New SAR Initiatives Fund (NIF)

Final Summary Report 2009-2010

Self-Locating Data Marker Buoy (SLDMB)

Self Locating Data Marker Buoy [PDF 254Kb]

Project Number/NIFID:

DFO 3/08 NIF ID 2007010 Project Code: MSS67

Financial Summary:

Total Project Cost $986,649.00

Project Description:

Search and Rescue (SAR) agencies, such as the Canadian Coast Guard (CCG), use vessel and air-deployed self locating datum marker buoys (SLDMBs) to aid in predicting the drift of SAR objects, and to reduce overall search time and effort. The SLDMB achieves this by emulating an object in the water and communicating its GPS position, via satellite, to a Rescue Coordination Centre’s search planning software.

Previously, SLDMBs have been subject to two main deficiencies:

  • A reliance on the ARGOS satellite system for data telemetry, resulting in long and variable latencies in message arrival;
  • SLDMBs approved for use in Canada are configured to render the total water current (TWC) and leeway drift (or wind-driven) components as an aggregate, whereas the CCG SAR drift models are more accurate when ingesting only the TWC component.

This project considered the development of a new-generation SLDMB in a TWC configuration with low-latency Iridium satellite communications. Further, this buoy would be physically confined to an “A-Size” form factor to facilitate compatibility with existing release systems aboard CCG and Department of National Defence (DND) airborne assets.

The project was carried out over a period of 28 months ending in March, 2011. C-CORE did not develop hardware, but instead solicited the participation of existing commercial manufacturers to develop and construct prototypes, which C-CORE tested, in an independent un-biased capacity. CCG also identified a need for a web-hosted application to handle operational aspects of the new-generation SLDMB. C-CORE, having the capacity to develop such software, undertook this development through a contractual change of scope, producing a functional product by project end.

Proposal Objectives:

The objectives as defined by the original proposal were amended part way through the project, under the direction and authority of the project Technical Authority. This amendment replaced all efforts associated with drift characterization (i.e., slip studies) with the development of a web application suite (SLDMB WAS), providing operational support for the new generation SLDMB;

The project objectives described below are those reflected by this amendment:

  • Conduct a literature search of relevant drifter models to help identify applicable designs and to ascertain which of these might be best suited to a TWC representation in this specific application;
  • Identify at least two different SLDMB designs, preferably from different manufacturers, to carry through the testing phase;
  • Execute a SLDMB development program that produces a new SLDMB design primarily intended to integrate a TWC drift capability and two-way satellite communications within a package similar to or smaller than an A-size package;
  • Procure, from manufacturing subcontractors, a quantity of engineering prototypes, in excess of five for each design, constructed to facilitate environmental testing, air launch testing and vessel deployment testing/demonstration.
  • Investigate systems and/or develop software modules that provide operational support for the next generation SLDMB, as follows:
    1. CANSARP Pre-loader: CANSARP formerly ingested SLDMB data acquired from ARGOS; a pre-loader module will be implemented to provide compatibility with Iridium messages delivered by the next generation SLDMB;
    2. Web Interface: A web interface will be developed to provide a live mapping of SLDMB coordinates and an associated history of positions. As Iridium allows two-way communications, the web-interface will also provide a utility to exercise command over the buoy (e.g., shut-down);
    3. Surface Current Mapping: Existing models for converting SLDMB positional data into vector current fields will be investigated. Further investigation into implementing such models in an operational sense will be carried out. Any implementation will be contingent upon the investigation results;
    4. Position Hindcasting and Forecasting: Existing practices for hindcasting and forecasting SLDMB positions based on an available time series of real positional data will be investigated. Means of enhancing and automating such practices within the context of SLDMB software environments will be recommended. Any implementation will be contingent upon the investigation results;
    5. CANSARP High Resolution Data: CANSARP has a deficiency in its ability to ingest high-resolution current field data. Measures to improve CANSARP in this respect will be investigated, and recommendations will be made for relevant upgrades to CANSARP. Any implementation will be contingent upon the investigation results.
  • Execute an environmental testing program comprising pressure, temperature, vibration and acceleration, and others as identified;
  • Execute a vessel deployment testing program with the engineering prototypes;
  • Execute an air deployment testing program with the engineering prototypes;
  • Recommend contractor-of-choice for further collaboration in the manufacture of next generation SLDMBs defined by this project.


