Building a floating island/raft from PET plastic bottles like Richart Sowa did.

Hello everybody, in a year or two I am going to start building my own floating island in the tropics like what Richart Sowa did.

You can see some pictures in the link below.
http://ecoble.com/2007/11/18/250000-bottles-amazing-recycled-mexican-island-paradise/

I will try to build it a little different keeping it 30' wide hexagonal shaped, as so to add additional island extensions and floatilla up to it like a bee's honeycomb.

I will probably use PET plastic bottles recycled from the place I am building in. They are very common source of plastic bottles.

I am looking for advice as the the build on this boat as I designing and building it different the Richart Sowa's Spiral island and Joyxsee island.

It will still be classed as an Eco boat with safety equipment standards, and the authorities will allow me to build it.

My main concern was that I am really looking for a decent material net to net the bottles in, and triple netting the bottles to make sure none come loose and spill out polluting the water ways where I am keeping the island.

There are not many people building these floating islands in this inexpensive way and thought I would ask you guys for advise and guidance. ( apart from don't even attempt it, lol. )

I am concerned about the fishing net I am using the hold the bottles together. I would like some material with a long underwater life, there will be no U.V light on the fishing net thank goodness, but I am looking for a good strong type net to use.

It will start from a single one hexagon centre net bag 3' diameter, with a ring of six hexagon net bags surrounding the centre net bag. Then a ring of 12 net bags surrounding that, and then a ring of 18 net bags surround that, and so on...

I will use string fishing line to stitch the net bags together and use encapsulated resin coated bamboo to also hold and reinforce the net bags together.

I will top with an resin encapsulated plywood deck and then cover with earth and sand to establish and grow mangrove trees and reeds and plants balanced out over and on top of the encapsulated decking.

If anyone would like to discuss this project here and may have any useful advice for my project then please feel free to contribute your comments and ideas.

I'm sure I am not the only one thinking about doing this project, but even if you may not want to build your own I would greatly appreciate any advice or constructive comments.

Even just to talk to some people about it would be a great help, so feel free.

Thank you.

 

Welcome to the forum,

the low cost materials that make up packaging, including plastic bottle, are not chemically stable over the long run. I know there has a been a lot of false information about plastics spread as "common knowledge" about how long they stay in the environment (most of it wrong), but after only a few years they start breaking down and eventually decompose back to their original chemical components.

There are stable plastics used in a lot applications, but those cost more, and are not used in packaging. It might be possible, and in fact preferable, to reformulate the plastic bottles by melting them and adding the stabilizing components (perhaps also from recycled sources), and than mold them into sheets, hollow pipe or forms, or grating, that would make a better, stronger and more durable float platform.

wood, if protected from rot, actually holds up better that packageing plastic, and costs less. But it seems to me putting a wood deck under soil, that will be growing plants, means it would eventually rot away, even if encased in resin. You can use pressure treated plywood, it costs more, but you would not need the resin on it. You need to make sure there are under drains to prevent trapped moisture under the soil, a shallow water table is not good for the plants either (it will rot the roots). There are also durable fiberglass grate decking that is designed for outdoor use, that would make a very durable deck, that would not be harmed by moisture or contact with soil, it is not inexpensive, but it will last for many decades in your application.

perhaps using those large plastic barrels that chemicals come in might be a more durable and stable to use as floats, and than putting a grid of pressure treated lumber over it, a deck and than a thin layer of concrete reinforced with either polyester fabric mesh or a wire mesh. Seal the top with a membrane and than load it up with soil.

Here is really the bottom line: you make an island out of anything that floats, but if you want to last more than a few years it will take suitable materials that or durable. Your island will just become another trash heap as it starts to break down and fall appart in a few years, and take constant replacement of the short lived materials you are considering doing. All of that hard work would be wasted unless you use materials that will hold up to the intended use. packaging was intended to be used for a very short time, so was not intended to hold up for more than a few months, or a few years at best.

good luck.

