Plastic Fantastic

This story begins with a lost dog, and ends up in deep water. In between, there is collaboration between a diver with an idea for a better swim fin, the designers who brought his idea to life and materials suppliers who found the right resin blends to make it all work.

And there is also a bronze-level honor in the International Design Excellence Awards for the product they brought to the market: Omega Aquatics’ Amphibian swim fin with a blade that moves out of the way to make life easier for divers before they even enter the water. (The IDEAs are annual honors from the Industrial Designers Society of America.)

Fin creator Ronen Moyal, an avid diver, came up with a concept for a swim fin in which the blade would pop up and away from the foot bed.

The idea was to make it easier for divers to walk on the beach or a boat deck with the fins on, while getting ready to enter the water. But though he had gotten as far as putting his concept into computer-aided-design files, he did not know where to go next.

Enter the lost dog.

One afternoon, one of the workers at Designcraft Inc’s offices in Lake Zurich, Illinois, found a dog wandering in the business park, took it in and started looking for the owner.

The dog belonged to Moyal’s wife, who had another business in the park, and who mentioned that her husband had an idea for a new product, said designer Casey Stahl in a 13 September interview at the IDSA´s annual conference in Phoenix.

The diver and the designers hooked up, and Designcraft quickly saw the potential of Moyal’s concept.

“He’d been kicking the idea for a while, and when we saw it, it was almost one of those, ‘Why didn’t we think of this?’ projects,” Stahl said.

Walking with fins is awkward. Putting them on when the diver is already loaded down with scuba tanks and a weight belt can be dangerous, he said. Pulling them on in the water wastes time.

The Amphibian is designed so the diver can put them on right away, move comfortably on land, and swim away quickly once he enters the water, with the flexible motion of the fin itself pushing the blade into place.

Through the two-year development, the companies faced two major issues, Stahl said - which materials to use, and the mechanics of getting the fin to flip up out of the way when on land, but pop into use easily in the water.

Material choices were limited, as the fin and its movable parts needed to be able to stand up to salt water and the cold of a subarctic dive, but also move easily in the water.

The final product relies on two small stainless-steel springs on either side of the fin, and a polypropylene hinge molded into the PP substrate structure. The PP hinge also can be pushed down to release the blade with the heel of the other foot, which makes it easier to move the blade out of the way and climb a boat ladder at the end of a swim.

GLS Corp of McHenry, Illinois, was brought in to provide the right thermoplastic elastomer to add flexibility to the structure, with the companies taking advantage of the chemical bond of a TPE overmoulding on the PP substrate.

“It needs to be both flexible and robust,” Stahl said.

The fin uses two blends of GLS’ Dynaflex TPE to tweak the flexibility where it’s needed to give the fin the best possible performance in the water, said Dyana Hunsaker, GLS sales representative. The Amphibian also uses GLS TPE on the sole of the foot bed, to give more secure footing on slippery surfaces.

“Initially we called in GLS to help us on the bonding issue, but they helped us troubleshoot when we were running into problems in processing,” Stahl said. “We were able to find where we’d designed the PP a little too thin for what we needed in moulding.”

The Amphibian hit the market in late 2007, and Omega and its partners are working on future projects now, including a military-grade version, he said.

* Rhoda Miel is a journalist at Plastics News, a sister title of PRW and EPN