The outcomes achieved with respect to the objectives enumerated in the previous section are described below. In each case, associated benefits to the SLDMB stakeholders are described. The recommendations alluded to in objective 9 are deferred to the Evaluation section of this report.

Literature Search

The literature search comprised a review of relevant literature on the subject of drifter design and performance, complemented by meetings with key researchers, relevant Canadian and US government authorities, and manufacturers, to assess the state of the art in drifter technology, and garner an understanding of which drifter models are most relevant to SAR operations. Relevant papers are listed in the Bibliography Reference section of this report.

This research presented two relevant drifter models—the Code (or Davis) drifter, and the Tri-Star drifter. The Code drifter has been used in previous generation SLDMBs; however, the Tri-Star has only seen application in studying surface currents. Both the Code and the Tri-Star are TWC designs, and are depicted in Figure 1.

The Code drifter comprises four orthogonal vanes suspended vertically in the water column—each suspended from a surface float and attached to a tubular structure at the center of the assembly. The tubular structure typically houses any support electronics and batteries, and if required, an antenna may extend from the top of the tube, some distance above the water surface. The Tri-Star drifter comprises an assembly of orthogonal vanes forming eight adjoining tetrahedrons, suspended from the surface by a single tether attached to a surface float. The surface float houses any support electronics and batteries, and if required, an antenna may be affixed at the top of, or within, the float. The distinguishing features of the Tri-Star are: the presence of horizontal vane sections; and, a single tether.

SLDMB - Code Drifter and tri-star drifter

Figure 1: Drifter Types

The research also lead to a deeper understanding of methods employed by the scientific community to understand how closely different drifter types follow the currents in which they are deployed. These methods characterize slippage, defined as the difference between the actual current in the layer under consideration and the observed velocity of the drifter.

Derived Benefits

  • An alternative to the Code drifter was identified for consideration as an SLDMB; and
  • Lines of communication were established between C-CORE and the United States Coast Guard (USCG), scientific authorities, and Government of Canada (CCG and DND) stakeholders.

Identification of Manufacturers:

Four manufacturers were identified with the capacity to produce either of the two drifter types identified above. Of these, three expressed an interest in participating in the development of the new generation SLDMB. MetOcean Data Systems and Clearwater Instruments would develop a Code type buoy, and Pacific Gyre would develop a Tri-Star type buoy. All three manufacturers had previous experience in development and manufacture of the respective drifter types.

The three manufactures provided C-CORE with electronics-free prototypes for evaluation by C CORE in a wavetank and in the field. This evaluation revealed two notable problems with the Tri-Star design.

First, the antenna was very unstable in terms of maintaining a consistent attitude. Second, the float became submerged for a significant portion of the wave cycle (likely due to the horizontal vane sections). These problems both represent a significant risk in terms of the ability of this design to maintain reliable GPS reception and Iridium communications. Pacific Gyre was unable to make their design conform to the A-size requirement. For these reasons, the Tri-Star design was abandoned, leaving two manufactures, MetOcean and Clearwater, under further consideration in the project—both developing a Code-style drifter.

Derived Benefits:

  • Two viable manufacturers were identified and both agreed to participate in the project.

SLDMB Development:

The SLDMB development phase of this project was undertaken by the two manufacturers identified above. C-CORE facilitated the development phase in the following manners:

  • through communication with stakeholders, C-CORE developed and formalized the functional specification for the new-generation SLDMB;
  • C-CORE made arrangements with each manufacturer for the purchase of a quantity of SLDMB prototypes, and assumed responsibility for testing these prototypes;
  • through the execution of each testing phase, C-CORE communicated findings back to each manufacturer so that improvements to the designs could be effected prior to the next testing phase; and
  • C-CORE visited both facilities prior to issuing purchase orders for new SLDMB prototypes, and maintained steady communication with each manufacturer over the course of their respective developments to ensure the design was compliant with the functional specification.

Derived Benefits:

  • A new generation SLDMB functional specification.

Procurement of Prototypes:

C-CORE procured a total of 30 SLDMB prototypes from MetOcean, and a quantity of 18 SLDMB prototypes from Clearwater. These were acquired incrementally over the duration of the project to support the various testing phases. A summary of the buoy usage is presented in Table 1. Details of each test are further provided in this report.

