Imagine collecting thousands of empty plastic bottles, lashing them together to make a boat and sailing the thing from California to Australia, a journey of 11,000 miles (17,700 km) through treacherous seas.
You'd have to be crazy, or trying to make a point. David de Rothschild is trying to make a point.
De Rothschild hopes his one-of-a-kind vessel, now being built on a San Francisco pier, will boost recycling of plastic bottles, which he says are a symbol of global waste. Except for the masts, which are metal, everything on the 60-foot catamaran is made from recycled plastic.
"It's all sail power," he said. "The idea is to put no kind of pollution back into the atmosphere, or into our oceans for that matter, so everything on the boat will be composted. Everything will be recycled. Even the vessel is going to end up being recycled when we finish."
You have been on the ocean for 54 days now. How is it going?
Really well. I have to keep pinching myself that we are floating on a boat made out of 12,500 2-litre reclaimed plastic bottles.
Why is your boat, the Plastiki, built out of these bottles?
We thought they would make a tough hull but we also wanted to highlight the bottle's status as one of the most disposable plastic items we buy. This project is about taking a symbol of dumb plastic 1.0 - the single-use, throwaway kind - and making it functional. The Plastiki gets 68 per cent of her buoyancy from the bottles.
Environmentalists' knee-jerk reaction is often to vilify plastics. Instead we need to differentiate between the throwaway kind - the bottle, the bag, the polystyrene foam - and the smarter materials like the laptop I'm using now or the lifesaving machinery in hospitals. The latter have a valued place in our society and a longer life cycle but we need to re-engineer them to have a closed-loop life cycle, so that they are recycled over and over.
Is this kind of smarter plastic incorporated into the design too?
Yes. The structure of the boat is made out of a material called self-reinforced polyethylene terephthalate (srPET). It is a single-substance material which means it is easily recycled.
What is srPET used for today?
Not much. It has been around since the 1980s but there hasn't been the desire to take it out of the laboratory. It is slightly more expensive than less green alternatives, but I think the market is starting to move on. People want to know where their materials come from and how they affect the health of the planet.
Did you offset the carbon footprint of manufacturing the boat?
Our footprint was a lot smaller than it could have been because we manufactured a lot of the boat ourselves off-grid, using solar power. When we got into tracing the carbon footprint of all the stuff we had ordered, it actually became financially restrictive for us to do the analysis. We got a quote from one company that was of the order of $100,000 to do a full analysis of our carbon footprint.
A lot of firms brand themselves carbon neutral but they don't say when their neutrality began - you have to go all the way down the supply chain.
Have you seen more plastic than fish in the water during your time at sea?
Yes, by a long way. The issue is far more ominous than people imagine, as the Pacific garbage patches are not just floating islands of trash. They are mainly subsurface - tiny pieces of material in the process of breaking down and floating in the top layer of the ocean where most species live and breed. When we look underneath the boat, the hull is covered in a fine, extra layer of plastic. It is tragic. From above, the oceans still look beautiful and untouched but just below the surface is this toxic stew that could quickly end up on our dinner plates.