Flat Bottom Design for Landing Craft

Discussion in 'Boat Design' started by Ketchikan Bound, Jan 26, 2013.

  1. Ketchikan Bound
    Joined: Jan 2013
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    Ketchikan Bound New Member

    Hello, I am new to this forum basically because I am going to build a boat and I would like all of input that I can get.

    I have a remote cabin 20 mils outside of Ketchikan, AK which can only be accessed by boat. I will be living there permenantly in a couple of years and I will always be transporting a large amount of items such as building materials and ATV's.

    The cove that my cabin is in has a tidal range of 16' to -4' which means that at least 4 hours of the day my cove is dry.

    I am building a 7'wide x 18' long landing craft out of marine plywood and I am trying to decide on the hull.

    I know that a small Vee will ride better in the sometimes 2' - 3' chop that I get between Ketchikan and my cabin but I worry about the boat resting on the ground all of that time and the stress on the Vee.

    I have been reading about many flat bottom boats that only use chimes or none at all.

    Any suggestions?
     
  2. michael pierzga
    Joined: Dec 2008
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    michael pierzga Senior Member

    The boat type would be a GARVEY.

    Do some googling. GARVEY PLYWOOD ATV

    http://www.working-boats.co.uk/WS6.2mLC.JPG

    Dhylan has a rather nice BIG BEN garvey ATV camp transporter.

    Devlin has some nice garveys.

    When you choose a design, be sure to contact the designer and tell him what the weight of your ATV is.



    http://[​IMG]

    http://[​IMG]
     
  3. Ketchikan Bound
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    Ketchikan Bound New Member

    I am sorry if I didn't make myself clear.

    I have most of the design alredy my real question is to put a Vee on or nothing at all.

    Thanks
     
  4. El_Guero

    El_Guero Previous Member

    I would say go flat and add two pontoons on the sides at about the waterline ..... ?

    Or, slight 'v' and have the pontoons where you can jack them down a little once you beach?
     
  5. michael pierzga
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    michael pierzga Senior Member

    I see...a vee is not needed if you are building a barge or punt. Both are perfectly adequate for transporting on protected water. Millions of them in the world.
    If you need more boat than barge to cover open water, then the garvey type hull is superior ..
    Its up to you !
     
  6. michael pierzga
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    michael pierzga Senior Member

  7. davhill
    Joined: May 2012
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    davhill Junior Member

    I would look at other boats in yr area serving similar purpose snd discuss with their owners. Is it intended to be a planing hull, or a barge? V section forward may ease wave action, but is mostly useful for planing type. Shallow v run aft may improve handling on faster hull but hull wont take the ground level... Bilge keels could solve that.

    However...

    A key issue seems to be yr "landing craft" description and requirement for loading heavy weights off bow. V bow does not adapt well to servicable ramps and is extremely unstable with weight at point of the bow.

    Your concern about strength is well founded. A V-section hull must be expressly designed to bear weight on its keel when it takes the ground. Simply putting V in a barge hull without consideration for the change in weight distribution is a recipe for disaster.
     
  8. Ketchikan Bound
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    Ketchikan Bound New Member

    Thanks to all for your great input.

    I am hoping to go at least 15 mph loaded through 1 - 2' with a 2,000 lb load so I will be using a 70 or 90 HP outboard.

    I am probably going to have to eliminate the V hull because of the constant grounding issue which unfortunatelly is going to mean more pounding on the bow. I will be able to shift my load back a little so the bow won't dig in as much.

    Does anybody think that runners on the botom would help it not to slide in turns and waves?

    Thanks again for the informoration.
     
  9. michael pierzga
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    michael pierzga Senior Member

    A 90hp outboard plus rigging weighs 400lbs, plus a Heavy ATV , gear and passengers makes an 18footer look a bit small .

    Perhaps you should post a sketch.

    An 18footer powered by 90hp needs substantial engineering
     
  10. Ketchikan Bound
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    Ketchikan Bound New Member

    Here is a simple diagram of the landing craft. I do not show any flare because I have not settled on one.

    There are two layers to the bottom with 3 - 2x4x16 boards running the length for structural and load support.

    Have at it please and suggest to me where it may be wrong.

    No holds Barrd...:D
     

    Attached Files:

  11. afteryou
    Joined: May 2012
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    afteryou Junior Member

    I think you better make it look a little more like this one if you want to put a load in it and cruise around here. That's gonna' pound like 'ell. I think it might be to low in freeboard as well. But I am not a designer I just fix and use them;)


    http://[​IMG]
     
  12. SamSam
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    SamSam Senior Member

  13. El_Guero

    El_Guero Previous Member

    Georgia kid is in a parka .... Alaskan kid is in shorts ....

    Are the locations backwards?

    :)
     
  14. myark
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    myark Senior Member

    This is a shape for the bottom you could use that has a slight rise in front and back bottom of hull that rocks it up when propulsion is applied and runs level with the water surface while planning.
    I know you want to make from wood and a pity you did not make from aluminum “less maintenance” then you could also plug the 1.5 ton torsion suspension that float off and on so when you are at the other side you can use your ATV to tow barge inland.
    Pictured is the 4.8 model with a 15 hp that planes with no load also the 8.m models in the work shop you can see the bottom shape and in the sea water planning with two 25 hp out boards.
     

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  15. Stumble
    Joined: Oct 2008
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    Stumble Senior Member

    You really need to get in touch with a designer. With the loads, speeds, and water temprature you are talking about a home designed boat is a recipe for disaster. And frankly if you are debating about adding a V or not to an existing design, you don't have a design you have a cocktail napkin sketch. These are the first questions you need to answer when creating the design.

    As for drying out. There are a lot of ways a Vee hull can be designed to be fine resting on its bottom.
     
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