Table 1: Buoy Usage Summary

Table 1 - Buoy Usage Summary
Test PhaseDateMetOcean
Environment Testing March 2010 6 6
Vessel Deployment #1 July 2010 6
Vessel Deployment #2 October 2010 6 2
Vessel Deployment #3 March 2011 6
Buoys supplied as an in-kind contribution
Air Cannon Testing October 2010 2 2
Tip Testing February 2011 n/a 2
Air Deployment #1 November 2010 16 6
Air Deployment #2 March 2011 12
Buoys supplied as an in-kind contribution
Total Procured 30 18

Derived Benefits:

The prototypes procured were essential to the execution of the test program.

SLDMB Web Application Suite Development:

The SLDMB Web Application Suite, or Web Portal, is a web-based information portal for viewing the positions and tracks of active and inactive Iridium-based marker buoys—notably SLDMBs and Marine Marker Buoys (MMBs). A complete description of the Portal is available through the Portal’s on-line help facility and the Software Requirements Specification. However, this section provides an overview of the major features of the Portal.

CANSARP Preloader:

CANSARP formerly ingested data from SLDMBs equipped with ARGOS telemetry. It was conceived that a pre-loader module would be required for CANSARP, to enable the ingestion of data from the new generation SLDMB. However, a more practical implementation resulted, comprising an FTP data upload in an “ARGOS-formatted text file,” already compatible with CANSARP. A stand-alone “Updater,” written in Java, was developed and deployed on the Windows™ server to carry out the following tasks:

  • check the email server inbox;
  • download new Iridium messages from the buoys;
  • parse the messages;
  • update the database; and
  • regenerate and upload the ARGOS-formatted text file.

Web Interface:

The Web Interface was designed to provide user interaction with the Portal’s database for the following purposes:

  • viewing, in either a graphical or tabular format, buoy data on a track-basis;
  • exporting buoy data;
  • managing users and associated permissions;
  • viewing errors;
  • configuring server parameters;
  • managing buoy ownership;
  • invalidating or re-validating specific data points;
  • automatic filtering of erroneous data;
  • exercising control over buoys (for those types that are controllable);
  • producing hind-casted and forecasted data based upon a specific track of data; and
  • producing surface current maps in netCDF and textual formats.

Figure 2 shows the graphical display of the Portal, rendering a real SLDMB track, south of the Burin Peninsula, Newfoundland and Labrador.

Figure 2: Web Portal Graphical Display

Web Portal

Surface Current Mapping (SCM):

C-CORE subcontracted Dr. Keith Thompson of Dalhousie University to provide Matlab™ code that renders current flow vectors in netCDF format based on a set of SLDMB tracks and their interaction with the world shoreline. This code was integrated within the Web Portal, and is invoked by either of two means. SCM jobs may be manually configured with assigned buoy identifiers, which will automatically generate a new netCDF map every one-half hour and upload this map to an FTP directory used by CANSARP. Or, a user may manually invoke a one-time SCM job, with links provided for the resulting netCDF and text files so that they can be downloaded and viewed on the user’s PC.

An update to the Portal is anticipated, following this project, whereby SCM jobs are automatically initiated upon the deployment of new buoys (more precisely, upon the receipt of data from new buoys). In this case, proximity criteria will be used to establish which buoys belong to which specific SCM jobs.

Position Prediction:

A position prediction algorithm was developed by C-CORE to replace earlier methods employed by the CCG. This new method is based on a weighted linear regression model, and is described in the document “SLDMB Position Prediction” (a deliverable to the CCG at project end). The model will provide up to five hind-casted and forecasted positions, based upon a track of data for a given buoy. The model is implemented in Matlab™, and integrated within the Web Portal, and can be invoked by either of two means. Predicted positions may be automatically generated for the purposes of display on the Web Portal, uploading to CANSARP, and ingestion by the SCM model. The number of predicted positions may be uniquely configured on a buoy-basis, from zero (i.e., disabled) to five. The prediction may also be invoked manually on a selected track, and results viewed on the Web Portal. This feature is useful, for example, for viewing historical data.

High Resolution Data:

CANSARP source code, made available to C-CORE for the purposes of investigating provisions for the ingestion of high resolution surface current data, could not be successfully built on the development environment provided by the CCG for this purpose. The technical authority decided that, due to the onerous nature of configuring a development environment for CANSARP that replicates that of the CCG College, this task should be abandoned in favour of other higher priority tasks.

Other Features:

Other features not explicitly defined in the Proposal Objectives of this report, but inherent in the Portal implementation, are described here.

