Seagliders fly through the water with extremely modest energy requirements using changes in buoyancy for thrust coupled with a stable, low-drag, hydrodynamic shape. Designed to operate at depths up to 1000 meters, the hull compresses as it sinks, matching the compressibility of seawater.

The AUV Seaglider is the result of a collaborative effort between APL-UW and the UW School of Oceanography. These small, free-swimming vehicles can gather conductivity-temperature-depth (CTD) data from the ocean for months at a time and transmit it to shore in near-real time via satellite data telemetry.

Seagliders make oceanographic measurements traditionally collected by research vessels or moored instruments, but at a fraction of the cost. They can survey along a transect, profile at a fixed location, and can be commanded to alter their sampling strategies throughout a mission.

• Physical, chemical, and biological oceanography
• Tactical oceanography
• Maritime reconnaissance
• Communication gateway
• Navigation aid

• Survey: transits a sequence of waypoint targets
• Virtual mooring: profiles at target location
• Loiter and drift: maintains neutral buoyancy at any depth
• Loiter on bottom: maintains negative buoyancy
• Surface: positions antenna mast for GPS/RF data telemetry

• First to complete >3800 km mission
• First to complete >7 month mission
• First to conduct multi-glider mission

Seaglider Probes Dabob Bay and Hood Canal. The Office of Naval Research funded Seaglider's participation in AUVFEST 2005, the sixth such event, over a period of two weeks in June. The glider was launched on the 9th and profiled continuously over 40 horizontal nautical miles through the 15th.

Making 180 dives to 100 m, the glider measured temperature, conductivity, and dissolved oxygen and computed surface and depth-averaged current onboard for each profile. Upon reaching the surface, the glider telemetered data ashore and received waypoint and command file updates.

The shore server immediately formatted temperature, salinity, and ocean current data into standard Navy formatted messages and emailed them to NAVOCEANO where they were "bent-piped" in real time back to the AUVFEST command center. An on-site NAVOCEANO representative assimilated the profile data in a PC-Tides model as part of the AUVFEST demonstration.

Twice SG022 was commanded to rendezvous and station-keep at a common waypoint with two or three Slocum gliders flown by Alaskan Native Technologies and SPAWAR. Over the last 36 hours of operation, the glider was flown in a double-bow-tie formation to demonstrate the effectiveness of its Kalman filter to deal with tidal fluctuations.

A bonus to this exhibition deployment was the demonstration of the glider's capability to acquire dissolved oxygen data that could contribute to the study of oxygen deficiency in Hood Canal.

SG022 participated in AUVFEST on the heels of a record-breaking AUV mission as part of the North Pacific Acoustic Laboratory experiment. Launched in the central north Pacific Ocean on 14 September 2004, SG022 traversed 1800 horizontal nautical miles and made nearly 600 dives with sister glider SG023; they were recovered six and a half months later in mid-April off the southern shore of Kauai.

Seaglider Soars as Remote Environmental Sensor. The Office of Naval Research funded an initiative to have a Seaglider participate in a Navy ASW exercise called TASWEX-04 in the East China Sea in October 2004. Craig Lee of the Ocean Physics Department, APL-UW, offered one of his Davis Strait gliders, SG-017, and Tim Wen of the Ocean Engineering Department was the APL-UW technician aboard the USNS Bowditch, TAGS-60 with the glider. Pilots were Dr. Craig Lee and Neil Bogue, APL-UW; and Dr. Charlie Erikson, UW Oceanography Department.

Mr. Wen was responsible for the launch, monitoring, and recovery of Seaglider as it probed an oceanographically dynamic shelf-break environment to discover the boundaries of the Kuroshio current. This was the first time Seaglider had been piloted in such an active environment.

The exercise was sponsored as part of the Navy's Task Force ASW Initiative, a major Chief of Naval Operations initiative that has the Navy's attention because of Seaglider's potential for improving the Navy's ASW capability in diesel submarine conflicts. This represents an expansion of Seaglider's traditional design role as a deep ocean profiler.

TASWEX-04 was the second time that Seaglider has engaged in Navy-related activities. SG-019 participated in RIMPAC-04 in June and July, completing 374 successful profiles over 170 horizontal miles in 25 days before experiencing command, control, and communication difficulties. The Navy came away from RIMPAC-04 excited about the potential such vehicles may bring to both environmental assessment of the undersea battle space and tactical remote sensing.

