The USS Monitor, a 987-ton armored turret gunboat, sank on New Year's Eve 1862 during a fierce storm 16 miles south of Cape Hatteras in 240 feet (72m) of water. The US Navy has recovered the engine, turret, and other artifacts and will display them in the Mariner's Museum in Newport News, Virginia. The Monitor Project was managed by National Oceanic and Atmospheric Administration's (NOAA) Monitor National Marine Sanctuary Program. Actual diving operations were performed by the US Navy.

Recovery of the Monitor's engine and turret was done in three phases. Phase I operations ended in April 2001 after divers safely reached the wreck and made observations and measurements needed by Navy engineers and salvage crews to recover the engine and turret. During Phase II, an Engine Recovery System (ERS) was placed directly over the Monitor's engine and the ERS lifted the engine during July 2001. Phase III prepared the gun turret, which was recovered in August 2002. Sixty-four bell runs were made for 125 dives during the 2001 operations. This summer saw 39 runs for 78 dives. The Global Industries saturation system was essential to the recovery operations.

The Saturation System
The TSS 1504 is comprised of two deck decompression chambers (DDC), a transfer lock (TL), and a submersible decompression chamber (SDC). Each DDC is designed to accommodate up to six divers and weighs approximately 38,000 pounds. The DDC chamber is eight feet high by 15 feet long by 84 inches in diameter. It has three ports: two seven-inch viewports and the third in the elliptical head of the dining and recreation area. Temperature is maintained between 75 and 95 degrees Fahrenheit and humidity controlled to range between 50 and 75 percent. Carbon dioxide is maintained at less than 5,000ppm. The lighting system used within the DDC is low voltage and each light may be dimmed individually. Each chamber occupant has an individual bunk light.

Each DDC is equipped with a Built-In-Breathing System (BIBS) capable of supplying the required gas at any depth. Exhaled gas is dumped overboard via a back pressure regulator.

The transfer lock is a vertical cylinder pressure chamber six feet, eight inches in diameter by seven feet, two inches in height. The lock permits access between the two DDCs or between the DDC and SDC. The TL contains the toilet, shower, and wash basin for use by both DDCs when saturated at the same depth. When DDC saturation is at different depths, the TL is available on a time-share basis. The TL weighs approximately 18,000 pounds.

The submersible decompression chamber, or bell, is used to transport the divers from the pressurized living quarters (DDCs) on the surface to the sea floor. The SDC is nine feet in diameter and designed to accommodate two divers. It weighs approximately 14,000 pounds fully outfitted and approximately 1,460 pounds submerged. The interior of the SDC is heated by the divers' hot water linked to a heat exchanger with a fan. Hot water temperatures may be controlled on the surface or by the diver within the SDC. The water may be routed directly to the diver or through an outside hull heat exchanger, mixing tank, and then to the diver.

Oxygen and carbon dioxide levels in the SDC are monitored and controlled from the control console van. An onboard scrubber system maintains carbon dioxide levels below 20,000ppm. There is an onboard emergency gas supply (2,200 cubic feet) in the unlikely event the surface gas supply is interrupted.

The SDC has a 2,000-pound releasable ballast weight secured by two through-hull penetrator release devices. These devices are rigged with safety pins to prevent an accidental release of the weight.

The SDC is handled with a hydraulically operated U-boom. A Norson hydraulic winch controls the 1,800-foot 1.25-inch diameter lift wire.

A hydraulically-powered umbilical assist winch handles the accompanying SDC umbilical. The SDC umbilical contains two breathing gas hoses, one hot water hose, four pneumo and sampling lines, and two electrical cables.

Surface 110 voltage is converted to 24 voltage before it enters the pressure hull to power the fan on the SDC heater, scrubber fan, and SDC internal lighting. An onboard battery pack provides back-up power for the lights CO2 scrubbers, and communications. External SDC lighting is powered directly from the surface.

A diver communications system provides communication between all components of the diving system and a wireless telephone system serves as emergency in-water communications backup.

The control console van (CCV) houses all breathing gas, electrical, and communications control, as well as all atmospheric and breathing gas instrumentation, TV monitors, etc. The Dive Controller or Diving Superintendent and the Life Support Technician man the CCV on a 24-hour basis during diving operations. SDC handling system controls are also located in the CCV and operated by the Dive Controller or the Diving Superintendent.

All pressure vessels contained in the system are certified by the US Coast Guard and the American Society of Mechanical Engineers. Divers are transported in the TSS 1504's diving bell to the sea floor and returned to the surface for reconnection to the pressurized living quarters. The system enables divers to remain at depth for as long as necessary to complete the job before decompressing. Prior to US Navy-approved use of the Global TSS 1504 saturation system, Navy surface-supplied divers were limited to 30-minute work sessions followed by three hours of decompression.

Naval Approval
The TSS 1504 required several modifications to satisfy military specifications and attain final certification by the US Navy. Once approval was granted, the TSS 1504 was ready for training and qualification of the US Navy dive teams for use in the recovery of the engine, turret, and other artifacts from the sunken USS Monitor, a challenging US Navy mission.

