Poseidon’s Trident Hybrid Cage System making waves

October 2019, Poseidon Ocean Systems delivered the first Trident Hybrid steel cage system to Cermaq Canada on the west coast of Vancouver Island. At first glance, the 40m x 40m square cages look a lot like other steel cage systems that dot the rugged coastlines of Canada, Chile and Scotland. But if you look closer, you’ll see the similarities are only skin deep.

Open nets, or closed containment?
Imagine if you could switch from traditional net pen farming to floating closed containment as easily as you change nets. Marine engineer and co-founder of Poseidon Ocean Systems, Matt Clarke, said that with Trident, you can.

“Trident is a generational leap in fish farm structural design,” he said. “Aquaculture has come so far in such a short time and we felt that cage system design needed to evolve with the industry.”

Trident’s cage technology has been in development since 2017 by a team of engineers focused on the aquaculture industry. Clarke explained the new design is still completely compatible with existing farming practices, with costs comparable to conventional designs. “We set out to raise the bar for aquaculture and we’re very proud of what we’ve accomplished.”

Setting the standards
If you’re going to design aquaculture equipment, there are two standards to follow and Poseidon knew where to find them.

“We’d been working with the Norwegian Standard NS:9415 for years and it sets a very high bar,” said Clarke. “We also work with the Scottish Standard and the two standards are aligned on cage design. We know that cage system failures and fish escapes have a negative impact on the global industry, not just the operators directly affected. By designing to the standards, we’re lowering the risk for the entire industry.”

Strength and durability by design
To meet the rigorous design standards, Poseidon completely re-imagined the steel structure itself. “We put a lot of effort into the structural design and ran hundreds of simulations to make sure it will stand up in high energy environments. The result is a steel cage structure that is 50 to 100 percent stronger than existing designs and is more suitable for deployment at higher energy sites than anything that has come before us.” Clarke explained that Trident has been designed to handle maximum wave heights of more than six meters.

One look at the hinge design on Trident and you can see what he’s referring to. “The hinges are the most critical aspect of steel cage system design, so we went above and beyond on those components to make sure that the system will last.” He explained that the manufacturing tolerances and material quality are unmatched in the industry today. “Our pins are 50-mm diameter high strength steel, paired with PTFE composite bushings. We expect that most customers won’t need to replace our pins or bushings, ever. The result is a 20-year design service life for the structural components.”

Hybrid structure
“The flotation on Trident is HDPE pipe, the same as we use on circular cage systems. It is much stronger and more durable than conventional billets. As a result, we guarantee the flotation for the life of the cage,” said Clarke.

He goes on: “It isn’t just about better flotation, it’s also about how we use the flotation in Trident. The system is a hybrid design; it is a combination of the best features of steel cage designs, combined with many of the best features of circular cage designs. The pipe is an integrated structural component that is continuous throughout the entire farm. There are no gaps at the hinges or unsupported spans like you have with conventional billets. That translates into vastly improved buoyancy, strength and dynamics. This is really apparent during storms – the Trident system responds to waves with a very calm and subdued motion, almost like a giant shock absorber. The typical heaving and lurching motion of conventional cages is nearly eliminated. It is hard to capture in words just how dramatic the improvements are.”

Closed containment capable
“The advancements we’ve made in the structural design with Trident are so profound that it makes floating closed containment an economically viable option for farmers.” The strength and the stability of the new design makes it capable of supporting existing floating closed containment technologies, Clarke said. “From the structural advancements, to the flotation and right down to the load distribution system, Trident is ready for closed containment operations right out of the box.”

“We see this is a game-changing capability for our customers going forward. Trident as a closed containment structure is a fraction of the cost of conventional closed containment designs. It allows farmers to integrate floating closed containment much more easily into their existing operations to create hybrid farming models,” said Clarke.

“One scenario for these hybrid operations is to use floating closed containment systems for the juvenile stage of the grow-out period. By raising smolts from 100 grams to around 1.5 kilograms in floating closed containment, farmers can double their production output for a fraction of the cost of expanding a hatchery or even their net-pen operations.”

Integration is key
With Trident, Poseidon looked to integrate modern farming equipment right into the cage. “We’ve been focused on integration since day one,” said Clarke. “When you look at fish farms today, they have more and more equipment on the cages, some of which didn’t exist just 10 years ago and farmers have nowhere to safely put everything. A core design goal was coming up with a solution that would allow us to recess all equipment under the decks, but still make it easily accessible for installation and maintenance. This gives farmers properly integrated systems within the farm itself while improving worker safety and reducing maintenance requirements on all equipment.”

The Trident system uses durable fiberglass reinforced plastic decking that allows farmers to run their feed lines and everything else they need on a modern farm safely under their feet. The removable panels are easily replaced in the event of accidental damage.

“That’s one thing we saw repeatedly with welded steel decks – once you damage those decks, they’re very difficult to repair, so the farmer is often stuck with the damage for the life of the cage. With Trident you can replace a damaged deck panel in seconds and safely get back to work.”

Cermaq’s perspective
Cermaq, one of the world’s premier aquaculture companies, had this to say about the Trident Hybrid Cage System: “For us, the biggest benefits we are realizing from the Trident system is the overall improved stability and safety of the structure. The cages have exceeded our expectations for performance during storms, and the feedback from our employees working on the system has been positive,” said David Kiemele, managing director for Cermaq Canada.

“General safety is improved as the system allows for storage under walkways, reducing piping, ropes and cables on the surface of the walkway, which has reduced tripping hazards. We are happy with the security the system provides for our fish, as it is able to shift and flex with all wave and weather conditions.”

The future is now
With so much promise, what does Clarke see as the next challenge for the patent-pending Trident Hybrid technology? “We’re eager to work closely with customers who are interested in seeing how Trident can transform their farming operations. We believe that innovative customers will be able to use Trident to take a big step into the future for aquaculture. We’re excited to be a part of that transformation going forward.”