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OCR for page 138
5
Related Facility Needs for an Ocean
Observatories Network
Both the installation and maintenance of ocean observatories and the
conduct of complementary scientific studies will place significant de-
mands on the UNOLS fleet as well as on deep submergence assets in the
U.S. oceanographic community. In many cases these needs can be met
using vessels and deep submergence vehicles currently available within
the academic community; in other cases additional assets will need to be
added to the academic pool or leased from industry. This chapter offers a
preliminary assessment of these needs, although a more thorough study
is currently being undertaken by a UNOLS Working Group on Ocean
Observatory Facility Needs.
SHIPS
Ship requirements for the OOI can be broadly divided into two
phases: (1) installation and (2) maintenance and operations. These re-
quirements differ significantly for moored buoy and cabled observato-
ries, as summarized in Table 5-1.
Moored Buoy Observatories
Installation Ship Requirements
Many of the sites functioning as part of the global network will utilize
buoys and moorings that are similar to present surface and sub-surface
138
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RELATED FAC/~/TY NEEDS FOR AN OCEAN OBSERVATORIES NETWORK 139
moorings; the hardware on the seafloor for such sites will be similar to
presently deployed oceanographic instrumentation. These buoys can be
installed by a large, global-class UNOLS vessel, which provides the carry-
ing capacity, cranes, sea-keeping, and endurance characteristics needed
to work at most global locations. Buoys that are acoustically linked to
seafloor instruments will not require an ROV for installation. Those buoys
are linked by an EOM cable to a seafloor junction box, however, they will
require a deep-ocean ROV for installation of the junction box and seafloor
instruments. One month of ship time use should be anticipated per site,
allowing time for transit, extra days for weather, and extra days for uncer-
tainties (such as those associated with which ports are assigned), and
roughly a week for working at the site (i.e., time for recovery, deploy-
ment, in-situ comparison of shipboard and observatory sensors, and ship-
board science at the observatory site) (Table 5-1~.
Both high-latitude sites and sites where high-bandwidth is desired
will require larger buoys capable of stability in high seas and of support-
ing on-board power generation. A candidate 40 meter (approximately)
surface spar buoy was described in the DEOS Moored Buoy Observatory
Design Study (2000), but its size and amount of mooring line exceed the
capabilities of even the largest UNOLS vessels primarily due to their lack
of deck space and reel and winch capabilities (DEOS Moored Buoy Obser-
vatory Working Group, 2000~. Commercial offshore Class 2 construction
vessels, anchor handling tug boats, and Navy fleet tugs are all ideally
suited for launching the spar and mooring and could be chartered for this
purpose (Figure 5-1~. The subsequent installation of the topside module
and instrumentation, seafloor junction box, and seafloor instruments
could then be performed by a large UNOLS vessel (or its commercial
equivalent) after the spar and mooring have been installed, although some
special handling equipment would be required on the vessel and opera-
tions would be weather sensitive. While a commercial tug could be used
to tow the buoy, a large, capable vessel would have the ability to carry the
spar buoy on deck and could carry more than one spar buoy at a time.
Such a vessel would offer the advantages of faster transit and protection
from buoy wear and tear from towing. The ship will require dynamic
positioning capability and a deep-ocean ROV in order to install the sea-
floor junction box and instrumentation.
Coastal moorings like those envisioned for the Pioneer Array or for
long-term time-series sites are fairly simple to install using small or inter-
mediate-class UNOLS vessels or their commercial equivalent. Allowing
for installation of buoys and moorings, in situ comparison of shipboard
and observatory sensors, and weather contingency time, about two days
of ship time per mooring is estimated.
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140
ENABLING OCEAN RESEARCH IN THE 2 lST CENTURY
TABLE 5-1 Estimated Ship Time Needs Associated with OOI Global,
Regional and Coastal Observatories
Observatory Type Specifics Number of Nodes Ship type
Global Moorings Installation low-bandwidth 1 node/ 10 sites UNOLS
Global Moorings Installation high-bandwidth 1 node/ 5 sites Industry
UNOLS (
Global Cable Re-use Installation minor move 1 node/ 5 sites UNOLS
Global Moorings or Maintenance high-bandwidth and 10 UNOLS
Cabled severe environment
Global Moorings Maintenance Mid-latitude/Tropical 10 UNOLS ~
Regional Cabled Installation of backbone cable loops 2 ship in'
Regional Cabled Installation of nodes/core sensors 30 UNOLS
Regional Cabled Maintenance of backbone cable Industry
Regional Maintenance of nodes and sensors 30 UNOLS
Coastal Moorings Installation 75 UNOLS
Coastal Cable Installation 1-2 Cable la'
Coastal Moorings Annual maintenance 75 UNOLS
Coastal Cable Annual maintenance <5 UNOLS
NOTES: Assumptions: Global observatories 20 global nodes, including 10 low-bandwidth
acoustically-linked or cabled-linked moorings, 5 high-bandwidth, cable-linked moorings,
and 5 cable-reuse nodes with sub-surface moorings; annual maintenance assumed at all
nodes. Regional observatories 3700 km of cable and 30 nodes; 1 week/node to install
node and core sensors; annual maintenance of nodes and core sensors. Coastal
observatories two 30-node Pioneer Arrays and 15 cabled or moored long time-series sites.
