Expanding foam sandwich between plastic wrap skin on frame

Discussion in 'Boat Design' started by Quidnic, Mar 15, 2021.

  1. Quidnic
    Joined: Apr 2020
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    Location: Wales

    Quidnic Junior Member

    that is a good point, I’m surprised no one else brought that up earlier

    I have had this in mind and will have batteries and fresh water tanks as ballast

    that 70kg is the bare hull
     
  2. Quidnic
    Joined: Apr 2020
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    Location: Wales

    Quidnic Junior Member

    for the record this box should never go near waves

    it’s a canal boat maybe occasionally river in fair conditions

    but primarily it’s a camper that can can float occasionally

    only in very fair conditions this is the design
     
  3. gonzo
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    gonzo Senior Member

    Your inspirations are all fiberglass or metal boats on sturdy, road-legal trailers. They are also a lot larger than your proposed idea. They can't be built with old fences and spray can foam.
     
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  4. portacruise
    Joined: Jun 2009
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    portacruise Senior Member

    Is it possible to just convert a boxy and lightweight used boat, travel trailer, tiny canal boat, or Lifeboat of some kind? Asian junket boat construction? Some may be available at very low cost or low cost construction, or free? Just in case you haven't considered those or other possibilities, and what would be involved, already. There are some very bright people on this forum, who might be able to suggest some other way of doing this, or something similar, although it may require compromise of your exact SOR, as many have already advised.
     
    Last edited: Mar 26, 2021
  5. gonzo
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    gonzo Senior Member

    A plywood boat can be built in one day .
     
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  6. Quidnic
    Joined: Apr 2020
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    Quidnic Junior Member

    Excellent suggestions yes absolutely

    this is the sort of design I’m working to achieve

    a lightweight wood stove is the only thing inside, everything else will be removable camping equipment
     

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  7. clmanges
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    clmanges Senior Member

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  8. portacruise
    Joined: Jun 2009
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    portacruise Senior Member

    With the very low weight requirement that you need, maybe a tent pitched on a very light shell would be a consideration. If you need something sturdier, perhaps what we call a pop-up, telescoping, or fold out tow behind camper in the USA- might be fitted to a lightweight shell or pontoons.
     
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  9. Dejay
    Joined: Mar 2018
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    Location: Europe

    Dejay Senior Newbie

    Does it really have to be a camper on a car trailer? Or do you just want to be able to pull the boat out of the water onto the beach / land. You could do that with a winch and an makeshift axle. For ultra-lightweight you'd want more expensive foam core.

    Do you have any kind of budget? In any case I think wood is always cheapest.

    Last year there was a vendor selling 6mm outdoor okume plywood for 6€/m², but I believe there is a shortage right now. Marine okume is about 28€/m² from what I find online.

    Can you scrounge up some plywood? Or wood? If you have a car and a trailer I'd start looking around for waste or leftover on construction sites and politely ask. Maybe some house needs demolishing and you can get some floor planks. Strip planking could be even cheaper but heavier and more work. I think wood is the proper way to build a shanty boat.

    I'd look for plans for simple plywood houseboats. Or a used motor boat that you can convert.

    Also consider how you going to power it. The bow you sketched (inspired by #43? Jon boat?) is I believe not efficient, you'd force the boat to plane which requires high power. A bow shaped like a flat bottom skiff or canoe should be more efficient.

    If you make just the hull longer you gain efficiency and can use a smaller motor and need less fuel. I'd make the actual hull more like 6-9 meter long but keep the "hut" small / not the entire length. The extra length would just be a lightweight skiff.

    Then I'd build the actual hut out of rigid PU foam with a bit of fiberglass and some wood frame. Not very tough but light and repairable and cheap. Especially if you can get it second hand.

    I also share your concerns that things are going to get harder in the coming decades. The UK is I believe preparing for that. But the people are going to get squeezed.

    My plan is still to build a solar powered trimaran with lots of glass solar panels and a modest battery and electric motor and water maker to achieve independence. But I haven't gotten much further than you :)
     
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  10. portacruise
    Joined: Jun 2009
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    portacruise Senior Member



    Quidnic, the waterbed #12, might have some useful ideas on how to approach your project, 75 kg and a bike can tow it!
     
