Shanty/House/Fishing boat idea

Discussion in 'Boat Design' started by cdubb, Dec 6, 2019.

  1. cdubb
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    cdubb Junior Member

    So I need some guidance here on what may be a misguided idea. To help you to understand this better I'll show you my three sources of inspiration.

    I stumbled upon this picture a few weeks ago and it's really ignited my imagination.

    IMG_4626.JPG

    So I dug some more though photos of old timers boats and, since I've always had a thing for junk rigs, I got to looking at the Chinese Wu Peng fishing boats (I could be all wrong on their actual name but it's the name I found along the way). The one that most caught my eye is actually a model from China too of course.

    D1979FC1-759E-48DB-9523-8D4586E85DD2-795-00000083700E76D6.jpg

    Lastly, after promptly ordering the model to sit atop my book case, I went to my fridge to get a drink and saw a postcard that has been hanging on my fridge's door for 6 years.

    IMG_4646.JPG

    At that moment my mind combined these three images into one and the result, to me, was pretty badas$. It manifested itself into a low tech, low cost, trailerable, wooden sport fishing boat with a small aft cabin for one (maybe two if we're friendly) and a large unobstructed casting platform at bow. I figured some rough dimentions in my head, 20' in length 8 foot of that being a cabin, 8'6" beam to be road legal and somehow 6'4" of head room. I figure hull type to be something simple, think a scow or barge or jon boat and build it from lumber yard wood or something akin to the Wu Peng (junk hull?). To keep with the idea of traditional im keen on the plank on frame method of building for the hull with plywood decks but plywood all around isn't a total deal breaker just not what I'm envisioning.

    Here's where the guidance comes in. With the plank on frame method I did some rough calculations for my pipe dream. The materials used in total were as follows and please forgive any terms I miss here.

    Sides: 8) 2x12 with a 45* angle on the bow
    Bottom: 70) 1x4x8'6"
    Frames: 10) 2x6 with 1x4 scraps for gussets
    Stern: 4) 2x12

    I wasn't too upset at the cost of lumber from a big box store but the weight is one thing I need help with. Bare hull without fasteners crosses the scales at around 1700-1800 pounds and I figured another 1500-2000 pounds with the cabin and decking that's Not including a 275lbs me, motor, fuel and gear. With a dry weight of pushing 4000lbs @20 foot long the thing is a bit of a pig. I don't expect this thing to be quick but it atleast needs to be able to get out of its own way

    So question #1
    What kind of horse power to get it to say 10 knots?

    Question 2.
    How does my hull lumber list look and are 2x12s overkill for an inland boat?

    Question 3.
    Will pressure treated lumber coated on all sides with epoxy resin and marine paint be suitable for this application? I don't expect this to be passed down from generation to generation (although I wouldnt be upset if it managed to). Resin doesn't bother me it's glass cloth I don't like working with.

    Question 4. (Really the biggest one)
    Will it float and will it float the right way up? The key to this idea is the cabin, I'm 6'2" tall and I want to not have to duck and hunch like I have in every other cabin I've been in so that headroom is really a key.

    Question 5.
    (Really it's a request)
    Any other calculations, photos or advice you can add would certainly be welcome.

    Sorry for the long post, hope to hear from you soon!
     
  2. fallguy
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    fallguy Senior Member

     
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  3. fallguy
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    fallguy Senior Member

    There are so many problems with your idea it is hard to reply.

    First, there is no low cost boat.
    Second, okume ply and glass is how to get it lighter and foam lighter still.
    ...forget green treat; it is never used in boats...
    ...aft cabins result in too much stern weight for this class of boat...

    Here is something close. Don't be fooled by the opening line on HP; it will run on 25hp.
    GT Cruiser 23 (GT23) - Study Plans https://bateau.com/studyplans/GT23_study.php?prod=GT23
     
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  4. fallguy
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    fallguy Senior Member

    By the way, in order to build a very high no duck cabin; it has to be ultra low weight above the sole to avoid the center of mass getting too high. Foam sandwiched glass panels are the best means to achieve that or you could try thin okume.

    if the center of mass gets too high the vessel will become dangerous and also very easy to rock and become uncomfortable at sea
     
  5. TANSL
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    TANSL Senior Member

    I know what you mean and I agree but it should be good to remembar at this point that a very low CoG can make a boat dangerous and unconfortable at sea. Boats are quite complicated artifacts.
     
  6. fallguy
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    fallguy Senior Member

    Does the statement apply to this design? Clarity is important for the OP; not me.
     
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  7. TANSL
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    TANSL Senior Member

    @fallguy, of course that statetement is applicable for this design, perhaps to a greater or lesser extent than in other cases but, why not?. If the OP considers it convenient, and provides me with its SOR and its forms, I will explain how and why it can be applied to his design. But notice that both, you and me, have used the term "can be", neither of us have said "will be".
     