 

Thank you Petros,

I had a thought today about changing the floatation from bottles to pipes surprisingly.

May I ask your thoughts on P.V.C pipe, I know it's quite a heavy pipe, or even polyurethane pipe?

I remember learning to heat with a hot torch or electric heat gun and crimp the ends to seal the pipe ends. Maybe that would be a better replacement for the PET bottles.

Yes, if there is misinformation about the longevity on these bottles it would be a waste of energy and I don't want to pull the island out after a few years and replace the floatation.

I will be in India so finding the right chemical stable building materials will be important.

Would you be able to show me to a link confirming the early breakdown of the PET bottle by any chance, I would like to read it myself too.

With the decking I will drill holes for drainage and for the roots of the mangroves to enter into the water, I would epoxy both sides of the plywood and inside the hole as well, but I will take onboard and study your suggestion about the replacement decking.

Yes, I would like these islands to last 30 years if possible.

Thank you for the advice Petros, it is greatly appreciated.

Many thanks.

 

Petros has done a great job explaining the limitations of junk construction. The upside is that you can easily rebuild another one in short order, but that would mean moving all your infrastructure to a new place, and getting rid of the old junk.

Your project is a really interesting topic. I have sometimes thought that the ideal material for an 'island' is reinforced concrete, like building a ferro concrete boat.

There are a few threads on the subject that brought up interesting options over the last few years.

One was to use the rubbish like bottles etc, as cheap formwork to build a concrete hull with weight saving 'bubbles' as part of the construction.

 

much of our household trash is various plastic bottles so I have often thought of acceptable usese for them. It actually would not be that difficult to melt them down in a barrell over a fire, and than mold them into something more useful.

many cities pay extra to separate their plastic container trash, and over 90 percent ends up in a land fill any way (only the "1" bottles are easy to recycle, the rest end up in the land fill). I thought it would be an interesting business to have say the city of Seattle pay extra for me to take their unrecyceld plastic bottles so I can used them. Than I reform them into plastic sea kayaks of various colors (adding what ever stabilizing ingredients to make the mix stronger), and than sell those kayaks back to those people in Seattle at inflated prices since it is a "green" recycled product. This way they can atone for their guilt for being born, feel good about paying a high price for a plastic sea kayak that will now hang in their garage or basement instead of going to the land fill, and I make money at both ends of this transaction. I figure it is "win-win" for everyone.

It seems to me that if you can use the plastic bottles to form up large reinforced pipe or a tub, adding the necessary admixtures to make it more durable, than you can build yourself a more durable floating island using recycled materials. I can imagine a giant waffle shaped structure, perhaps with epoxy coated steel rebars in the pattern, to form air chambers with high strength. you would need to make mold perhaps in the ground, leaving a layer of fine sand stuck to the outside would hide the plastic matrix.

You would have to research what is in the more durable plastics to see if this is even possible. Yes, ABS and PVC pipe are designed to be stable and durable for a long useful life, particularly if they will be kept out of the sunlight.

 

Yes, I am now thinking a waffle design of PVC pipes under the hexagon deck.

I have to work out the floatation/weight proportions, which will decide whether to use 8", 10" or 15" PVC piping.

I can heat seal the ends with a blow torch.

I can maybe even use 15" diameter pipe in the middle centre of the island and taper down to 8" at the perimeter, giving a shallow slope from the centre of the island to the outside edge allowing for water to drain away.

Thank you guys for the comments and advice, it certainly does help.

I will carry on with research into the design.

I've made friends with Richart Sowa on Facebook but I don't want to be negative about his design, he done well to make it in the first place. But your right, there are better long lasting designs to be found for longevity and safety, even if it does cost more.

Thank you.

 

I may even use a concentric rings design instead of a waffle design, as the criss cross pattern would make me have to cut and seal small sections in between the long pipe beams. Although I could just use parallel pipes and not waffle. It all depends on the weight/floatation mathematics.

If I used rings I could heat and bend the pipe to 120 degrees to form the perimeter ring to the hexagon shape.

