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Alvin Scientific Equipment Interfaces


Alvin personnel will direct the installation of all science equipment and will make necessary interconnections to the submersible. Because the number of persons available for this work is limited, it is recommended that the user test his equipment prior to installation and resolve all interface questions through early consultation with the Alvin Group. Appendix B contains information on the acoustic operating frequencies of equipment aboard Alvin and Atlantis which may have a bearing on the design or adaptation of certain science equipment. Weights of all equipment to be used on Alvin must be known, i.e., the air weight for equipment to be installed in the sphere and both the air weight and the weight in salt water for outside equipment. This information should be given to the Expedition Leader prior to ship departure.

Pressure Housings

Certification of implodable volumes to be used with Alvin normally requires a submergence pressure test to 10,200 psi for 10 cycles; held 10 minutes at greatest pressure for cycles 1 through 9, held 1 hour at greatest pressure for cycle 10. An alternative procedure involves substituting a different maximum test pressure in the same cycling sequence according to the following equation:

Test pressure (psi) = 1.5 x (max pressure (psi) expected during applicable dives)
where maximum pressure = maximum water depth (meters) x 1.487 (psi/meter)

Either method will be accepted, but it should be noted that use of the computed pressure method limits use of the housing to the corresponding water depth. Leakage or visible signs of external damage shall be cause for test failure. Where several housings of a particular type are to be utilized, each housing shall be pressure tested; i.e. representative testing of one vessel in a series will not be accepted. Each vessel tested must have a unique identification number referenced on all related test documentation.

Although pressure test certification for Alvin purposes does not expire, consideration should be given to testing every five years. The Expedition Leader may refuse to honor a valid certification if he feels the condition of the housing has deteriorated since its last pressure test. Modifications to the housing such as machining, drilling etc. void a pressure certification and thus the vessel must be tested after any work that could compromise structural integrity.

The test chamber pressure recording chart (or copy) and/or statement of test details signed by the chamber operator shall be delivered to the Alvin office at Woods Hole, and a copy shall be delivered to the Expedition Leader aboard Atlantis prior to ship departure and subsequent equipment installation on Alvin. See Appendix I (pdf) for a sample record.

Pressure vessels constructed from certain experimental or unpredictable materials such as glass or ceramics cannot be certified for use with Alvin in the manner described above. In some cases, a design review by Alvin’s U.S. Navy engineering oversight body (NAVSEA) is required (a time-consuming process) and in others, certification is impossible. If in doubt about a particular design or if you are suspicious that the Expedition Leader may have doubts, contact the Alvin office.

Glass Flotation Spheres

Glass flotation spheres deserve special mention because of their common usage; these spheres cannot be certified by pressure testing because of their susceptibility to failure as a result of minor damage. As a consequence, Alvin will handle instruments utilizing these spheres in only three ways:

  1. An instrument using glass spheres for flotation will be carried to or from the bottom by Alvin provided the spheres are tethered above the instrument at a distance of at least 100 meters
  2. Alvin will move an instrument on the bottom (including limited vertical excursions) provided the flotation spheres are tethered at least 30 meters above the instrument
  3. Alvin will approach a glass sphere on the bottom to within photographic range but will not touch it. The only exception here is the case where Alvin approaches to grasp a trigger or release lanyard which is long enough to allow the submersible to back away a suitable distance before activation

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Standard 19-inch rack space, up to 35 inches in height, is available for instruments to be mounted inside the pressure hull. This space is variable depending on submersible load. Depth behind the rack varies from 14 to 18 inches, as shown above.

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All the wires in the port and starboard J boxes may be extended forward to the science basket disconnect boots. The figure above shows the general arrangement of these junction boxes.

Electrical Systems

Standard 19-inch rack space, up to 35 inches in height, is available for instruments to be mounted inside the pressure hull. This space is variable depending on submersible load. Depth behind the rack varies from 14 to 18 inches, as shown to the left.

All equipment used inside the personnel sphere must fit through a 19” diameter ring to assure adequate clearance through the hatch. A panel mounted at the top of the science rack contains 12 and 26 VDC power for instruments and the termination of wires entering the hull from the external science basket area and junction boxes.

Four separate 26 VDC power circuits are available on the science panel. One of the circuits has a 10A breaker and three have 5A breakers; two of these circuits are remotely switched from a panel near the starboard observer. 26V power for devices requiring more than 10A is available by connecting directly to the 50A breaker that supplies the panel. Although the panel breaker is rated at 50A, the actual power available is dependent on other submarine requirements; a total of 100A of 26V is produced, of which 25-50A can be used by permanent equipment (described below).