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  11. Dejay
    Joined: Mar 2018
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    Dejay Senior Newbie

    I'd be curious what others can advice on planing vs displacement for a shanty boat. I always forget about planing since I'm looking for very low power.

    How fast can you go with planing for something like a 6m long "Jon boat" with a cabin? What kind of motor do you need? How much fuel? How energy and cost efficient is that?

    I figure with boat that has to plane you're stuck with relatively high power requirements and cannot row or sail. A displacement boat can be driven efficiently at low speeds with any power.

    I've looked around for the correct name for the kind of boat I was talking about earlier (flat bottom, no rocker, single chine, little flare, wide transom) and it is a "Carolina Dory".
    They seems to be quite power efficient at both displacement speed and semi-displacement. It's easy to build. Spira has some designs but unfortunately not stitch and glue. The smallest he shows with a cubby and a cabin is the 18' [5.5 M] Carolinian Carolina Dory see photos and his youtube channel. The longer 24' Key Largo Carolina Dory, 27' Bahaman Carolina Dory, 30' Key West Carolina Dory are still trailerable but would require a larger and more expensive trailer and car. I think they would need to be that big for acceptable long term living. Upside is that these carolina dories can also work offshore on the ocean for fishing. Or traveling around the UK.

    If you can scrounge up plywood they might be a good idea for you. Although the designer would probably object to them being called shanty boats haha. But you can build them out of exterior grade plywood and 4x2 construction timber or also with planking. You'd have more space on deck and capacity to carry weight for food and water and replacement parts etc.
     
  12. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    They are not built for offshore ocean work but for the shallows in the sounds.
     
  13. clmanges
    Joined: Jul 2008
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    clmanges Senior Member

    Dejay wrote:

    "I'd be curious what others can advice on planing vs displacement for a shanty boat. I always forget about planing since I'm looking for very low power.

    How fast can you go with planing for something like a 6m long "Jon boat" with a cabin? What kind of motor do you need? How much fuel? How energy and cost efficient is that?"
    --------------------------------
    Speed doesn't seem to be a requirement of Quidnic's project; he mentioned powering it with a sail, but in his own words, "... primarily it’s a camper that can can float occasionally". I think wind resistance would preclude his design from planing, regardless of power. According to his build requirements, it would also be too light to support anything close to that kind of motor.
     
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  14. Dejay
    Joined: Mar 2018
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    Location: Europe

    Dejay Senior Newbie

    Hmm right, a sailboat. Sorry I somehow skipped the reasonable set of requirements. They seem impossible so Quidnic should specify.

    Would a sharpie with a centerboard be the appropriate design for a flat bottom sailboat with shallow draft? They seem to have the same type of hull but with rocker and are "essentially dories optimized for sailing".

    Do plans for a planing Box / Jon Boat meant for live-aboard exist? It seems any sane designer would adopt a displacement hull design instead.

    ---
    For the "attach wheels to boat" requirement you could build a flat bottom boat could be build "around" a road legal trailer. This could work for a small camper.

    Ok this is a really stupid idea but I like it haha:

    You could also make a larger "trailerboat" that could carry a box truck / RV.
    The box truck serves as the living area for example a 3.5t iveco daily with a 4x2m box.
    A 1-2t trailer might be enough as long as it's long enough (8-10m). It's frame would become a structural part of the boat and provide a bit of ballast. You might also be able to make the trailer axle detachable once in water.
    It shouldn't be a legal issue modifying a trailer to look like a boat, as long as it still works like one. But for optimal results the trailer would have to be custom build to fit the shape of the hull and the wheel wells not interrupting the water line.
    For stability this would probably require outriggers that fold out.
     

  15. Dejay
    Joined: Mar 2018
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    Location: Europe

    Dejay Senior Newbie

    Oh when I looked into velomobiles for the idea of a velomoboat camper I sketched this silly idea. I believe in europe a velomobile with electric motor can technically be 4m long and 2m wide so you could make a kind of "velomovan" to live in. Unfortunately the mechanics of a velomobile are exactly as complicated as a car so it's not easy. But you could design this to float. You could even design the suspension to lift the wheels out of the water. It would be the most "legal" vehicle to live in that you don't have to pay any tax or rent or insurance for. And you could even drive on bicycle paths in the forest.

    Velowohnmobil v4_3.jpg Velowohnmobil v10.jpg
     
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