 

PVC pipes are about the most expensive way to build a non structurally sound vessel

 

Seems to me you would want something that lasts as long as possible, considering cost, effort, safety, etc. Probably means reinforced concrete with some kind of non-rusting rebar because of permeability. Stress structural failure due to fatigue from the constant water oscillations might be a consideration with some materials and fastners. Flex life of structural plastics depends on the type, but might be a consideration. My 25 year warranty PTW landscape timbers only lasted 15 years in contact with soil, don't know if marine plywood would be similar. The company that made them for warranty is long gone- also not even taking into account the cost and trouble of removal, hauling, reassembly, etc.

Petros, maybe those recycled plastics can be used for sheeting- landscape cover, trash bags, greenhouse structures/panels, etc.? In the past there was talk about a catalyst that could be added upon remelting to decompose plastics after a few years if you wanted to go that route. Seems simpler and perhaps more profitable than kayaks, though less visible.

My favorite recycling story is with the rubber of discarded tires being powdered and mixed in with asphalt for paving roads. At one time they were considering a process using liquid nitrogen to quickly strip an shatter the rubber part, but I don't know what actually came of that...

PC

 

If there is concern about the durability of PET that you cannot get around why not adopt a hybrid strategy where your core residential component(s) are supported by ferrocement raft(s) and your supplemental or connective garden/yard are sections supported by plastic? This approach removes uncertainty with respect to the bits that matter most.

 

There's a construction product called bubbledeck, which uses plastic spheres held in the rebar grid to form voids in a concrete slab. I wonder if it would be feasible to do a similar thing with large plastic drinks bottles? How closely could you pack them? use a grc matrix or similar? They wouldn't have the bi-dirctional qualities of the sphere- what packing pattern would you need? Could you ever get to the point that the composite slab was a buoyant raft?... (you could of course adopt the principle to form a hull)

 

TT:
Interesting, thanks for the pics!

Concrete is strongest in compression mode, and not as good in shear or twist mode, as I understand it. So the bubble structure which works well with compression modes for floors, might have to be reinforced with more concrete and rebar (especially at the center area) to hold together when the stress of water oscillations is considered? The concrete beams used for bridge construction might give a clue as to what is required for shear (no bubbles), but I notice some bridges still must use steel I beams at certain areas like curves (for twist loads?). Seems to me that the plastic drink bottles would have to be identical in order for the easy and uniform matrix pattern to have a predictable strength in a design purpose. Probably would be quite heavy even with the plastic spheres pictured in the thickness required to handle the load and stresses. So my thinking is a "hull shape barge" with at least a partial plastic superstructure then soil to prevent swamping. Since there would be inhabitants aboard the safety issue is quite prominent. Even anchored offshore oil rigs have potential for damage and collapse during storms which have caused loss of life. Evacuation can rapidly become problematic, even with the last resort survival capsules...

FWIW as I am not a structural engineer...


OE

 

Thank you for your current input, it's greatly appreciated.

It's a fascinating subject as I really want to get my island built in the next few years.

I hope it may help other people interested in the subject, so all ideas and techniques can be discussed here rather than talking about one project.

Something's work better than others, and there is a big weight difference between the two deferent designs. It's great to hear all the ideas and comments.

So thank you again.

 

Intersecting construction technique.

One thing about ferrocement construction is that it is thin wall construction with a lot more steel per volume that that. Like a plastered wall rather than poured slab.

 

My 2 cents:
I love the idea but I would suggest concrete blocks that have a polystyrene core, similar to what our yacht club jetties are made of. I have seen similar blocks in Durban and they have stood up to many years at sea conditions.
Your main platform should be a reliable construction and these interlocked blocks could be made to "flex" with wave action, with a hinged arm assembly.
The plastic bottles that go rotten eventually is great for planting trees and beaches, they have to be replenished regularly but your main construction will be permanent.
Our harbour has got blocks that are 20 years old and nothing wrong