decisions in the begining of design

Discussion in 'Boat Design' started by urisvan, Jan 15, 2007.

  1. urisvan
    Joined: Nov 2005
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    urisvan Senior Member

    Hello
    ı want to design and build a strong and seaworthy cruiser. According to my intention i have some thoughts in my mind. Her length will be about 30 feet. She will not have a very high aspect ratio keel, but still she will have a fin keel. And she will have long overhangs and steep run compared to modern cruiser-racers. She will be like 1970s cruiser-racers like contessa32 and others like her. My first question is: would you suggest this kind of boat?or?
    i want to build it from wood. İf i use wood as construction material i have to use bolted keel! and i have some doubts about bolted keels! But in fiberglass boats encapsulated keel is also a choice. İt will be difficult for me to build it from fibergalss, but if there is a big difference between bolted and encapsulated keels, maybe i should change my building material.
    I have to make decisions in the begining. I am looking forward for your suggestions to ease my mind.
    Best regards
    thanks
     
  2. Eric Sponberg
    Joined: Dec 2001
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    Eric Sponberg Senior Member

    The best way to build a bolted keel to a sailboat is by the method detailed in the book "The Gougeon Brothers on Boat Construction", which has just been republished in a new and updated version (www.westsystem.com). In there they describe a bolted keel arrangement using an I-beam/keelson combination that I have used very successfully in my designs. This should be the least of your worries.

    I highly recommend this book because it describes virtually everything you need to know regarding the planning and building of a new boat.

    I hope that helps.

    Eric
     
  3. lewisboats
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    lewisboats Obsessed Member

  4. urisvan
    Joined: Nov 2005
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    urisvan Senior Member

    hello
    thanks for paying attention.
    i will buy the book that you recomended, it looks exiting.
    forgive my caprice but i insist on asking: did you like the boat type i choose?
    and i plan to do carvel-planking because it is the cheapest method for me.
    and in the framing system i didn't give an exact decision. i plan to construct with sawn frames, and i also want some longitudial stringers notched into frames. in this way i hope to have a strong hull. would it be too difficult to construct in that way? or should i do it without longitudial frames and install bilge stringers after framing and planking have finished?
    thanks again
     
  5. Eric Sponberg
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    Eric Sponberg Senior Member

    I cannot necessarily comment on the design because you don't describe what all of the different features are, only some of them. For example, how much room inside do you need for the interior joinery, and do you want simple joinery or finely detailed and highly finished joinery. One thing for sure is carvel construction over sawn frames will take up a lot of interior space (thickness of the planking plus the thickness of the frames), and a 30' boat does not have very much space. This type of construction is also heavy, and you don't say what the displacement of the boat is. I suggest that you read the Gougeon book first and see all the different methods of construction that they describe very completely. You should match the type of construction with your skills and with the type of design and the weight of the boat. One of the strip planking methods may be the best, rather than carvel planking. So read first, and decide later.

    Eric
     
  6. benmww
    Joined: Dec 2006
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    Location: crusing yacht - aussie

    benmww Junior Member

    if you are going to be cruising in your boat, the most important thing is to get out there.
    yes it's nice to have a speedy boat that can make quick passges
    seaworthiness is not an option
    it's just something that you need
    just imagine if your in a hurricane of off cape horn in a storm,
    you need to just be able to go below decks for a while ( possibly a few days)
    and just know that when you come back up it wont matter how many times she fell off waves and how many times she submarined or flipped, she is going to be structually sound after.
    on a cruising boat, going oversize doesn't hurt that much and having a good engine really pays off
    especially if your just not content with 3 1/2 knots when travelling from panama to the marqueses.
    ofcoarse if you going to be cruising in the very low lattitudes you won't have to worry about much of this, but it's better to be sure.
    I once met a friend who liked cruising greean land and antartica and so designed a boat that could go up on the ice for long periods of time with a swing keel that lifted up into the hull
    any way good luck with designing your boat
     
  7. urisvan
    Joined: Nov 2005
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    urisvan Senior Member


  8. benmww
    Joined: Dec 2006
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    benmww Junior Member

    the roberts 34 is a common choice
    If it was me i would opt for the steel construction
    this is because of the obvious durabilty of the material and the ease of repairing any damage that occurs in a grounding
    ofcoarse metal may not be a choice for you
    i would make sure you look at what your trying to accomplish wen lookinh at overhangs
    if you are looking at a certain length try an get max waterline
    long waterline also increase seawothieness as well as higher speed in medium to high wind ranges.
    but for a certain cost a boat with long overhangs will be cheaper to build for maximum room
    what ever you do just make sure that you finish building your boat but that it doesn't impact too much in your life to cause damage
     
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