SeaNet--Ship/shore communications

Sea Technology, Jun 1998 by Myers, Gregory, Chayes, Dale, Goldberg, Dave, Maffei, Andrew

The SeaNet project (Sea Technology, May 1998) is a collaborative effort to extend the Internet to the oceanographic research fleet. By 1996, using transmission control protocol/Internet protocol (TCP/IP) over an INMARSAT B link, the SeaNet project had developed and operated a working prototype communications node that demonstrated the feasibility of on-demand Internet connectivity in remote ocean regions.

Nearly concurrently, the LamontDoherty Earth Observatory's Borehole Research Group (BRG) had initiated an effort to send wireline logging data acquired aboard the Ocean Drilling Program's (ODP's) JOIDES Resolution to shore-based data processing centers via high-speed transmission.

The BRG's goals are to decrease wireline data processing turn-around time, increase data quality control, and improve on-site decision making for safe and effective drilling.

On ODP's Leg 166, BRG began experimenting with using a very small aperture terminal (VSAT) to transmit logging data from the JOIDES Resolution to shore-based processing centers.

The system, though powerful and useful, had limitations in global coverage. That led to discussions with SeaNet, which was seeking a testbed for its developing satellite transmission system.

As useful as it is today, data transmission and processing via satellite will become even more vital to ODP in the future as drilling objectives generate larger and larger data sets (up to 20 kilometers of core per year) and involve longer periods on a single deep drilling site (possibly six months to 12 months). By using satellite transmission, both present and future benefits can be gained without increasing on-board personnel or compromising the security of proprietary data.

SeaNet Aboard Resolution

To determine the suitability of an INMARSAT B system for the wireline logging operations aboard the JOIDES Resolution, a SeaNet communications node (SCN) built around a Sun Sparc 5 processor and an ABB Nera Saturn Bm (an INMARSAT-B shipboard Earth station) was installed on the ship while in San Diego prior to the beginning of Leg 170 in October 1996. Since then, the unit has been undergoing a period of intense use and evaluation.

The installation was a joint effort between the LamontDoherty Earth Observatory, Woods Hole Oceanographic Institution, Texas A & M University (TAMU), and SEDCOFOREX (College Station, Texas) (formerly, South Eastern Drilling Co.). Working with SEDCO and TAMU to properly install the equipment, we installed the antennae on the roof of the dynamic position-shack and ran the cable to the radio room where the below-deck equipment was located.

The SCN control workstation, the Sun Sparc 5, was connected to the shipboard Ethernet network. Data to be transmitted could move from data acquisition to SCN via standard file transfer protocol (FTP) tools.

The SeaNet link employs PPP protocol over the entire link. The PPP protocol is carried on a synchronous digital link throughout the satellite-based segments and over an integrated services data network (ISDN) connection on the shore-side link and TCP/IP (Internet protocol) across the shipboard local area network (LAN).

Initial Results

During Leg 170, TCP/IP links were initiated and established by the shipboard INMARSAT B operator, typically a Lamont-BRG scientist without previous experience with shipboard communication equipment. While following a detailed procedure, the operator would place wireline-logging data on the SeaNet SCN computer and prepare to send the data to the shore-based data hub at WHOI. Once a connection was established, the SCN first transmitted the outgoing logging data and then retrieved files posted at WHOI that were awaiting return to the ship. Shore-based personnel awaited notification of a file transfer from the ship and then retrieved the transmitted files via FTP. Once data processing was complete, the processed files were posted on the data hub computer for retrieval by the ship.

During Leg 170 of the JOIDES Resolution (October 1996), 11 files for a total of 19.08 megabytes of wireline logging data were transferred over the SeaNet connection from the ship to the BRG analysis center at Lamont. In addition, two files of processed data totaling 1.54 megabytes were transferred out to the ship for use by the science party. Throughput for the ship-to-shore connections averaged 3.8 kilobytes/second and 1.7 kilobytes/ second for the shore-to-ship connections.

Benefits to Science Community

The INMARSAT B link provided the pathway for nearreal-time analysis of logging data, which enabled: Efficient means of transmitting geophysical and geological data to shore for processing Increased data quality control

Better on-site decision-making for safe, effective drilling. Wireline logging data transmitted from ship-to-shore for processing and then returned to the ship are routinely turned around in a five- to six-day period. This method of data delivery has reduced the extent of post-cruise data reprocessing and has reduced the time to deliver processed data to the participating scientific community following the completion of a leg. Transmitting logging data for rapid processing ashore has proven successful in enhancing the accuracy of shipboard logging data analysis, reporting, and increased data quality control.