Adventure Bay Charters – Bottom Cage Dive Safety Procedure
Bottom Cage Dive Safety – 18 metres down
As a responsible wildlife tour and dive tour operator, safety is our number one priority. This page will provide background and knowledge about our safety procedures and an overview of how the bottom cage dive operates. There are two roles from our staff on the day of the tour, these include a dive supervisor and the cage captain.
The Dive Supervisor remains on the vessel monitoring the dive, from the first safety briefing to the end of the last dive. They must be qualified in all aspects of the cage operation. Their role is to monitor and instruct the Cage Captain. They are responsible for everyone’s safety in the cage, ensuring triple dive safety and a proper dive briefing are covered pre dive. They must double check the pre dive safety checks, monitor and record these on the dive log sheets. They monitor and communicate with the Cage Captain throughout the underwater pre dive safety checks, customer mask and ear tests – ensuring that the conditions are safe and that all all the staff members are aware that a bottom cage is underway. They monitor closely the air supply during the decent down, communicating with the cage captain through the comms system about the conditions and the customers wellbeing. The Dive Supervisor is responsible for the length of the dive, including the early termination if conditions change. On the return to the surface they will hold the cage at 5 meters for 3 minutes pre agreed safety stop.
Cage Captain is in the cage with guests for the entire dive. Their role is to monitor guests comfort and alertness, and to liaise with the Dive supervisor on the surface. They are responsible for checking the underwater cage systems pre-dive, conducting diver safety tests for mask and ears and communicating to the surface for any information that is relevant to the safety of the dive. Under a worst-case scenario where the connection and retrieval systems fail, the cage captain will operate the emergency bailout to bring the cage to the surface.
Triple Dive Safety
To lead the way in industry standards in line with our best practice we have developed the Triple Dive Safety standard, which is designed to give two redundancies or backups – four major systems required for a safe bottom cage dive are: Air, Communication, Connection and Retrieval:
(1) Triple air supply: The primary source of air for all divers is Surface Supply through our dive compressor on the boat. This compressor is designed to provide enough air to both the bottom cage and surface cage at the same time. At all times during Bottom Shark Cage diving, the Dive Supervisor is stationed to monitor the primary and backup air supply.
To ensure air safety for bottom cage divers, we have two backups bottle-banks. Firstly, this consists of 4 x cylinders on the surface, which are monitored and controlled by the dive supervisor. These 4 cylinders are enough to provide air to 4 passengers for 2 hours. Secondly, there are 2 x cylinders located in the Bottom Shark Cage, which is enough to supply 4 passengers for 1 hour.
In the safety briefing cage supply, emergency air is discussed and a model is used to display and explain that any customer at any time can turn this air on if they feel short of air, no questions asked. They are asked to indicate to the cage captain if this is in fact engaged, so that if there is a failure of the surface supply the cage captain and the dive supervisor can communicate and solve the issue or make the decision to terminate the dive.
(2) Triple communication system: Audio Intercom System and Emergency Signal System to keep real-time communication between the Bottom Shark Cage and the boat. Thirdly we also have a video camera which is mounted on top of our Cage Captain’s full face mask, offering a wide-angle view from the ocean floor for all passengers at the surface. The audio Intercom system is built into our cage captain’s full face mask, which at all times maintains communication between the bottom cage and the dive supervisor on the boat. The signal rope supports three different coloured floats on individual quick releases as a backup emergency signalling system.
This is explained to bottom cage divers during the safety briefing and each diver is expected to indicate where the quick releases are located in the event of an emergency or if any diver at any time feels the need to communicate directly with the dive supervisor. This will trigger a termination of the dive returning the dive to the surface immediately, non-stop. We run a non-stop dive table with a precautionary safety stop. The Diver then exits the cage and if it is determined safe the dive supervisor will re descend the cage for a continuation of the dive.
(3) Triple Connect Point: Between the bottom cage and boat, hydraulic winch, our main steel cable for retrieval and two preventer cables which limit the dive to 18m. Additionally, we have a backup connection of ultra-strength Dyneema rope, which can also be used for retrieval.
(4) Cage retrieval system: Primary system for deploying and retrieving the cage is the davit and winch of the side of the vessel. This rated winch and cable is used for all dives. In the event of its failure there is a choice of two other cables that can be attached to the crane as a secondary method of retrieving the cage. If this is not possible then there is an emergency Bail out cylinder independent of the breathable air supply. In the event of a failure to retrieve the cage the cage captain is responsible to activate the emergency bail out system forcing the cage to float independently to the surface. This is considered a CEASER assent and is uncontrolled. upon retrieve of the cage and the safe return of divers to the vessel, all divers will go on O2 and all dive operations cease and the vessel will return to port immediately as a safety precaution.
Bottom Cage Dive Procedure
(1) Dive certificate reviewed in the office or on the boat.
We only invite divers with a PADI or SSI Open Water or equivalent certificate to join our Bottom Cage Dive. This is to ensure that passengers have essential understanding and knowledge about diving and the ability to deal with emergencies before they enter the Bottom Shark Cage. This ticket is to be presented on arrival.
(2) Pre-dive inspection (conducted by a staff member)
Our staff will use our pre-dive checklist to check our bottom cage system before operating the Bottom Cage Dive. This includes checks on all equipment involved in the dive operation, such as the primary, secondary and emergency air supply, the communication systems, the multiple connection points between the vessel and the bottom cage, as well as the equipment for retrieval of the cage. All these checks are documented.
(3) Dive briefing
Bottom Cage Diving is a unique dive experience and as such, a specialised dive briefing is delivered to all divers. This includes an overview of the dive procedure and the dive plan, as well as how the dive differs to a SCUBA dive – this dive includes the emergency systems, hand signalling, equalising, mask cleaning, allocation of positions within the bottom cage and a description of the unique flora and fauna that can be sighted at the Neptune Islands Marine Conservation Park. During the dive briefing customers are encouraged to share on previous dive experiences and ask any questions.
(4) Get in the cage – time for fun!
Final checks are done and then it’s time to put on the wetsuits, masks and weight belts, making sure that all gear is properly fitted. Customers are then invited down the ladder into the bottom cage to their designated position.
(5) Diver competency tests
Once all divers are safely in the cage, the Cage Captain will ask passengers to remove, clear and replace their mask, one by one. This will ensure that all divers can retrieve their mask if it is accidentally knocked off. Divers will all asked to drop to their knees and check that they can clear their ears from compression.
(6) Descend to 18 meters
The cage is slowly lowered to 18 meters, with our Cage Captain continually monitoring all passengers behaviour and comfort. They are communicating this to the Dive Supervisor. When we reach 18 meters, it’s time to take in the scenery and to enjoy the unique underwater world of the Neptune Islands Marine Conservation and Great White Shark territory
(7) Ascent to the boat, with safety stop
Once the agreed-upon maximum dive time is reached, the Bottom Cage will be winched to 5 meters depth, no faster than 18 m per minute. A 3 minute safety stop occurs to help off gas the nitrogen absorbed into muscles while diving. The ascent then continues to the surface to finish our Bottom Cage Dive adventure, where divers are welcomed back to warm showers and hot drinks and are invited to share their unique experience with the rest of the crew!