Member

    Y.Erhan a suggestion that has often been posted for aspiring boat designers is this: Design a small boat first. A 4 or 5 meter rowing or sailing boat. Don't get fancy with it. The sections need not be rounded. Suppose that the little boat will be built of plywood.

    A simple open boat of that type is a good place to start learning about what works well and what does not. Try not to depend on your computer program. The computer can calculate rapidly but it only calculates with the information that you have given it. Let us help you learn the basic considerations for a small boat first, then you can proceed to do some design work on the bigger boats.

    In case you are not familiar with the word "sections".....(there may be a language barrier) A section is the view of a crosscut slice of the boat just like the slices of a loaf of bread. The mid section of the boat is a good starting place. From there you can begin to visualize what is needed for the rest of the boat.

    Begin by estimating the weight of the boat and the weight of the occupants as well as the weight of whatever else twill be in the boat. For example your estimate of the total operating weight of the small boat might be 270 Kg. You will know that the part of the boat that is underwater must displace 270 Kg of water. That would be 270 liters. Now you can multiply the immersed area of the mid section times the length of the waterline. You will get a number of liters that must be adjusted with a number called the prismatic coefficient (Cp) Consider that the boat is not the same size and does not have the same submerged amount in the various other sections. You will soon become familiar with that concept and that Cp values vary from about 0.50 for an extremely skinny boat like a kayak up to perhaps 0.60 for a fat wide boat like a pram.

    Forgive me if I am telling you things that you are entirely familiar with. If you are not familiar with these beginning exercises, we can go from there. If you can get your hands on a copy of a book called: The Nature of Boats, the author Dave Gerr, will walk you through the whole beginning process easily. There are other books that do the same thing but not with the simplicity of Gerr's book. One such book is :Skene's Principals of Yacht Design.

    There are some mathematics involved with boat design but for a beginner the math that you learned in high school is entirely adequate. I say again, If you are to learn about boat design and principals then do not use the computer any more than absolutely necessary. A pencil , a sheet of paper, and a text book is more educational than a slick computer program.

    I certainly do respect some of the good design programs like Michelette, Delfship, Solidworks, and others. But first you need to know the design basics and why you are feeding the program the input that you have chosen.
     
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  15. y. erhan
    Joined: Dec 2018
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    y. erhan Junior Member

    trip the light fandango,yes i am obsessed with learning about boats. I have looked Hood's boats, There is little bit similarity and i liked those:)
    messabout, thank you so much your perceptible reply. There are both that i don't know and i know in your text. But philosophy about starting from simple is so useful, i accept you. I will start a small size boat design but beside this design because i cant break off this design:).When it comes to use pen and sheet, it will be hard for me, i have not been trained for use those instead of computer:rolleyes:.
     
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