Projects: Creating the unconventional with epoxy resin infusion

Danish shipwright Jørgen Jensen prides himself on building boats that push boundaries and when he was commissioned to build the innovative Pi Boat entirely from carbon fibre, he knew PRO-SET® infusion epoxy had a central part to play.

As an increasing number of tourists in the Danish capital Copenhagen will tell you, Pi Boat is not a conventional craft. Long, light and thin but with a distinctive, almost square cockpit, it currently sits in the city’s harbour, a short distance from the iconic Little Mermaid statue. As boat builder Jørgen Jensen says, Pi has become a tourist attraction in its own right.

“Michael Larsen, who commissioned the boat, lived in it in the harbour for a while to test it out – everyday people would come and ask about it,” Jørgen says. “Lots of people would come to see the mermaid but then take a look at the boat and step on board without asking. It’s good that people notice it, but at the same time it wasn’t easy for Michael!”

The partnership between Michael and Jørgen was born during a Christmas dinner party. The pair started talking about boats and quickly realised they shared the same desire to do things differently. By the end of the evening, Michael had arranged to meet Jørgen to start planning a boat that ‘promoted the joy of sailing and created a sailing class all of its own’.

The decision was quickly made to create the craft from carbon fibre and at that point Jørgen’s mind turned immediately to epoxy resin. “I’m a big fan of PRO-SET epoxy,” he says, “and I have been since I built my first carbon boat 25 years ago. I like to take things a step into the future, instead of just using polyester. I like to challenge things and move forward.”

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An appetite for innovation

Jørgen is a fourth-generation boat builder, following on from his father, grandfather and great-grandfather. He worked on his first boat aged ten and left school five years later to work as a shipbuilding apprentice.

“My family has always done crazy stuff with boats,” he says. “We find boats in ruins and make them new. We buy fibreglass hulls and change them into something else. It’s what I’ve always done.”

For Pi, Michael’s vision was for a mid-sized vessel that combined comfort and speed, making it suitable for both cruising and racing – without either aspect being compromised. He wanted a design based on a very stable, almost boxy profile with as little surface in the water as possible and he wanted to be able to live on the boat, so the craft needed to be spacious. It was a project Jørgen was very happy to take on.

Epoxy infusion: straightforward process, exquisite laminate qualities

The Pi team chose to build using carbon fibre because of the strength it offers at a reduced weight and because of the stiffness and speed it can provide without compromising comfort. Although Jørgen had built carbon boats before, this was the first he had worked on using vacuum infusion techniques.

In vacuum infusion, core materials are laid out dry into a mould and the vacuum is applied before epoxy resin is introduced. Once a vacuum is achieved – creating firm, evenly distributed pressure – epoxy is sucked into the laminate using a network of transport mesh, channelled core, pipes and manifolds.

This process has a number of advantages. It generates a superior bond with fewer air voids, resulting in a stronger composite and because excess epoxy is extracted from the laminate, the process creates an optimum fibre-to-resin ratio – reducing weight and waste.

For Jørgen and Michael – who decided early on in the project to become involved full-time – vacuum infusion was a revelation.

“Thanks to the support we received from our PRO-SET epoxy distributor, HF Industri & Marine, everything went smoothly,” says Jørgen. “Essentially, once we had built the mould, there were three steps. We applied the first skin, then left that to fully cure, then applied the core materials – which we heated on the first skin so we could bend them accurately – and after applied the outside skin.”

“It took about a month to build the mould, and the whole process of creating and laminating the keel took around three months in total.”

“There are a lot of advantages to working this way,” he adds. “It’s a much cleaner operation which will save you time and yet create an extremely strong bond. It creates an exceptionally solid composite and you know it’s in the shape you really want it to be in. This gives you the confidence that you’re creating a product you can trust.”

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“We used epoxy for everything.”

With the 45ft hull created, the containers of PRO-SET epoxy remained close at hand, as epoxy resin and hardener was used throughout the job.

“We used epoxy for everything,” Jørgen says. “For the bulkheads, for reinforcement around the keel, for laminating the superstructure to the keel and so on.

“We had the idea that we wanted to do everything in carbon fibre so, for example, the lifting keel is just carbon and because Michael wanted as few moving parts as possible, it’s just carbon against carbon with no bearings.”

Ultimately, the team fell slightly short of building absolutely everything in carbon (“We wanted to go out sailing and using so much carbon takes time,” Jørgen laughs, explaining why the forestay and some rigging extensions ended up being made from stainless steel).

But the boat that launched in 2014 otherwise remained entirely true to Michael Larsen’s singular vision. It is, Jørgen says, “a fantastic boat to sail and a great boat to socialise on”. He also admits that Pi is proving a difficult project to follow.

“Unfortunately I now have to go back to normal boat building work,” he smiles, “and it can seem a little bit slow after Pi. It is difficult to move on. I’m really hoping someone orders another one!”