The US Navy inspection of the system was in March 2001. "This was a challenge for Global because of the very different requirements for Navy sat systems and commercial systems. It took a lot of hard work and cooperation by both the Global crew and the Navy divers to make this happen," said Bob Merriman, Global's Diving Equipment Manager.

The Navy's survey inspection team requested:

• Drawings (hull, piping, electrical) identifying testing requirements, weight handling requirements, design working pressures, cleaning requirements, weld/braze information, material identification for piping fittings and operational components, and a current (as is) configuration.
  Global Industries obtained complete sets of original drawings and traced the TSS 1504 system wire-by-wire and pipe-by-pipe to ensure that either the drawings were correct or were modified to reflect the current configuration of the 1504. The entire system was checked to ensure it conformed to the requirements of 29 CFR 1910 Subpart T, CFR 197 Subpart B, and ADC standards.
• Standardization of electrical systems to US Navy standard on electrical systems (AODC 035,060 and 062), an international standard. The use of this standard prompted several minor changes in the electrical system of the TSS 1504. The battery backup system was replaced with a shipboard-type UPS system with sealed batteries. The control van 120-volt electrical system was updated and ground fault interrupters were added. All electrical wiring was inspected for weather cracks and cuts, and replaced as necessary. Global purchased and installed video surveillance cameras on each DDC, SDC, and transfer lock as well as helmet-mounted cameras, lights on the divers' helmets, and an exterior SDC camera.
• Certification of the handling system by ABS Underwater Vehicles, Systems and Hyperbaric Systems, Appendix D.

ABS will not certify an existing system. Therefore, Global proposed a witnessed load test by ABS. The Navy agreed to this and it was done. In addition, all gas piping used with helium, oxygen, and mixed gas was cleaned for oxygen service. A "clean room" was established at Global's Carlyss, Louisiana, facility for cleaning regulators and other small components of the system. The practice of sealing the open ends of hoses and fittings was stopped and Global began using either plastic or metal caps.

A toxicity test on the entire system was required. The US Navy provided sample bottles, particulate filters, etc., as well as a list of locations where the samples were to be taken. This was done and all samples were satisfactory.

Global replaced all bedding with a US Navy-approved type and checked all wiring and electrical components inside the system to minimize any flammability concerns. At the USN's request all system viewports were replaced.

Global provided the Navy with a copy of all maintenance records and procedures and implemented a modified system that conformed to their system of record keeping.

Further, Global outlined the in-house safety program and met with the USN and the Global safety representative to address any concerns USN had. There were no concerns.

Other tests and procedures to meet US Navy requirements:

• Pressure test to 1500 FSW witnessed by NAVSEA,
• 125 percent static load test on the bell boom,
• 100 percent dynamic load test on bell handling system,
• Pressure drop test on the entire system,
• Leak tests on all fittings at both high and low pressure.

The TSS 1504 was approved for US Navy use in June 2001.

Training of US Navy Divers on TSS 1504
During the training sessions a dive protocol was written to establish all dive parameters to the US Navy's satisfaction. Watch station duties and dive procedures were written as per the US Navy supervisor's requirements.

Training to prepare the US Navy divers to operate the TSS 1504 Saturation System was conducted first in Carlyss, Louisiana, then Houma, Louisiana, during loadout and set up on the barge, and during the actual tow from Houma to Cape Hatteras.

The Carlyss training included bell handling system training for Navy personnel operating the handling system while on the Monitor site. All valves and fittings were numbered in preparation for training in setting up TSS 1504 for different functions (bell diving, decompression, emergency systems, etc.). The system was also prepared for transportation to the barge, resulting in on-the-job training for Navy hands.

The Houma training was conducted during loadout and setup on the barge. It included proper set up procedures for a saturation system, flange-up of major components and gas hook-ups, and operational procedures for pressure tests and leak checks. There were setup and function tests of the divers' hot water system, emergency power system, and the chamber water and sewage systems. Tests and evaluations of all systems were made to determine readiness for diving.

The training conducted during the tow to USS Monitor site included setup and operation training on all systems of the 1504 for the Navy Saturation Divers.

Finally, training conducted on all systems included:

• C02 and 02 analyzer calibration and usage
• Valve alignment and setup procedures
• Electrical system setup and test including backup power supply
• Press divers conduct all systems tests and calibration
• Emergency procedures and backup systems.

Upon arrival in Cape Hatteras, on site and at anchor, Global supervised drills on bell operations and conducted an unmanned test dive to 230 feet (70m). Each diver qualified as a bell operator or watch stander.

Conoco's Jolliet Project
Prior to its use on the Monitor project, the TSS 1504 was used to perform hook-up work for Conoco's Jolliet Project in the Gulf of Mexico's Green Canyon Block 184. The scope of work included two eight-inch and two 10-inch flange connections in 1,075 feet (326m) of water, and one eight-inch and one 10-inch flange connection to join flexible pipe to steel pipe in 1,015 feet (308m) of water.

Six divers were saturated to a storage depth of 980 feet (297m) over a period of 72 hours and later decompressed according to US Navy Saturation Tables. The divers worked in two-man shifts, with each diver working a maximum of three hours in the water. Umbilical lengths were kept to a maximum of 80 feet. The total time for each diving bell run was eight hours. UW