Note: table does not include science ship time requirements beyond those required for
annual observatory operation and instrument maintenance.
SOURCES: Based on data from DEOS Moored Buoy Observatory Working Group, 2000;
and NEPTUNE Phase 1 Partners, 2000.
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RELATED FAC/~/TY NEEDS FOR AN OCEAN OBSERVATORIES NETWORK 141
obal,
of Nodes
Ship type
Ship-months
Comments
10 sites
5 sites
5 sites
UNOLS global class 10 (one time)
Industry charter (1 leg)
UNOLS (1 leg)
UNOLS global class
UNOLS global class
UNOLS global or ocean class
2 ship industry cable laying
UNOLS global class
Industry cable laying
UNOLS global or ocean class
UNOLS regional class
Cable laying
UNOLS regional or local
UNOLS regional or local
8 (one time)
0.5/yr
4-8/yr
5 (one time)
2 (one time)
5/yr
1/yr
ROV not needed if acoustically-
linked
10 (one time) ROV needed for installation of
junction box/seafloor sensors
5 (one time)
10/yr
10/yr
ROV needed for installation of
junction box/seafloor sensors
ROV required for servicing or
installation of seafloor sensors
ROV not required for acoustically-
linked moorings
5 (one time) Assumes 3700 km of cable (12%
buried)
ROV needed; probably carried out
over 2 field seasons
Stand-by maintenance contract
with industry
ROV needed; work may be limited
to May-Sept in Northeast Pacific
2 Pioneer Arrays; ROV not
required
Assumes one cabled observatory
2 Pioneer Arrays; ROV not
required
Divers or ROV (in deeper water)
required
bandwidth
rovings,
d at all
install
series sites.
ed for
p, 2000;
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ENABLING OCEAN RESEARCH IN THE 2 lST CENTURY
FIGURE 5-1 Photo of the Midnight Arrow, an offshore energy industry Class 2
sub-sea construction vessel. Vessels like this with a heavy lift capacity, large load
capacity, and ample deck space would be ideally suited for deploying large spar
buoys and moorings and seafloor node installation, maintenance, and replace-
ment. Figure courtesy of Torch Offshore, Inc.
Operation and Maintenance Ship Requirements
The open-ocean moorings that are part of the global observatory net-
work will require significant large-ship and deep-ocean ROV time for
maintenance. Annual maintenance will be required for surface moorings
due to biofouling, sea air corrosion, battery replacement, diesel refueling,
and buoy turn-around. Routine maintenance of both the low-bandwidth
and high-bandwidth moorings can be accomplished using a large, global-
class UNOLS vessel, so long as the necessary maintenance does not in-
clude recovery of a large spar buoy. Mechanical components, electronics,
and even diesel generators for the high-bandwidth systems can be de-
signed for servicing or replacement at sea using standard UNOLS winches
and cranes. If a large spar buoy must be replaced, a commercial workboat
or heavy-lift vessel will be required. EOM cable-linked moorings with
seafloor junction boxes will require dynamic positioning and a deep-ocean
ROV to service or install instrumentation. Fatigue considerations, espe-
cially for the high-latitude or other severe environment sites, will require
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RELATED FAC/~/TY NEEDS FOR AN OCEAN OBSERVATORIES NETWORK 143
periodic refurbishing or replacement of the moorings, while routine re-
placement/refurbishment of buoys will likely be necessary about every
three to five years. Approximately one month of ship time per node (in-
cluding transits to and from the site) should be anticipated for mainte-
nance of the remote global network sites. Coastal moorings will also re-
quire regular servicing, probably at least quarterly, by a small- or
intermediate-class UNOLS vessel or the commercial equivalent. Two days
of ship time annually per mooring (a conservative estimate) will be re-
quired for coastal mooring maintenance.