Similarly, there are four 12V circuits with 10A circuit breakers, two of which can be remotely switched; a total of 33 amps of 12V is available.

At the bottom of the science rack there are two 12V airline-style jacks into which users can plug notebook computer power adapters. These jacks are identical to what you would find on an aircraft, and adapters are sold by a number of vendors (Targus, Fellowes, Kensington, etc.). The jacks are connected to a 12VDC breaker.

1,000 watts of 115VAC 60Hz power is available from an inverter powered from the 120V bus. The CTFM sonar consumes aprroximately 70 watts of this power when operating.

See Appendix C for information on power budgets and typical power available for science use.

All of Alvin’s electrical systems and through-hull wiring must be UNGROUNDED to limit the chance for corrosion of structural parts in the event of inadvertent grounding of any conductor. Alvin’s electrical systems are frequently checked for grounds during each dive. There are four requirements that each science device must meet: 1. No device may permit, or cause, a direct DC path between any source of Alvin power and the submarine’s hull, frame or seawater.

2. No device connected to through-hull wires may permit any DC path between any through-hull wire and the submarine’s hull, frame or seawater.

3. All devices connected to through-hull wires must provide a DC path from an Alvin power source to all such through-hull wires so that the submarine’s ground detection system can be used to check for inadvertent grounding of through-hull wires. The easiest way to provide this connection is with a resistance of from 0 to 3 Kohms between the instrument’s internal ground and the input power common (for DC powered equipment). An alternative to this requirement is for the instrument to provide a means of continuously monitoring the through-hull wires for ground.

4. Isolated or battery-powered equipment may not be used to avoid these requirements.

Wires leading from inside the sphere are available for science use and terminate outside the submersible as follows:

Junction (“J”) boxes
  • Sail (forebody): 25 singles & 2 twisted shielded pairs
  • Port (afterbody): 22 singles & 3 twisted shielded pairs
  • Starboard (afterbody): 18 singles & 2 twisted shielded pairs
All the wires in the port and starboard J boxes may be extended forward to the science basket disconnect boots.

The second figure shows the general arrangement of these junction boxes.

All single wires are #16 AWG and are rated at 13A. Shielded pair wires are #18 AWG. All wires are fused at 10A. Outboard scientific equipment to be wired into any of the above must be fitted with a suitable length (normally 15 feet) of an oil compatible cable; Teflon insulated wire/polyurethane jacketed cable is recommended. Acceptable jacket outside diameters for user-supplied cable are 0.148, 0.290, 0.420, and 0.750 inches, since these sizes will fit standard Alvin stuffing tube packing assemblies.

Equipment and devices may be externally mounted on the forebody structure (sponson, light bar, sail). The exact location and mounting method will be at the discretion of the Alvin Group. Forebody-mounted equipment must terminate in a forebody J box in order not to interfere with emergency release mechanism of the forebody. Cables from installed devices must be of sufficient length to reach and enter the J box (filled with Bray 726 oil). Cables will enter the J box through a stuffing tube and therefore will fill with compensating oil unless dammed or otherwise blocked. Polyurethane cable jacket is preferred over neoprene/SO types because of it's superior oil resistance.

Afterbody-mounted equipment (below viewports, aft of sphere) must terminate in the Port or Starboard J boxes. Science basket-mounted equipment must terminate in one of the three science pull-apart disconnect boots, which allow the basket wiring to separate from the submersible in the event that the basket has to be jettisoned. These disconnects are located on the skin under the forward viewport and are also filled with Bray 726 oil. Wires from science equipment in the basket must be long enough (15 feet) to reach these disconnects. This PDF file shows the general layout of a science disconnect boot. Appendix D lists the wires available at each of the three science disconnects and can serve as a set of worksheets to help allocate signals to the wires.

This information is provided to assist the user in preparing wiring harnesses and checking the operation of equipment with the completed harness well in advance of a cruise. The circular plastic (CPC) connectors depicted plug together as well as directly to the Alvin through-hull wiring. The Alvin wiring has a one-to-one correspondence with these connectors, minimizing the chance of wiring errors which helps expedite final equipment installation. The connectors, pins and tools are available from most major electronics suppliers.

The inboard CPC connector terminates at the top of the science rack, located at the rear of the personnel sphere. Power for science applications is provided in this same panel (see above for number of 12V and 26V circuits). 120VDC service (protected at either 80A or 15A) can be installed outside and controlled from within the sphere to operate afterbody-mounted equipment.

