The Triton 3300/3 submersible

Interview - John Ramsay CTO Triton Submarines

CTO of Triton Submarines John Ramsay is a product design engineer who has spent his career perfecting a new generation of small submersible vessels for subsea filmmaking, leisure and treasure hunting.

For most engineers of a certain age, the idea of a small utility submarine will conjure up images of Gerry Anderson’s wedge-shaped Thunderbird 4. This canary-yellow classic would emerge dramatically from the ‘pod’ of the mothership transporter Thunderbird 2, ready to explore the ocean depths. While expeditions in manned submersible craft have been the stuff of science fiction since Jules Verne’s Captain Nemo travelled 20,000 leagues under the sea in the 19th century, the appearance of real miniature submarines for use in the civilian context is comparatively recent. As John Ramsay of Triton Submarines says, they are pushing back the final frontier of Earth-bound human endeavour.

In 2013, the first remarkable video footage of a giant squid was captured from a Triton 3300/3 submersible, while earlier this year David Attenborough was seen on our TV screens exploring the Great Barrier Reef for his BBC documentary series of the same name, using the same technology. The age of the personal submarine has not only become a reality, but is opening up a new world. It’s not much of an exaggeration to say that while we know pretty much everything there is to know about the surface of the Moon, there are species of marine life at the end of the local pier that have yet to be recorded.

Ramsay, the chief technology officer of Florida-based Triton, recalls how the founders of the company, Bruce Jones and Patrick Lahey, would turn up to boat shows 25 years ago and were “laughed at when they said they could put a submarine on your yacht.” The market, he says, has steadily grown as yachts have become bigger and better, while their owners “want more diverse experiences. We’ve been right in that market from the very beginning.”

There is a distinct portfolio of clients for the vehicles, which range in cost from £1.5m to £3m. First, there are owners of luxury superyachts keen to display their wealth, as well as subsea treasure-hunters eager to acquire it. Then there are explorers, scientists and filmmakers pushing back the ocean’s frontiers, followed by less glamorous operations such as surveying and subsea rescue. “But you need a person or organisation with the financial resources. It seems to be the private sector rather than national institutions that show the most interest. After that, it all depends what they’re going to be used for. We’ve done a lot of filming, with Attenborough’s ‘Great Barrier Reef’ being the highlight.”

One of the leading lights in his field, 35-year-old Ramsay has been designing personal submersibles since he left university in 2002. He endured, rather than enjoyed his degree in product design engineering at the Glasgow School of Art and left slightly disillusioned by the experience, his future uncertain. By pure chance he walked into “an incredible job” with a Royal Navy contractor working in submarine rescue, where the idea was to provide vehicles for getting people “out of distressed military submarines that were sitting on the seabed.”

While others were refitting and making ready-for-purpose 1970s subsea technology, Ramsay thought he’d be “sweeping floors and painting containers. But when I arrived on the first day, they said they were not 100 per cent sure they had any more summer work and introduced me to their designer, who told me to learn AutoCAD over the weekend and start on Monday. I basically owe my entire career to Ben Sharples, their designer, who gave me that opportunity.”

Some 15 years later, Ramsay finds himself head of design engineering at Triton, suppliers of units that “are used all over the world.” His job title changes throughout our conversation, as it is clearly something of little concern to him, but ‘Triton’ remains front and centre. The name of the company comes, of course, from Greek mythology, where Triton, son of Poseidon, was the messenger of the sea. The company Ramsay works for is by no means the first to have associated submarine technology with the trident-wielding merman, and is highly unlikely to be the last, but for now, the British engineer has been involved with every sub to come out of the company. Although the Triton series includes a range of vessels from a three-man 11,000m full ocean depth model (36000/3), to the smallest of the fleet (3300/1 MD), the company’s flagship model is arguably the 3300/3 that has a depth limit of 3,300ft (1000m) and a crew complement of three.

Submersible or submarine?

Although the terms submarine and submersible are – broadly speaking – interchangeable. Even Ramsay himself is not “entirely certain what the difference is”, but he prefers submersible. Yet on one thing he is quite clear: “they’re pretty simple things, really,” he says. Their most critical aspect is understandably “what goes down must come up again. That’s the first rule.” In order to do this, the submersible must weigh the equivalent to the water it displaces. “If it is going to displace eight cubic metres of water, it has to weigh eight tonnes, as is the case with the 3300/3 vehicle, with a ballast system that can put in or take out a little bit of weight from that. To make a submarine comfortable to sit in, there has to be an associated weight, which is why they are quite heavy. This always surprises yacht builders who are used to having little lightweight tenders. But you can’t beat the laws of physics.” You can’t deceive the load capacity of the lifting gear that gets submersibles in and out of the water either. The overall weight spec of your state-of-the-art miniature sub is ultimately limited by something as mundane as how big your on-board crane is.

The second parameter is stability in the horizontal plane. “These vehicles are designed to be comfortable for the user, so one of the important aspects of the design is that it has to sit upright in the water. It’s not like a military submarine that will go into a dive where it literally points downward. With ours, we want them to stay flat, whether they are being lifted, sitting on the surface with the ballast tanks full of air, or in any of its trim conditions, going up or down. That means weight must be equal and opposite to buoyancy and the centre of gravity must remain perfectly below the centre of surfaced displacement, submerged displacement, and the lift point.”