One special requirement of moored buoy maintenance is the lack of
flexibility in ship scheduling. Due to limited battery life and fuel avail-
ability and the need to replace biofouled and weathered sensors, ship
visits to a select site will need to occur regularly (approximately once
every 12 months) with little leeway (within a two week period). This
requirement, together with the remote locations of many of the global
observatory sites and small operational weather windows at high lati-
tudes, introduces a powerful constraint on the UNOLS ship scheduling
process, especially if between 15 and 20 sites distributed across all of the
major ocean basins must be visited annually. Ship scheduling will also be
complicated by observatory failures that require emergency repair and by
repair of failures in remote locations during severe weather months, both
of which will likely involve significant delays. On the positive side, peri-
odic visits to remote sites in the ocean will provide an opportunity for
other science efforts to study regions that would otherwise seldom be
visited. It should be noted that coastal moorings do not suffer from this
problem due to their much greater accessibility.
Cabled Observatories
Installation Ship Requirements
Installation of cabled observatory systems will employ both industry
and UNOLS vessels and will require detailed pre-installation cable route
surveys using high-resolution seafloor mapping systems and bottom sam-
pling. In addition, the amount of survey time needed depends on the
length of the cable route and the need for near-bottom and surface map-
ping. These requirements can be met using existing UNOLS assets, al-
though they could also be contracted through industry. A commercial
cable-laying ship (Figure 5-2) will be required to install the backbone fiber
optic cable and bury it where necessary (under 2000 m water depth).
Plans for the proposed NEPTUNE system, estimate that 159 days (ap-
proximately 5 months) of ship time are needed to lay approximately 3700
km of cable, including post-lay inspection and burial (B. Howe, Univer-
OCR for page 144
[~NC OCEAN ~~C~ /N [~[ 2 /~r CANNY
FICURE 5-2 Photo of Me Cable Refrfe~er, ~ state-oFthe-art purpose-designed,
at/-stern working cable ship, equipped gin an ROV (~D view top; rear view
bottom). This 117 m long vessel has ~ storage capacHy of some 2,475 tons of cable.
Specified vessels such as this fig be required for observatory cable instaUation
and repay. Figure courtesy of global Marine Systems Limited.
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RELATED FAC/~/TY NEEDS FOR AN OCEAN OBSERVATORIES NETWORK 145
sity of Washington, personal communication, 2003~. Installation of cabled
systems with loops and branches may require the use of two cable ships.
If installation is phased, this work could be divided over two field sea-
sons. Subsequent node, core instrument, and community instrument in-
stallation can be achieved using a large UNOLS vessel equipped with
dynamic positioning and an ROV. Assuming one week of ship time per
node (about two days for node installation and five days for sensor instal-
lation), approximately eight months of ship time would be required to
install a 30-node network like NEPTUNE, including transits. Given
weather constraints in the Northeast Pacific, this work would probably be
done over two successive field seasons.
Requirements for installation of cables for coastal observatories are
similar to those described above, although all cables will need to be bur-
ied. Node and instrument installation can be accomplished by smaller
UNOLS vessels, and in shallow water, by divers.
At global sites that prove feasible for re-use of retired telecommunica-
tion cables, a large UNOLS vessel or commercial cable vessel can be used
to retrieve the cable, cut it, and install a termination frame and junction
box. An ROV will be required for installation and the vessel must possess
dynamic positioning capability. At most sites it should be possible to
complete the basic installation with one month of ship time per node,
though additional ship time will be required for installation of sensors or
ancillary observing systems (e.g., a surface or sub-surface mooring).
Operation and Maintenance Ship Requirements
Standard submarine telecommunications cables are engineered for
extremely high reliability; the main risk to these systems is damage or
cutting from fishing activity. While failures of the backbone cable are
expected to be uncommon, a stand-by maintenance contract with a cable
company will be needed to repair cable breaks since these repairs cannot
be done with a UNOLS vessel.
It is expected that regular service will be required for both network
nodes and sensors. The NEPTUNE Feasibility Study (2000) budgeted four
months per year for regular annual maintenance of its proposed 30-node
system (one month per year for node maintenance; three months per year
for instrument servicing). At H20, however, only two experiments have
been deployed but more than one month of ROV time on site has been
used in five years; such a rate suggests that at least one week of ROV on-
site time may be required annually per observatory node for node and
instrument service about eight months per year for a 30-node system.
This work can be completed using a standard large UNOLS vessel (or
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146
ENABLING OCEAN RESEARCH IN THE 2 lST CENTURY
commercial equivalent) equipped with dynamic positioning and a deep-
ocean ROV. Weather conditions and the sea state limitations of current-
generation ROVs will likely limit these operations to the summer months
in the Northeast Pacific, and could require two ROV-equipped vessels
each season. Maintenance of shallow-water, coastal, cabled observatories
can be accomplished from local or regional class UNOLS vessels using
divers; though an ROV will be required in deeper water.