Data System

The Alvin data system consists of multiple Alvin computers and various measuring instruments. The Alvin computers are IBM compatible with PIII processors and 128MB of memory running the Win2000 operating system. USB, RS-232, RS-485 and ethernet interfaces are available; contact the Alvin Group to discuss use of these ports. See Appendix A for a list of standard data available.

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Alvin's video system.

Video System

The Alvin video system provides independent selection of any of eight video sources to each of up to four monitors and up to four recorders. In addition, the monitor images can include text overlay generated by the datalogger, and the recorded signals include LTC timecode.

The normal complement of equipment includes:

  • A 3-chip color video camera mounted on the starboard manipulator. This camera is capable of 800 TV lines of resolution and has a 10X zoom.
  • Two single-chip color video cameras, mounted on the forward sponson, with individual pan & tilt. These are capable of 470 TV lines of resolution and have an 18X zoom. One of the cameras has a pair of laser pointers attached, which project beams normally 10 cm apart on the image.
  • A downward-looking silicon itensified target (SIT) camera mounted in the battery bay. This is capable of very low light image capture at 500 TV lines of resolution.
  • Three color monitors for in-hull viewing.
  • Two DSR-50 DVCam recorders.
  • A digital video frame grabbing system that provides medium resolution video stills. Click here to learn more about this system.
See the Scientific Subsystems section of the User Manual for information on media types and policies.

The Alvin video system is designed and built to provide the best recorded image quality. All of the equipment is fully compliant with NTSC, RS-170, RS-170A and S-VHS video. The timecode equipment is compliant with SMPTE LTC timecode standards.

An NTSC blackburst signal (RS-170A) is available for all external cameras and is available to in-hull equipment to provide for synchronization. While the Alvin video system imposes no requirements for video sources to be synchronized, they are expected to be and the use of this feature will result in a better recorded product.

Composite, S-VHS, RGB, Y/R-Y/B-Y and YUV signaling are all supported from the camera sources, though not simultaneously. All signals are terminated at 75 ohms and buffered for distribution using buffers that are compensated for cable loss.

The mating connector for an external camera is a Kemlon 16-B-5690-12 12-pin PWCF. Cameras should be fitted with Kemlon 16-B-6379-01 12-pin male PWMF (or equivalent) connectors. External cameras are provided with the following signals:

Power: Two wires (TSP) to provide 26V, fused at 1A
Signal: Two wires (TSP) for camera-defined command signaling
Genlock: One coax (RG179) to send blackburst to the camera
Video: Three coax (RG179) for video from the camera for
simultaneous transmission of Composite and Y/C
video. For component cameras, R is on the Y coax,
G is on the C coax, B is on the Composite coax.
Pin 1: Signal LO
Pin 2: Signal HI
Pin 3: Power +
Pin 4: Power Return
Pin 5: Genlock
Pin 6: Genlock shield
Pin 7: Composite (or B) video
Pin 8: Composite shield
Pin 9: C (or G) video
Pin 10: C shield
Pin 11: Y (or R) video
Pin 12: Y shield

All cabling is provided on continuous runs of either RG-179 coax or shielded pairs as appropriate, except for possible short lengths of discontinuity at terminal strips, penetrator and connectors. These are intentionally minimized to prevent degradation of the signals.

To preserve performance and reliability of user supplied cameras, it is recommended that they comply with this connector and pinout arrangement.

The standard equipment cameras provide both Composite and S-VHS signals. All three are equipped with focus and zoom capabilities, and a fully featured controller. Since they switch between optical and electronic zoom seamlessly, it is recommended that the electronic zoom be disabled unless it is necessary for the desired operation.

Each in-hull monitor is provided with an independent source selection control and data overlay control. Normally, three monitors are installed leaving one additional monitor port available. Each can be selected to view any of the eight video sources, and can have the overlay selected on or off. Selecting the overlay off does not change the contents of the overlay, only makes it not visible; the contents of the overlay are always controlled by the datalogger.

The standard equipment recorders are Sony DSR-50. Normally, two decks are installed leaving two additional recorder ports available. These decks record the S-VHS video signal from the selected source, along with in-hull audio and LTC timecode. The disposition of these tapes is controlled under the NDSF Film, Video and Data Archiving Policy.

Each recorder is provided with an independent source selection control. Each can be selected to record any of the eight video sources, or can be slaved to record from the same source as any of the in-hull video monitors. See Appendix J (pdf) for a sample of the form investigators use to specify sources for recording. These recordings do not normally include text overlay.

There is also a provision to record the same signal as displayed on the port observer’s monitor. In this case, the recorded signal will be of NTSC format, and will include text overlay as shown on the observer’s monitor.

