I had a really interesting chat with Jo Royle last week. Jo, 30, from Lancashire, is the vivacious and knowledgeable skipper of Plastiki, the eco-yacht currently sailing across the Pacific.

Plastiki is midway between the island of Kitimati, or Christmas Island, and Fiji, and her crew, including co-skipper David Thomson (brother of solo sailor Alex) were trying to coax the 60ft catamaran along. This is by no means a fast boat and they said they were doing well to get 5.5 knots from her – downwind.

If you’ve read about Plastiki you’ll know that she is built from around 12,000 two-litre plastic water bottles. They were bound together in a retaining net and fitted over a frame made of Seretex, or srPET, a recyclable material developed from the team. Each bottle in the hull is filled with 12 grams of dry ice to make them stronger.

“Plastiki is a bit slow,” Jo confesses. “About 70 per cent of her buoyancy comes from 2lt PET bottles so there’s quite a lot of drag, though we do have quite lot of sail area in our ketch rig.”

There’s another thing. Because no-one was entirely sure how strong and rigid the boat would be when she was being built there isn’t a bow bar and therefore no central position for a headsail. So Plastiki has two headstays, one from each hull.

“It’s challenging to sail upwind because the headsail has to be sheeted from the leeward hull and so we can’t tack and we’re limited in the angle we can sail,” says Jo. “We sail mainly between 100° and 150°.

“Normally you talk about a boat’s no-go zone. Well, we have a ‘go zone’ of about 40°. Navigation is definitely interesting.”

Nevertheless, Plastiki wasn’t built for speed but to demonstrate the uses of recycled material, or material that could be ‘upcycled’ – in other words converted afterwards to new material or products of the same or better quality or higher environmental value.

And in this sense, she is a great way of raising the profile of recycling and drawing attention to the huge amount of plastic waste that needlessly ends up swilling around the oceans.

Plastiki is also a fantastic example and case study of our – yachtsmen’s – wastefulness at sea: our over-reliance on diesel and blinkered thinking when it comes to power on board.

So far, Plastiki has used not a drop of fossil fuel. The crew routinely use electronic charts, run AIS, make and edit film on board every day and are in contact ashore a lot; we spoke on their INMARSAT Fleet system. This is all powered by wind or sun.

They have a trailing water turbine as well, but so far have not had to use it.

The Plastiki crew is reviving previously well-used but now almost obsolete ocean techniques, such as collecting rainwater. Rather than expensively running a watermaker, a gutter running round Plastiki’s geodesic coachroof collects rainwater.

During a typical tropical storm there can be plenty. The day before we spoke the crew had collected 400 litres. They stopper the gutters for the first few minutes to avoid contamination from encrusted salt, but after that the water is pure and needs no treatment.

Plastiki is, Jo explains, exactly like an off-the-grid house. “Everything is very raw and basic, but very safe and comfortable,” says Jo. “And this is the first trip I’ve done where I haven’t spend hours in the engine room or repairing electrics.”

We’ll have more about Plastiki, and the fascinating story of her ecological ingenuity, in one of the next issues.