1/2 size, offshore Thames Sailing Barge/Garbage scow/liveaboard

Discussion in 'Sailboats' started by misanthropicexplore, Aug 1, 2018.

  1. misanthropicexplore
    Joined: Apr 2018
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    Location: Upper middle Missouri River

    misanthropicexplore Junior Member

    My wife and I were talking about the Pacific Garbage Patch (PGP), and hit upon an odd idea. The PGP is almost all floating plastic. Recyclers buy mixed plastic scrap for $260 a ton.

    If you could live on your boat and gather 20 tons of plastic a month, you could just barely make a living for a couple, as long as you had no fuel costs. So what is needed is sailing cargo boat that could be handled by two people, and hull about 20 tons of payload.

    Some back of the napkin number crunching lead to something very much like a half size Thames Sailing barge:

    steel
    53' LOA
    12' Beam
    5' deep,
    leeboards
    2100 ft2 of sail*
    20T cargo
    2-3 crew

    The center section (about 2o'-24' long) is a simple box. The bow and stern are a bit more complicated, but a simple 5 panel build should work to approximate the spoon bow and wineglass transom, making up the rest of the length. I figure make the "cargo bay" 8' x 24' with 2'x5'x24' airbox on each side. They're airboxes when you're fully loaded, and a water ballast tanks when you are empty.

    Going off of sectional barge scantings (which are about the same size of boat, though used in a different way in a different place) 1/4" plate and 2"x3"x1/4" angle section on 16"-18" centers seems to be about right. That seems to make a bare hull of about 10T. Add 5T for engine, rigging, stores, etc. and the boat come in at 15T. That seems about right for 53'x12' DIY steel boat. Add 20T of cargo and now you have 35T of total mass to get home.

    To get get out to the PGP in a week, you need 6 knots and that means you need the SA/D ratio between 16 and 20 at 35T of displacement...and that takes 1700 to to 2100 ft2 of sail. That seems like a lot of sail for a small crew to handle, and this all only works if you can do it on the cheap, so maybe a junk rig? Maybe a DIY Dyna rig? The reason, btw, for the leeboards and flat bottom is because it's the cheapest way to build strong and simply, as well as the ability to offload to a truck on the beach instead of paying port fees.

    Thoughts please?
     
  2. JamesG123
    Joined: Mar 2015
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    JamesG123 Senior Member

    You should first research and figure out how you are going to collect your "catch" before worrying about the boat. Unless you have?

    AFAIK the PGP isn't like a landfill in the water, but mostly very small particles and pieces of plastic scattered over of hundreds of km^2 with only a few bits per meter. How do you collect that in a reasonable time frame without also by-catching marine organisms? Most of the proposals I have seen are pretty far-fetched ideas of using km wide booms and wave action to concentrate the junk enough to make it worth pulling out of the water. This will have a practical impact upon you design.

    BTW, plastic floats.
     
  3. misanthropicexplore
    Joined: Apr 2018
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    Location: Upper middle Missouri River

    misanthropicexplore Junior Member

    Mostly this is an excuse to paper design a boat. :) Coal sells for about $50/ton, and mixed plastic is actually an excellent coal substitute: it produces more energy per ton, and costs less to scrub the stacks after, and huge number of plants are already burning it right now. Petroleum/coal companies have huge capital, so I suspect if there was money in doing this large scale, Peabody Energy would have already made a 10,000T trawler factory ship that could collect, shred, wash, and pelletize the plastic for power plants. So large scale, there's probably not any money in it. If you are trying to get all the plastic but not the sea life, it's a complex operation to make large scale and automated. There's about 1/4 ton per square mile of ocean.

    Recent studies have found it's hardly micro plastic at all, though. Less than 5% is smaller than a 1/4", about 30% is larger than 20". Actually about 50% of it just ghost nets, wrapped around other large plastic fishing gear. A huge trawler would need some sort complex filtering system. But, an individual sailboat could just make a search pattern and grab the biggest stuff when they see it. Horizon is about 2.5 miles away on the ocean, it shouldn't be terribly difficult to cover 100 square miles a day. In theory that's 25 tons a day, however we aren't filtering it, we're just grabbing the big stuff, so I'm figuring it will average about 2 tons a day. Most likely it will be 3 days of nothing, then one 6 ton clump. I figured we'd pull it over the side with a jib crane.

    This doesn't really "solve" the problem of the PGP at all, of course. It's just a way to make a living on a boat doing something somewhat helpful.

    I am now also fascinated by the idea of this little sailing cargo boat, whether the GPGP idea works out or not, and that's why I was curious if the numbers seem in the ballpark.
     
  4. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    The Thames is a river with choppy waves at the most. The estuary can get rough, but is only a small section of it. The North Pacific, on the other hand, has very rough weather and hurricanes ( typhoons). The design should address the operating conditions.
     