The University National Laboratory System Capabilities and Research
Observatory Requirements
While Table 5-1 is, at best, a rough estimate of the ship time require-
ments associated with the installation and maintenance of the observato-
ries that will be acquired as part of the OOI, it illustrates the very signifi-
cant demands ocean observatories will place on the UNOLS fleet. The
installation of 15-20 global observatory sites, a regional NEPTUNE-like
cabled observatory, and coastal observatories consisting of both moor-
ings and cabled sites is likely to require over four ship-years (assuming
300 operational days per year) including 1 ship-year on industry contract
vessels (for both cable laying and spar buoy installation). Maintenance of
this infrastructure will require at least an additional three ship-years an-
nually. These estimates do not include ship time requirements for obser-
vatory-related science beyond those required for installation and mainte-
nance of the basic infrastructure, and core and community experiments.
That figure, though hard to estimate, could conceivably be another one or
two ship-years or more per year.
It will be difficult for the UNOLS fleet to support the demands of
research observatories while still adequately meeting the need for more
traditional ship-based expeditionary research by the academic commu-
nity. Open-ocean observatory operations require ships with (1) ample
deck space and winches capable of handling large loads for mooring and
seafloor node installation or replacement, (2) the endurance to operate in
remote areas of the world's oceans and at high-latitudes, and (3) the ca-
pacity to accommodate relatively large numbers of scientists and engi-
neers. Except when servicing low-bandwidth, acoustically-linked moor-
ings, such observatory operations will also require dynamic positioning
capability and the ability to operate a deep-ocean ROV. The only UNOLS
vessels with these capabilities are the large (70-90 m long) global-class
vessels (Thompson, Revelle, Melville, Atlantis, and Knorr). Atlantis, how-
ever, is more or less dedicated to manned submersible operations and all
of the other vessels in this class are currently heavily subscribed for expe-
ditionary research. It is thus unclear how the UNOLS fleet can meet the
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RELATED FAC/~/TY NEEDS FOR AN OCEAN OBSERVATORIES NETWORK 147
ship demands outlined in Table 5-1 for ocean observatory installation and
operation without having a major negative impact on the availability of
these ships for other research. For example, 3 ship-years of global-class
vessel time would require that the Thompson, Revelle, and either Knorr or
Melville be completely dedicated to observatory operations each year.
This problem will be exacerbated if NOAA increases its utilization of
UNOLS global-class ships as the IOOS is established or if the proposed
Ocean Exploration Program moves forward. Since the demand for these
ships for expeditionary research is expected to remain high, the increased
need for large vessels by ocean observatories will have to be met, at least
in part, either by adding new vessels to the UNOLS fleet or leasing com-
parable vessels on the commercial market. Coastal observatories face less
pressure on available vessels, as the present small- and intermediate-class
UNOLS vessels can support coastal observatories. In addition, the ship
time requirements are not as large as for open-ocean observatories (Table
5-1), and this vessel class is presently somewhat underutilized, so it should
be able to accommodate increases in ship time demand.
The NOPP's Federal Oceanographic Facilities Committee (FOFC) has
developed a plan for renewal of the U.S. national academic research fleet
over the next two decades (Federal Oceanographic Facilities Committee,
2001~. This plan calls for no new global-class vessels in the UNOLS fleet
until 2018, but the addition of six new "ocean-class" vessels between 2002
and 2016. Although smaller than global-class vessels, this new vessel class
is expected to encompass some of the capabilities of both the intermedi-
ate- and global-class vessels in the UNOLS fleet today (Federal Oceano-
graphic Facilities Committee, 2001~. In addition, ocean-class vessels will
be designed to support ROVs and some will be capable of operating at
high-latitudes and at ice-margins. The first of these new ocean-class ves-
sels, the Kilo Moana, began service in 2002. The Kilo Moana is a Small
Water-plane Area Twin Hull (SWATH) vessel that allows for better heavy-
weather performance than similarly-sized conventional monohull ships.
However, the SWATH design may not achieve ocean observatory re-
quirements for heavy lifting and mooring deployment.