On June 15th Seaglider 019 was launched in deep water south of Oahu from the U.S. Navy torpedo retriever Chaparral TWR-7. From here it began six weeks of operation in support of the U.S. Navy exercise RIMPAC-04—an international exercise involving navies from eight nations. Dr. Tom Swean of the Office of Naval Research, funded APL-UW to build both a glider and participate in a Navy exercise with the Seaglider. APL-UW prepared, shipped, final-prepped, launched, and is operating and collecting data from the glider.

Engineer Keith Van Thiel, donning a snorkel mask and fins, helped the glider out of its cradle as it was eased overboard. Keith took the first-ever uderwater photos of the glider as it dove in deep, sky-blue, very clear water. A small preset error took some head-scratching to work through, but the glider was on its way by 1400 local time on 6/15 and has been flying very well since then. With the valuable assistance of Neil Bogue and Jim Bennett of the UW School of Oceanography, Principal Engineer Jim Luby piloted the glider for the second time—the first being Seaglider 019's maiden voyage in Port Susan, WA, in late April.

The data acquired from the glider is distributed in near-real-time to NPMOC Pearl Harbor, NPMOC San Diego, and NAVOCEANO during the exercise. Senior Physicist Marc Stewart, who assisted aboard Chaparral with the launch, has worked continuously with Navy meteorological and oceanographic (METOC) personnel both at Pearl Harbor and San Diego since the launch to analyze and process Seaglider's data, evaluate the effects that the glider data is having on Navy ocean and acoustic propagation models and tactical decision aids, coordinate glider piloting with the Navy submarine community, and discuss operational concepts.

Temporally relevant environmental information, in the form of temperature initialization files suitable for fleet MODAS users, is distributed to air, surface, and submarine ASW end-users. Fleet units will assimilate and apply the information and develop time-dependent sensor performance predictions as a basis for their sensor performance predictions and, hence, sensor employment decisions.

The glider is commanded at various points along the way with the following objectives in mind:

• Show that glider profiles can improve fleet ASW capability (i.e., demonstrate flow of glider data that merges into MODAS/Lite, demonstrate value of capturing diurnal variability via "Day and Night" MODAS fields sent to fleet for optimizing sensor/platform placement and sensor settings, and extrapolate value of having more than a single profiling glider in battle space preparation)
• Demonstrate ocean acoustic variability to fleet and its contribution to sensor performance uncertainty
• Show that glider profiles can improve fleet MIW/SPECWAR capability - Demonstrate flow of glider data that merges into MEDAL and MIW/SPECWAR operators (surface, depth-averaged current)
• Show glider command and control supports COMSUBPAC Water Space Management, MIW/SPECWAR communities
• Demonstrate connection between glider data and Navy Coastal Ocean Modeling
• Demonstrate glider launch via Navy platform

The scientific motivation behind this exercise is to see how well the Seaglider can resolve diurnal variability of the vertical structure of the water column and, possibly, the subtle variability of the water column caused by the background internal wave field. To do this, the glider is commanded to make a profile across a shallow portion of the thermocline repeatedly to depths of 75–100m. This is necessary to capture higher frequency phenomena of the upper water column.

Seaglider, an autonomous undersea vehicle, is used in oceanographic research missions where measurements of salinity, oxygen, and chlorophyll over large spatial and temporal scales are needed, especially in inhospitable environments.

uwhuskies YouTube video (run-time 2:40)

The Integrated Observational Platform (IOP) lab at the University of Washington's Applied Physics Lab regularly tests and deploys seagliders, buoyancy-driven autonomous underwater vehicles (AUVs). On 22 Dec 2007, a field team recovered a seaglider from testing in Port Susan, during rough conditions. Keep an eye out for logs rolling in the waves!

YouTube video (run-time 2:46)

This animation demonstrates how Seaglider moves through the ocean and communicates with satellites to transmit data and determine its global position. As Seaglider dives and ascends its wings cause it to glide, allowing horizontal movement. Internal sensors monitor the depth, heading and attitude of the vehicle. External sensors are constantly scanning the ocean to determine water properties. The animation is a 3D simulation of how Seaglider maneuvers. Cut-away views of the internal mechanics show how Seaglider pitches, rolls, dives, ascends, and surfaces.

(Note: There is no audio.)

YouTube video (run-time 4:15)

General Manager: Frederick (Fritz) Stahr, Ph.D. | 206.543.7886 | stahr@ocean.washington.edu