Hand-held video camera
A hand-held high-definition digital camcorder (Sony HDR-HC9 MiniDV as of August 2009) is available for use by the observers for shooting through the viewports. Its effective range extends approximately 2 meters beyond the viewport. Lighting is supplied by external viewing lights. Digital tape is not provided for this camcorder and tapes made with this system will not be archived. Only Sony DVM60PR2 or Fuji DVM60AME miniDV tapes are suitable for use in this camera.

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The figure above depicts the pump flow and pressure characteristics of the Alvin hydraulic system. The pump is a variable displacement pressure compensated open loop pump.

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Six independent hydraulic control valves are available for science use. There are four variable flow control valves and two solenoid directional control valves. Additionally, all valve outputs are connected to pilot check-relief valves as shown in the fluid power graphic diagram above.

Science Hydraulic System

The Alvin hydraulic system may be used to power or control scientific equipment. Hydraulic powered science equipment is mounted on either the Alvin afterbody or the science basket. The first figure depicts the pump flow and pressure characteristics of the Alvin hydraulic system. The pump is a variable displacement pressure compensated open loop pump.

When designing equipment for use with the Alvin hydraulic system, the user should be aware of several factors. The flow versus pressure shown above is for the total flow available for all the Alvin hydraulic systems (ie. submersible systems and science). If installed submersible equipment is used, such as manipulators, the flow and/or pressure may be reduced. Users should allow for a 100 to 300 psi pressure drop between the pump and science equipment, depending on flow and operating temperature. For high pressure applications (1700-1800 psi) a maximum total flow of 2.2 gpm would be available. For low pressure applications (< 800 psi) a maximum total flow of 3.5 gpm would be available.

When the port manipulator arm is activated, the oil flow is diverted away from other functions and priority is given to the manipulator. This can cause interruptions and/or reductions of performance in other hydraulic functions that are operating. The port arm requires up to 3 gpm and can use all the available flow for short periods of time. If uninterrupted use of science hydraulic operations is required, do not use the port manipulator arm when the science hydraulic system is on.

The hydraulic oil used in the Alvin system is per MIL-H-5606. High pressure 10 micron and water removal filtration is provided. Despite these precautions, the hydraulic system cannot be considered “clean”. Therefore, science equipment using the system must be designed to operate with potentially contaminated oil.

User hydraulic supply and return flow is supplied by flexible hydraulic hose supplied by the Alvin Group and connected to hydraulic manifolds on which the control valves are mounted. The hoses are terminated with 1/4" Swagelok fittings. Hoses used to supply equipment mounted on the science basket must pass through a hose cutter to allow emergency release of the basket. The space available in the cutters is limited, therefore to avoid difficulties, it is important to contact the Alvin Group in advance of intended use of the science hydraulic system.

Six independent hydraulic control valves are available for science use. There are four variable flow control valves and two solenoid directional control valves. Additionally, all valve outputs are connected to pilot check-relief valves as shown in the fluid power graphic diagram at the left. These check-relief valves provide load locking to the limit of the relief valve.

The science valve identifying numbers, valve types and relief settings are:

Valve No.Valve TypeRelief Setting
V3 Variable 2000 psi
V4 Variable 1000 psi
V5Solenoid 2000 psi
V6 Solenoid 1000 psi
V7 Variable 2000 psi
V8 Variable 1000 psi

The control valves are normally operated from a panel in the personnel sphere by the pilot. Solenoid valves are controlled by double pole, double throw (direction A or B), momentary, center-off toggle switches. The variable control valves work in a similar manner, except that the direction toggle switch connects the selected valve coil with a potentiometer that regulates the coil current and hence the valve flow in the direction selected.

Users may supply their own electrical controller for the science hydraulic valves by connecting to the User Hydraulic Connector. The connector is located in the personnel sphere near the starboard viewport. The connector is an AMP CPC Series 1, 24-socket plug, Type 206837-1. Users can terminate their cable with a suitable mate. Contact the Alvin Group for more information and other requirements for use of this option.

Chemicals, Isotopes and Explosives

Chemicals used in conjunction with experiments outside the sphere must be compatible with Alvin’s acrylic plastic windows, electrical wiring, and other equipment. Radioisotope work may be conducted only with prior permission from the WHOI Isotope User’s Committee (see the Atlantis User Manual or contact the Marine Operations Coordinator). Explosive devices may not be used in proximity to the pressure hull. Contact the Alvin Office if you have questions about any of the above.

Last updated: February 18, 2007