  5. misanthropicexplore
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    misanthropicexplore Junior Member

    That is concern of mine as well, but since the concept only works on a shoestring budget, I'm not sure how to meet the conflicting requirements of (1.) Cheap to make (2.) Cheap to operate (3.) Cheap to crew. (4.) Can haul 20 tonnes. (5.) Safe 1000 miles off shore in the pacific.
     
  6. JamesG123
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    JamesG123 Senior Member

    Well alrighty then.

    Thats not the way it works. A company has to be able to see a return on the total investment that either produces a profit or reduces their costs. Energy companies have huge capital, but most of it is tied up in hard assets, mines, pipelines, railroads, etc.
    For them, they have to look at the costs of the boat and its support, vs the cost saving, if any from burning sea plastic, PLUS the risks of doing something new. Most established businesses with the above won't make that choice.

    Actually there is ONLY money in it at as large a scale as you can make it. Otherwise your ROI is going to be diminished to the point where you won't be much better off than a garbage pit scavenger. Your costs will always be higher than you thought and your profits lower than you hoped.

    Be careful of believing everything you read on the Internet, put there by "activists" who need to drum up alarm in order to raise money. You should be using the most "pessimistic numbers" you can find to plan with.


    You need to think bigger (esp. if this is just a paper project) not only because of the economics of it, but as "Gonzo" said, because the big ocean is really big. You aren't designing a cruiser to scoot across from anchorage to anchorage, but something that has to be designed for the mid-ocean.
     
  7. misanthropicexplore
    Joined: Apr 2018
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    misanthropicexplore Junior Member

    That's all great advice and insight, it's just not really anything I can do much with. Semitrailer portable, barge-like hulls forms, welded in a cornfield, for and fit out for around $100k, John Deere straight six diesel, owner operated, for hand picking garbage and selling it to a recycling center is close enough to my knowledge/skill base for me to being to ask questions, google, and pass judgement intelligently. If you start talking about making a real business plan to pitch to investors for a 20 person crew, a full size commercial cargo ship, multipass filtration system ,filtering millions of gallons a day, etc. I'm just not conversant enough on the topic to pass intelligent judgement.
     
  8. JamesG123
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    JamesG123 Senior Member

    Building a pirate ship to prey upon container ships from China would be more practical.
     
  9. Blueknarr
    Joined: Aug 2017
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    Blueknarr Senior Member

    Convert WWII liberty ship. Hopefully one rigged to run on coal heated steam. Should fulfill your following requirements.

     
  10. JamesG123
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    JamesG123 Senior Member

    Are there any (sea worthy) Liberty ships left besides the one museum boat? I'm not sure how hot envirowierdos are going to be about crewing a ship belching burnt plastic smoke out of its stack...
     
  11. gonzo
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    gonzo Senior Member

    One of the main problems collecting plastic, specially the smaller particles (less than 6 inches), is that the percentage of biomass will be large. Also, you will be killing a large part of the biomass, which counter to your plan of saving the planet. I am not sure there is developed technology to deal with that problem, bu $100k won't even get you started. Further, if you can't pay for port fees, how do you plan on offloading and delivering 20 tons of hazmat material? You will probably be arrested if you drive your boat and tractor-trailer on the beach. That is also assuming you don't get stuck with the trailer six feet under water.
     
  12. misanthropicexplore
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    misanthropicexplore Junior Member

    Well, again, I'm not trying to save the planet. I'm not even trying fix the GPGP. One broke dude in a sailboat isn't going to make much of difference. Used fishing nets are more than 40% of the waste, and aren't hazmat. I just wondered if it it would possible to build a small steel cargo sailer, and break even on just the maintenance costs of it, not the original purchase cost, by selling the used nets as nylon/mixed plastic scrap waste, which goes for about $260 ton. My business is contracting/house rental. I don't know **** about running a large scale venture in international waters, and I wouldn't presume to. If people with experience say it's not feasible as a business, then it's not feasible as a business. To me the interesting part of the idea was sort of modifications would be needed to the Thames Sailing Barge concept to make it a safe, small cargo boat offshore, not the business case.
     
  13. JamesG123
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    JamesG123 Senior Member

    Yeah.... not feasible. All the way around. Not at the scales you imagine.

    Interesting to think about, but reminds me more of that awful movie "Waterworld" than a good idea to try.
     
  14. jorgepease
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    jorgepease Senior Member


  15. Tiny Turnip
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    Tiny Turnip Senior Member

    Processing your large misshapes on board to get them down to a size where they will pack in the hold reasonably densely? (depth of hold? closure to stop it all ending up overboard in a blow?) weight of the above?

    Visibility of floating plastic in waves?

    Distances sailing (tacking) a course between random positions of floaters and manoeuvreing at close quarters under sail to pick up the floaters?
     
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