The present UNOLS Fleet Renewal Plan does not adequately address
the ship requirements of the ocean research observatories that will be
acquired through the OOI. Ocean observatory science will not reduce the
need for ships (overall ship usage will actually increase) but the kinds of
ships needed will change. Open-ocean observatories will require ships
with larger decks, heavy-lifting winches, and dynamic positioning and
ROV capabilities, that will need to operate in remote ocean areas and at
higher sea states than present ships. It is not clear how well the new
ocean-class vessels in the UNOLS Fleet Renewal Plan will meet these
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ENABLING OCEAN RESEARCH IN THE 2 lST CENTURY
requirements for open-ocean observatories. Furthermore, no funding has
been identified for these new vessels; given the long lead time for acquir-
ing new vessels, the first of these vessels will probably enter the fleet late
this decade, at the earliest. Within UNOLS, this leaves open-ocean obser-
vatory operations dependent on the existing five, already heavily sub-
scribed global-class UNOLS vessels, two of which are slated to be retired
(without replacement) in the middle of the next decade. Such a scenario
will not be adequate to both meet the ocean observatory ship time re-
quirements outlined in Table 5-1, and still support other research needs in
the oceanographic community. This problem will become critical as the
installation of these observatory systems begins in 2007 or 2008. The long
lead-time in acquiring new vessels means that this problem requires the
immediate attention of FOFC, UNOLS, and the NSF.
One option that should be investigated is the acquisition of a large,
heavy-lift (20,000 lbs) vessel by UNOLS for use in mooring and seafloor
node installation, maintenance, and replacement. These vessels are readily
available new or used, for lease or purchase, from both the offshore en-
ergy industry and the submarine telecommunications industry (Figure 5-
1~. The availability and cost of a commercial vessel will be a function of
the overall economy and the state of those particular industries. These
market-driven variations can be quite large, making short-term leases
somewhat unattractive. A longer-term lease (5 or 10 years), however, can
protect against these market swings, a situation that has worked very
well for the ODP. Alternatively, a vessel could be purchased and oper-
ated by a UNOLS member institution, an approach that has been used by
UNOLS for acquiring a multi-channel seismic vessel for use by the aca-
demic community. The advantage of either a long-term lease or outright
purchase is that scheduling would be under the control of the academic
community, not industry. Such a vessel could also be specially outfitted
for use as a research platform and could, in combination with the existing
UNOLS global-class vessels, begin to meet the large ship needs of both
observatory and expeditionary science until the beginning of the next
decade. Over the longer-term, however, UNOLS will require additional
observatory-capable vessels, obtained through either lease or purchase, to
meet the requirements of ocean observatory science.
DEEP SUBMERGENCE ASSETS
ROVs will likely be the work-horses of deep-ocean observatories, as
such resources will be needed for installation of seafloor observatories,
connecting moorings to seafloor junction boxes, installing experiments,
and servicing or repairing instruments and network equipment on the
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RELATED FAC/~/TY NEEDS FOR AN OCEAN OBSERVATORIES NETWORK 149
seafloor. ROVs' durability on the ocean bottom, heavy-lift capability, and
high available power make them indispensable assets for observatory
operations.
ROV technology has been advancing rapidly, both within industry
and within the oceanographic research community, and systems are now
available that can meet most ocean observatory requirements. Even more
capable ROVs can be expected to be available in the future. There are
several hundred ROVs available commercially, and systems have been
designed for a variety of missions (search and recovery, inspections, cable
laying, surveying, and underwater construction) at which they are ex-
tremely capable (see following section). Most ROVs used in the offshore
energy business are designed for use in relatively shallow water, but
some now operate in depths up to 3,000 m. The U.S. oceanographic re-
search community is now also routinely using a small number of ROVs.
The Jason II, available through the U.S. National Deep Submergence Facil-
ity (NDSF), can work at depths of up to 6,500 m (Figure 5-3~. MBARI
operates two ROVs: Ventana, rated to depths of 1,830 m, and Tiburon,
which can work in depths of up to 4,000 m. Ventana's operations, how-
ever, are generally limited to Monterey Bay and Tiburon's to the U.S. West
Coast; neither of these ROVs are part of the U.S. National Deep Submer-
gence Facility. The Canadian Remotely Operated Platform for Ocean Sci-
ence (ROPOS), which is rated to 5,000 m depth, is also sometimes avail-
able to researchers working in the Northeast Pacific.
Two important operational considerations for ROV use in the context
of ocean observatories are water depth and sea state. Many sites for both
global and regional observatories are in water depths greater than 3,000
m, making many of the hundreds of commercial ROVs unsuitable for use.
There are a comparatively small number of deep-ocean ROVs, available
either commercially or within the U.S. academic community, capable of
operating in water depths of up to 6,000 m, although this situation may
change rapidly in the next few years as the energy industry moves into
deeper and deeper water. The ROVs used by the academic community,
such as Jason II, are generally limited to operations in sea states less than
4. This restriction will significantly limit operations in winter months at
many locations (e.g., the Northeast Pacific) and over much of the year at
some high-latitude sites. Some industry ships and ROVs can operate in
sea states as high as 7. Upgrading the dynamic positioning systems and
ROVs used on large UNOLS vessels to operate at higher sea states would
significantly expand the operational window at many observatory sites.