Propulsion is in the form of four electric thrusters in a ‘vector thrusting’ configuration. Two of the units point fore and aft to control backward and forward motion (including turning), while a second pair that point up at an angle of 45° from the vertical plane allow up and down movement as well as sideways ‘crabbing’ left and right. “With that you have complete control. There’s a lot of complex processing in the main computer system that takes the pilot’s input from the joystick, along with data from all the on-board sensors, and then tells which thruster to go at what speed.”

For the uninitiated, it comes as a surprise that the designer hasn’t even mentioned oxygen supply for the crew as an important design factor. The reason for this is that it is relatively straightforward – operational subsurface duration is limited more by the capacity of the human bladder than anything else. In theory, you can dive for up to 12 hours (and there’s a back-up oxygen supply of 96 hours in case anything should go wrong). Yet long before that, the call of nature will be upon the crew and, as there are no on-board facilities for that purpose (apart from a “very embarrassing” solution to comply with emergency life support requirements), surfacing will ipso facto occur well inside the limits of technical operational parameters.

Improved visibility

What is far more important for the crew is visibility and this is where Triton subs really take the laurels. “The highlight of all the vehicles is the transparent spherical acrylic pressure hull,” or bubble, which is 2.1m in diameter and is the largest acrylic sphere ever made for a manned submersible vessel. “The fun part is making it so that you’ve cut away as much of the vehicle’s structure as you can to allow the occupants the best possible visibility. What we have done on the 3300/3 is pretty much manage to get rid of the chassis at the front end, so you’ve got a completely open view from down at your feet, going forwards and right the way up to the hatch.”

This is a massive development from earlier subs, where there was a chassis crossbeam “holding the sub together that went right across the viewing area.” This was a design change that Ramsay had to push for because it wasn’t seen as “entirely necessary”, but now that he’s pushed it through, “it works pretty well”. Ramsay goes on to explain that the main bulk of the vessel’s buoyancy comes from the acrylic hull “because acrylic is not far off being neutrally buoyant. The heavy stuff comes in the form of electronic systems, batteries, HP gas cylinders and ballast tanks that you want hidden away behind you in the fairings of the main chassis of the sub.”

The problem is that “these try to pull the tail of the sub down and you need to offset that with a load of weight at the front end, which you don’t want to get in the way of the view. A lead payload put up front, hidden in the pontoons can be replaced on mounting points with tooling or camera equipment, archaeological manipulator claws, sampling science trays and so on. If you look at the vehicle, you can see that the pontoons are tapered away to give you the best view. There is still a crossbeam up front, but it is stepped right back and you can look straight down over it.”

Access to the acrylic sphere cockpit or, more correctly, the PVHO (pressure vessel for human occupancy), is via a large 550mm diameter, 170mm thick hatch from a ladder mounted on the back of the sub. “You kind of hop in,” says Ramsay. “To put it into context how easy that is, we had 90-year-old David Attenborough getting in and out of the vessel for a fortnight in Australia without any problems.”

Safety first, second and always

There’s a sentence on the Triton website related to safety that’s worth quoting in full: “when the paperwork weighs as much as the submarine, our work is done”. Surely this is an overstatement? “It’s probably not far from the truth,” says Ramsay, whoexplains that “the paperwork is relentless. Everything from the bolts that we use needs certification for chemical composition and strength and so on. Then they have to be independently tested. You buy them certified and the material itself is sent away for chemical analysis and mechanical testing. Then the whole unit is pressure tested at 1.2 times its rated depth, while being designed to go more than 1.7 times its rated depth and still survive. There are tons of different analyses and reports detailing every aspect of the vehicle. It is normal stuff in engineering terms, but it is quite intense.”

While the paperwork might be all in a day’s work for a design engineer, encountering the truly enormous 13m giant squid (only beaten in size by the aptly named colossal squid) is not. “We’ve known about them for some time. There’s actually one in the Natural History Museum that was probably taken from the surface.” However, when one was filmed from a Triton sub in 2013 off the coast of Japan “it was the first time that human eyes had seen a living one in its natural habitat.” For Ramsay this is exciting. We live in an age where we know more about the far side of the Moon than we do about what goes on in the world’s oceans. “You can go down in the water and film a new species every dive,” he says. “It is incredible that the oceans remain unexplored. The second you are underwater you’re probably going to see something that no one has ever seen before.”

This means that, for Ramsay, designer of submersibles, “it’s a privilege to be creating these things and then watching them being used. It is so satisfying when your work as an engineer performs as it is supposed to. When you go out for the sea trials, you’ll typically sit there for a whole day looking quite nervous and feeling a bit sick and anxious. But within ten minutes of the sub being launched for the first time they had it ballasted and the thing was underwater, and we could hear sounds of glee coming from the pilot over the underwater telephone. It’s a fantastic thing.”

To find out more about Triton’s submersible range and to see footage of the giant squid, as well as the BBC’s Great Barrier Reef, visit

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