  8. cdubb
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    cdubb Junior Member

    Thanks for the replies,

    Well I can't say I'm shocked to hear that there's some issues with the idea. I drew up a rough sketch to try and help you guys that know what your doing see what I'm trying to do. It's not to any sort of scale but it will get the idea across.

    I had similar concerns with weight and height hence how I drew it up. My question is with half the cabin being intergrated into the hull does that clear up the high center of gravity issue?

    Also:

    2x12s are over kill so would a 1x12 be more suited? That would offer some major weight savings.

    Pressure treated lumber is out. What kind of box store lumber would work?

    Would the issue of the aft cabins weight be something that could be solved with ballast?


    IMG_4647.JPG
     
    Last edited: Dec 6, 2019
  9. cdubb
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    cdubb Junior Member

    Any guidance is welcome but what exactly is a SOR and its forms?
     
  10. TANSL
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    TANSL Senior Member

    @cdubb, honestly, I think that we are going to put you in the middle of a discussion, an exchange of opinions, that will interest you very little and that will be impractical for you. If you describe what you want to do with your boat, in what type of water, the boat equipment, speed, autonomy, number and type of tanks, hull and superstructure material, (that is, if you give us your SOR) ... we can tell you if the boat is suitable to what you intend, if the CoG is higher or lower than it should be and things like that that do will interest you.
    Sorry for giving this thread a little useful horientation for you.
    Oh yes, the shape of the deck and some cross section would be very useful for the opinions that might come.
     
  11. fallguy
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    fallguy Senior Member

    No.

    Ballasting HERE reduces freeboard and increases wetted surface area and creates significant drag which in turn requires more horsepower.

    There are reasons you don't see boats like this one. There are design constraints on boats. You can build outside those constraints and then suffer the consequences.

    Your design would probably perform very poorly. Slow, very slow, poor fuel economy, etc.

    look for something close, but move away from the casting deck forward or plan to go bigger to accomodate it
     
  12. cdubb
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    cdubb Junior Member

    20' in length, 8'6" beam scow

    Purpose: A mobile fishing camp/fishing platform/house boat. Unlike a true shanty boat that rarely moves or is used as a mother ship, this boat would be fully mobile, akin to say a pontoon boat. But must be trailerable.

    Water type: Inland lakes, cannals and slow moving rivers. Chain of lakes in Florida springs to mind of a prime place for this boat.

    Engine/speed: Some kind of outboard, exact HP hasn't bee figured out yet. I'm guessing no less then 25 no more then 100hp. Console steering and controls would be a must.

    Equipment: Fishing gear and tackle, provisions to last one person a week, stove or grill. I also came across a shower/toilet combo meant for sprinter van conversions that's like 30x48" I would like to incorporate into this build so some plumbing. Minimal eletrical components, aside from nav lights and bilge pumps, maybe two outlets so battery bank would be small. Also would need shore power and solar panels. No refrigeration or climate control onboard.

    Autonomy: Be able to support a person for a week without having to resupply with minimal accomdations.

    Tanks: 1) fresh water tank 100 gal 1) grey water tank 100 gal, 1) black water tank, it's built into the shower base I mentioned earlier, porta-potty style, 20 gal I think. Fuel tanks depend on the engine size and consumption rate, could be portable or could be built it. I'd say no less than 20 gallons of fuel likely more.

    Materials: Big box lumber. That's still be discussed, I'd would like to do plank on frame. 2x6 frames and 1x12 (maybe was told earlier 2x12 are overkill) planks for the sides, 1x4s for the bottom, plywood decks 1/2" thick(?). Cabin would be built of similar materials.
     
  13. cdubb
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    cdubb Junior Member

    What about centering the cabin? That would still give me 6' on either side of it which would still be workable for me and still give me a casting platform.
     
  14. TANSL
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    TANSL Senior Member

    It is never good to place ballast, that is the last option and, in many cases (not always) it indicates a poorly made design, but you can compensate the weights of the aft structure with some bow equipment, freshwater tanks, generator set , .... or conveniently changing the stern shapes. Nothing can be said without knowing the elements that make up your ship.
     
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  15. fallguy
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    fallguy Senior Member

    Yes. This is a far better plan.

    You really ought to move away from self design. This is a classic argument here and very few builders succeed at design and build.

    Self builds run into many types of errors. The hull shape may be poor, the material selection may result in too heavy a vessel or worse; unsafe vessels.

    We have already seen you go from green treat and from 2x12s.

    Designers charge like 50-400 dollars for the class of boat you seek. Many of the problems you would design into the boat through lack of knowledge or inability would be designed out and oftentimes there are online forums that support build questions like how to install a fuel tank or how to bed and glass stringers.

    If you can't afford to pay for a stock design; how would you pay for 20 sheets of okume at $90 each? Another thing a design does often is have a written materials list from which you can develop the budget.
     
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