Table 5-1 provides an estimate of ROV time requirements for install-
ing and operating OOI global, regional and coastal observatories. Ten to
fifteen ship-months of ROV time could be required for installation of the
global observatories and up to eight ship-months for a large, regional
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ENABLING OCEAN RESEARCH IN THE 21ST CENTURY
FIGURE 5-3 ROVs like the fason II (above), will be the work-horses of ocean
observatories. ROVs will be needed for installation of seafloor observatories,
connecting moorings to seafloor junction boxes, installing experiments, and ser-
vicing or repairing instruments and network equipment on the seafloor. Jason II
was designed for detailed survey and sampling tasks that require a high degree
of maneuverability. Jason II is operated by the U.S. National Deep Submergence
Laboratory at WHOI. Figure courtesy of (redwoods Hole Oceanographic Institu-
tion.
cabled observatory. Comparable amounts of ROV time will be required
annually (about two ship years) to meet operations and maintenance re-
quirements of these ocean observatories. Most observatory sites will re-
quire deep-ocean ROVs (rated to depths over 3,000 m). Due to the short
weather window in the Northeast Pacific, a large cabled observatory like
NEPTUNE may require two ROVs operating each summer in order to
service the system.
A single deep-ocean ROV, Jason II, as the only ROV available through
the U.S. National Deep Submergence Facility will clearly be inadequate
for both observatory and general science support. The availability of more
ROV assets is imperative if observatories are to be fully utilized. Table 5-1
suggests that two deep-ocean ROVs largely dedicated to ocean observa-
tory work will be required by 2008 or 2009, when installation of the high-
bandwidth global and regional cabled observatories begins. The addition
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RELATED FAC/~/TY NEEDS FOR AN OCEAN OBSERVATORIES NETWORK 151
of a second ROV to the U.S. National Deep Submergence Facility, along
with seasonal use of ROPOS in the Northeast Pacific, would begin to
provide the needed deep-ocean ROV assets. In the longer-term, however,
a third ROV will probably be required in UNOLS to fully meet both
expeditionary and observatory research requirements. One or more of
these ROVs should be work class, and possess numerous hydraulic
outputs and controls for tools for routine observatory maintenance and
. .
servlcmg.
Human-occupied vehicles (HOVs) are not likely to play a major role
in routine observatory installation and servicing due to their lack of
power, short dive duration, lack of heavy-lift capability, avoidance of
suspended cables, and limited vessel-to-surface communication capabili-
ties. However, because HOVs are not tethered to the surface (making
them highly maneuverable), they may be useful in some instances for
conducting scientific investigations around observatory sites and for ini-
tially establishing experiments and locating sensors in areas of complex
topography (e.g., a hydrothermal vent field).
MAI NTE NANCE AN D CALI B RATI ON OF I NSTRUME NTATI ON
The OOI will enable cutting edge science at new and remote locations
in the world's oceans using many sensors, some specifically developed to
take advantage of the OOI. The full potential of these new measurement
capabilities can only be met if the infrastructure exists to service and
maintain observatory instrumentation and to conduct the routine calibra-
tion of sensors and instrument systems needed to document and ensure
their accuracy. Such work is essential to establish the quality and compa-
rability of OOI observations.
Instruments deployed at sea for up to 12 months, as envisioned for
the OOI, may require extensive maintenance. Calibration requires proper
facilities, including calibration standards, baths, and chambers, as well as
considerable staff support. In recent years, the number of U.S. groups
engaged in deploying moorings and maintaining moored instrumenta-
tion has decreased in number and the size of many of the groups that
remain has decreased. OOI planning should consider the staff and facili-
ties needs for the repeating cycle of pre-deployment instrument prepara-
tion and calibration, deployment, and post-deployment calibration and
servicing associated with the core and community instrumentation envi-
sioned for the OOI. For instrumentation that is labor intensive to service
and calibrate, costs for each cycle can approach the cost of acquiring the
hardware. The certification and maintenance of calibration infrastructure
can also be a significant ongoing cost.
