Pisces III being recovered from 1575 feet/ 480m after a near fatal mishap in 1973
The Submersible (Human Occupied Vehicle) industry has a long standing reputation for impeccable safety records, but this reputation was marred by the completely avoidable OceanGate tragedy.
This excellent safety record owes much to the industry’s adherence to the rules and regulations outlined by the classification bodies listed below *. For those unfamiliar with the story of Roger Chapman and Roger Mallinson’s harrowing experience, it is documented in the book “No Time On Our Side.”; this event was the basis for many of the rules and regulations in place today. It is commonly referred to as the deepest manned sub rescue ever at 1575 feet, however it is not. There was another successful sub rescue at just over 1800 feet deep in the Gulf of Mexico in 2002, where a work class ROV intervened and freed the pilot within about 15 minutes after arriving on site.
(*not a complete listing)
In addition to providing rules for sub design, construction and operation, these entities perform regular surveys to ensure submersibles remain in safe operating condition. Without a current class certificate, the sub is not able to get insurance nor legally continue to operate.
Submersibles, like life rafts or lifeboats, must carry essential supplies like food/water/emergency equipment to sustain a full crew for the planned dive duration, plus 96 hours. If a rescue is ever required, this time frame is the critical factor which dictates everything from equipment onboard, crew training, and emergency procedures.
Some operators choose well-known, hazard free dive sites within safe scuba diving limits, like Atlantis Submarines, which has safely conducted tourist subs dives worldwide for over 25 years.
Adherence to safe diving limits includes monitoring underwater visibility, maximum depth, maximum current and wind speeds, surface weather conditions and keeping clear of high traffic areas. Using a small tender as a surface vehicle may not effectively clear the area of traffic, making diving from the mothership the safest option.
Recent incidents, like the one in Antarctica where a tourist sub became entangled in shifting surface ice, underscore the importance of maintaining situational awareness. Having the mother ship conduct the dive helps ensure maximum situational awareness and readiness for a prompt recovery if needed. Operational procedures like this would have likely prevented that specific incident. No injuries were reported, however serious damage to the sub occurred.
On the surface, provisions for towing and recovery of the sub must be in place and your tender must be able to effectively tow the sub back to the mothership in all conditions.
The mothership should be nearby for a swift recovery especially in emergencies, and we recommend dive operations from the mothership. A Dynamic Positioning (DP) vessel is not mandatory, but highly recommended, as it keeps the captain and bridge crew involved, and quickly gives the sub crew extra support if necessary. This also minimizes boat traffic around the dive site, and provides extra attention on weather conditions.
Like with most workplace mishaps, a well thought out risk assessments and prevention effort is the most effective method of avoiding incidents. Safety plans for a disabled sub underwater involve maintaining communication and knowing the subs location. Communication logs are updated every 15 minutes , and specific recovery steps are outlined in case of communication or tracking failure. Swift re-establishment allows the dive to continue; otherwise emergency protocols must be initiated both underwater and on the surface.
Entanglement prevention on new dive sites can include a site survey by ROV, AUV, or sonar prior to any diving. Proper sonar equipment and crew sonar training is essential.
Image not from the ice incident, rather to show the reliance on surface support necessary
*Navigating around ice can be difficult from small boats and subs due to visibility close to the water line.
In addition to prevention efforts, having a self-help or outside rescue plan is essential. Self-help plans may involve a second submersible diving in tandem, providing assistance in case of disability
Aside from added safety, one of the best things to see from a sub is a second sub.
The dives to Titanic in the 1990’s from the Russian MIR subs and the R/V Akademic Keldysh (in partnership with Deep Ocean Expeditions) was a prime example of this tandem dive operation. Check out “Ghosts Of The Abyss”, “Aliens Of The Deep”, or the classic movie “Titanic” with this in mind and you will see how incredible a dual sub dive is.
Tandem Triton 3k3 dive @OceanX
Another self rescue option would be for the submersible operator to carry its own capable ROV onboard. This should go without saying, but the ROV must be maintained well, the crew trained well and regular drills must be conducted. If these three things are not in place it is worse than not having one as it will lure everyone into a false sense of security. If you can not get your ROV to the sub and effect a rescue, then all you are doing is delaying a proper rescue vehicle from mobilizing. The clock keeps ticking on that 96 hour window.
Outside rescue plans contract vessels with capable ROVs on standby, crewed and dive ready for the duration of the contract, although this can be costly for sub operators.
All ROVs are not created equal
Available ROVs can range from depth ratings of 30 metres to 6000m, and vary in power from 350 watts to more than 120 Kilowatts of power. These obviously vary significantly in capability, and carry tools from simple grippers to powerful 7 function hydraulic manipulators. Choosing the right ROV for depths of 500m or more is crucial; micro systems are not suitable for this task, mainly due to their lack of ability to get to depth. Battery powered ROVs are completely unsuitable for sub rescue applications.
The ROV can also serve additional functions, such as scientific exploration, and can enhance the experience for guests who can’t participate in submersible or scuba dives. It allows them to connect with the underwater world, making it an excellent option for people with claustrophobia or physical limitations. The live stream should be displayed on the bridge, but can also be viewed in personal cabins, or in the onboard theatre on larger vessels.
Whether you are looking to conduct subsea science and film work, or simply enjoy submersible exploration, planning the integration and accessory package should be a priority before purchasing any submersible Space constraints and delivery times are always a considerations, but they should not be the main drivers in choosing a rescue system; The ability to effectively rescue a disabled sub in a timely manner must be the prime factor.
The Indepth Group can assist you in meeting your operational goals.
Contact us in the early stages of project planning for best results.
