Geoscience Reference
In-Depth Information
communications, or taut-line surface moorings before the transfer of operations from PMEL. The
committee's assessment revealed problems that reduced the effectiveness of the technology
transfer from PMEL to NDBC, including a lack of training of NDBC personnel on DART deploy-
ment methods, a preference for NDBC mooring deployment procedures that conlict with
PMEL's recommended deployment procedures for the DART stations, and a lack of coordination
of post-transition research activities. These observations are consistent with other issues raised
in a report by the Inspector General of the Department of Commerce about the need to make
improvements to some of NDBC's buoy maintenance operations (U.S. Department of Commerce
Ofice of Inspector General, 2008). The report found that technology transfers from PMEL to
NDBC have not been well coordinated and planned, and it offered several recommendations to
address these concerns, such as ensuring that data requirements and technical speciications
are clearly deined prior to the transition and that adequate funding is available to cover the
transition costs. The report also recommends better coordination on research and development
projects between the two NOAA centers to avoid duplication of efforts.
DART II failure modes cut across the suite of components in the DART II stations, such
as bottom pressure sensor faults; acoustic transducer failures; tilt sensor failures; CPU, acous-
tic modem, and interface board failures on both the BPR and buoys; and mooring hardware
failures. By far the most common problem is mooring hardware failure. For example, of the 12
DART II stations listed as inoperative on May 11, 2009, 8 were listed as “adrift.” In other words,
the mooring line holding the surface buoy had parted so that the surface buoy had drifted
away from the location of the BPR. Although NDBC has an active failure analysis program, this
program needs improvement; for instance, when a buoy goes “adrift,” neither it nor the moor-
ing remnants left on site are presently recovered by NDBC, so that the cause of the mooring
line failure, or other failure mode, remains undetermined. There are many possible causes for
mooring line and buoy failures, such as faulty components, improperly assembled moorings,
physical interference from “long-line” ishing activity, ish bite, vessel collisions resulting in buoy
sinking, vandalism, extreme environmental conditions, metal fatigue, high currents towing the
buoy under water, and improper mooring scope on deployment due to error in water depth
determination and/or mooring line measurements (an allowable error is 1.5 percent or less).
In response to these problems, NDBC held a mooring workshop in February 2010 with partici-
pants from Woods Hole Oceanographic Institution (WHOI), PMEL, SIO, Science Applications In-
ternational Corporation (SAIC), and other agencies and institutions. A broad spectrum of topics
was addressed, and speciic issues affecting DART reliability were identiied and summarized
for NDBC management.
A principal objective of NDBC's effort to improve DART reliability is to reduce ship time
costs. A system that requires unanticipated maintenance visits using costly ship time reduces
availability of funds for other activities.
The committee analyzed the beneits and disadvantages inherent in each of these main-
tenance approaches. In order to maintain the current DART network coniguration, adequate
resources are needed for maintenance, including funding for unscheduled ship time to effect
repair and replacement of inoperable DART stations. The alternative approach would be to
invest the majority of resources into improving the DART station reliability to get closer to the