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ENABLING OCEAN RESEARCH IN THE 21ST CENTURY
OTHER ENABLING TECHNOLOGIES
The first satellite-borne ocean sensing systems quickly revealed that
ship-borne oceanographic measurements are aliased to varying degrees
of severity by temporal variability in ocean processes. If ocean observato-
ries are not to repeat this history with spatial (rather than temporal)
aliasing, it is essential to acknowledgefrom the outset that time-series from
fixed locations in the ocean can provide temporally and vertically well-
resolved measurements but that these measurements cannot be properly
interpreted without accompanying information on horizontal spatial vari-
ability. It is thus essential to develop and use sampling strategies that
enlarge the footprint of observatory sites in order to provide spatial infor-
mation at a resolution sufficient to separate advective (spatial) changes
from true temporal changes. Since the appropriate horizontal resolution
will vary depending on the specific processes being addressed at a par-
ticular observatory node, the most cost-effective mechanism for provid-
ing this information will also vary. Using secondary moorings attached to
a primary cabled node may be sufficient for some sites and processes.
Others will require more widely-spaced, fixed sites, communicating with
an under-sea node by acoustic telemetry. Still others may require more
flexible mapping operations, in which multiple gliders or AUVs are
directed in real-time.
Significant advances have been made in underwater acoustic telem-
etry in recent years, making this a promising technology for extending the
reach of individual observatory nodes. Instruments equipped with acous-
tic modems on subsurface moorings or on the seafloor within several
kilometers of an observatory node can be linked acoustically to the node
without the expense of laying additional cable. Data can also be transmit-
ted acoustically from an underwater vehicle to a receiver located two to
three km distant, potentially allowing real-time control of an AUV during
a survey. The newest generation acoustic modems use high-bandwidth,
phase-coherent communication and directional transducers and can pro-
vide data throughputs of up to 5 kb/s (with error checking) (Freitag et al.,
2000~. Continued support of underwater acoustic telemetry development
should provide increasing range, bandwidth, and reliability for these sys-
tems.
There has been much interest in the use of AUVs to extend the foot-
print of observatories well beyond that possible by cables or acoustic
links (Figure 5-4~. Possible AUV missions might include:
· repeat high-resolution seafloor or geophysical mapping to identify
changes related to geological activity;
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FIGURE 5-4 WHOI's Autonomous Benthic Explorer (ABE) is one of a growing
number of AUVs being developed in industry and academia. This technology is
still in the early stages of development and a number of important issues remain
before AUVs are routinely used at ocean observatories. However, the base of
technology and expertise in AUVs is growing at an accelerating rate and they are
likely to play an increasingly important role in observatory science by the end of
this decade. Figure courtesy of (a) Woods Hole Oceanographic Institution.
· water column mapping to determine variations in physical or
chemical properties in a volume of ocean around an observatory node;
· measurement of fluxes; and
· response to transient events detected by observatory monitoring.
AUV technology is still in its infancy and not yet ready for observa-
tory applications. Docking for data retrieval, obtaining commands, and
transferring power are not yet routine. Problems related to operating
reliably for long periods without maintenance also need to be solved
before AUV support of observatories will become a reality. However, the
U.S. Navy and the offshore energy industry have shown a growing inter-
est in AUVs and the base of AUV technology and expertise is growing at
an accelerating rate. By the end of this decade, when these research obser-
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vatories are fully operational, it is likely that AUVs will be playing an
increasingly important role in observatory science and operations.
Gliders (an AUV with ballast tanks rather than propellers or motors)
are another emerging new technology for water column mapping (Eriksen
et al., 2001), although they are also in a developmental stage and the
process of devising control systems for deployments of multiple instru-
ments is just beginning. The observatories funded by the OOI will un-
doubtedly become testbeds for the development of the next generation of
AUV and glider technology. While these technologies are not crucial to
the installation phase of the OOI, they are likely to be important for real-
izing the full scientific potential of ocean observatories.
ROLE OF INDUSTRY IN OCEAN OBSERVATORIES
The energy and telecommunications industries can be involved in
many aspects of ocean observatories, from supplying the cables, buoys,
and instruments for observatory infrastructure to the ships, ROVs, and
support services needed to maintain and operate this infrastructure over
the long term. Since the academic community does not manufacture most
of the items necessary to build a seafloor observatory, industry will sup-
ply many of the components that comprise the infrastructure. Academic
institutions and various government agencies own or long-term lease
vessels, ROV systems, and other assets that could be used to install and
maintain observatories. Examples are the UNOLS fleet and ROV systems
like JASON II. This section describes the commercial resources that could
be used to install, operate, and maintain ocean observatories and the
potential role of industry in ocean observatory operations.
Vessels
More than 1,000 commercial vessels are engaged in the offshore en-
ergy business. A single company operates 188 vessels in U.S. waters and
an additional 327 internationally. Another large U.S. firm operates more
than 300 vessels, the older and smaller of which are typically 55 m long
with low and long back decks. Newer vessels range from 85-100 m long
and have much higher freeboard, and are powered by engines ranging
from 3,000 to more than 10,000 horsepower. While current missions in-
clude things as simple as delivering groceries to installing anchor piles in
2,100 m of water, commercial offshore supply boats or anchor handling
tug boats are ideally suited for launching or removing large spar buoys
and moorings and for seafloor node installation and replacement. As
noted above, UNOLS should consider acquiring a heavy-lift workboat for
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observatory operations, either through outright purchase or through a
long-term, multi-year lease.
The offshore telecommunications industry employs an additional fleet
of cable-laying vessels, augmented by maintenance vessels very similar in
size and capability to the offshore energy vessels. The considerable expe-
rience of these cable-laying companies represents a valuable resource for
observatory design and installation. The academic community should
consider using these commercial vessels for installation and maintenance
of ocean observatories. A particular window of opportunity to negotiate
very favorable leasing agreements for cable-laying vessels will exist for at
least the next few years given the depressed state of the telecommunica-
tions industry.
Buoys and Floating Platforms
The offshore energy industry has years of experience in building and
operating large, moored platforms, often in very hostile environments. As
the oceanographic community begins to consider acquiring large moored
buoys, it will benefit from tapping into that experience. Although the
smaller buoys currently in use by the academic community are typically
built in-house, the larger systems under consideration should be designed
and built commercially. One company (Maritime Communication Ser-
vices, a division of Harris Electronics Systems) offers a commercial
moored buoy system known as OceanNet that is designed for high-band-
width, high-power applications. This system consists of a large 5.2 m
discus buoy equipped with diesel generators, a 2 Mb/s C-Band satellite
telemetry system, and a fiber-optic riser cable connected to a seafloor
junction box. This complete "turn-key" system, including operation and
maintenance, can be leased on a long-term basis. As the market for ocean
observatories grows, other similar systems may become available. The
cost-effectiveness of commercially leasing observatory systems should be
thoroughly evaluated as part of the development of an observatory imple-
mentation plan.
Underwater Assets:
Remotely Operated Vehicles and Autonomous Underwater Vehicles
ROVs have served as productive tools in the offshore energy and
telecommunications industries and the military for more than a quarter of
a century. Due to the physiological limitations of the human body at great
depths and the practical limitations of cost effectively deploying manned
submersibles, working beyond the world's continental shelves would not
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be economically feasible without ROV systems and, to an increasing ex-
tent, AUVs.
Hundreds of work-class ROV systems are in operation worldwide in
both the offshore energy and telecommunications industries. Six major
contractors engaged in the offshore energy business operate over 80 per-
cent of these ROVs; most of the remaining systems serve industry in the
hands of smaller companies. Many specific task systems, such as mine
hunting, are deployed by the military and a few thousand smaller obser-
vation or inspection class systems are in use in lakes, rivers, and coastal
areas. The work-class systems range in size from that of a sub-compact
car to a dump truck. As much as 750 hp is available in propulsion through
multiple thrusters, with typical power in the 100 hp range. Many systems
are capable of operating in depths of up to 3,000 m.
Sensors and tools include multiple digital color video cameras, high-
resolution sonar, and many job specific tools, sensors, and data collectors.
Payloads of 1,000 lbs are not uncommon, with some systems capable of
1,600 lbs of vertical thrust. Manipulators are strong enough to lift more
than 200 lbs and dexterous enough to tie a knot in a piece of rope.
AUVs have been in use by the military and the scientific community
and are being introduced to the offshore industry for use as survey tools.
These devices now carry sensors, such as sonar and video, but have no
ability to perform work tasks. They will evolve as did the ROV and
will become essential tools of the future. This evolution will include step
changes, such as hybrid systems and parking garages on sub-sea produc-
tion facilities.
Manned submersibles are in very limited use in the offshore industry.
Given the capabilities of present work class ROVs and today's optical and
sensor technology, the offshore industry does not see manned submers-
ible as a cost-effective or efficient tool for their needs. More than 50 years
of offshore (energy) vessel operations and a quarter of a century of ROV
experience is available from industry, which learned hard lessons at great
cost, not to taxpayers, but to corporations and individuals during the
industry's evolution into the safe and efficient community of today. Those
lessons fueled the development of the ROV and are going to take those
systems to another level as ROV/AUV hybrids and, ultimately, true AUV
systems are developed. Vessel operations efficiency and safety records
are outstanding in the offshore energy business. All in all, the ocean re-
search community would be wise to draw on this hard-earned experi-
ence.
Representative terms from entire chapter:
ship time