Windows™ Server

During the early stages of development, the Portal was deployed on a commercial Linux-based host (eApps); however, certain features of the Portal—notably SCM and Position Prediction—could not be accommodated by Linux, so a switch to a Windows™ platform was necessary to implement these features. The Windows™ server is intended to be installed at the CCG College in Sydney, NS, pending internal approval. Until such a time, a partially featured Portal will remain available through eApps.


The Web Portal automatically performs filtering of erroneous data, based on the following criteria:

  • Position: data with obvious erroneous coordinates (e.g., lat/long of 0/0) are automatically invalidated;
  • Rate: data that render buoy velocities in excess of 12 knots are automatically invalidated.

Derived Benefits:

  • The Web Portal provides an integrated environment for managing buoys and buoy data that had not previously existed;
  • The Web Portal client may be used from any computer with access to the internet;
  • The Web Portal provides and integrates filtering, prediction and surface current map generation based upon SLDMB data. This capability was not available for earlier generation SLDMBs;
  • The Web Portal is compatible with the MMB, a surface drifter developed by C-CORE under a previous NIF-funded project (NIF ID 2005019). The Portal exercise two-way communications with the MMB, and thus facilitates control over the MMB in addition to data collection.

Environmental Testing:

Environmental testing on prototypes produced by MetOcean and Clearwater was carried out during the project. A portion of this testing—namely vibration, shock, temperature, and pressure— was subcontracted to Environmental Simulation Labs (ESL) in Dartmouth, NS. Test reports were delivered to C CORE by ESL, and are part of the project deliverable to the CCG. Six buoys were procured from each manufacture to facilitate testing at ESL. Air Cannon of both prototypes testing was subcontracted to Ultra Electronics in Dartmouth, NS. C-CORE executed pressure and tip-over testing of the Clearwater buoys. A brief summary of the tests and results are provided in Table 2. Pressure testing on the Clearwater buoy could not be accommodated at ESL due to scheduling, and therefore was executed in St. John’s by C-CORE.

Table 2: Environmental Testing Summary
Test DescriptionSpecification



Vibratrion Test As per 7054-STP-2 Two buoys tested. No failure identified. Two buoys tested. No failure identified.
Shock Test As per 7054-STP-2 Two buoys tested. Damage observed during Z-Axis shock tests. Two buoys tested. Damage observed during Z-Axis shock tests.
Low and High Temperature Test As per C-CORE SLDMB Test Plan R-09-087-660 Two buoys tested. No failure identified. No failure identified.Two buoys tested.
Pressure Test As per C-CORE SLDMB Test Plan R-09-087-660 No leakeage observed. No leakage observed.
Air Cannon As per C-CORE SLDMB Test Plan R-09-087-660 Two buoys tested. One buoy failed to deploy without agitation. One buoy deployed upside down. One buoy failed to establish successful Iridium communications following the test.

Two buoys tested. Both buoys exhibited problems with arms locking inplace and show dissolving tape. One buoy failed to establish successful Iridium communications followign the test.

Tip-Over As per C-CORE SLDMB Test Plan R-09-087-660 One buoy tested. No failure identified. One buoy tested. No failure identified.

Derived Benefits:

  • Environmental testing was successful in identifying critical issues with the prototypes, providing each manufacturer an opportunity to remedy design problems prior to field deployment activities.

Vessel Deployments:

A total of four vessel deployment exercises were conducted—each comprising differing varieties of buoy types. Some sea trials were supplemented by the release of buoy-types other than SLDMBs, for the purposes of comparison. These included: previous generation MetOcean SLDMBs, described as large Code-type drifters currently used by the USCG, but retrofitted with Iridium communicators; and, MMBs , which are surface drifters—a product of an earlier NIF-funded project executed by C-CORE (NIF ID 2005019). The first two deployments were conducted in Placentia Bay, near Burin, NL. The third deployment was conducted out of Halifax, NS. Another vessel deployment was conducted on the Grand Banks by Dr. Fraser Davidson, of the Department of Fisheries and Oceans (DFO), as part of an independent study involving a large variety of drifters and oceanographic instruments, and included a quantity of new-generation SLDBDs from both MetOcean and Clearwater. The study was not executed under the auspices of this project; however, the outcomes of this study do supplement the findings of this project, and are thus presented here. Each vessel deployment exercise is treated separately in the following subsections.

The primary objective of the vessel deployments was to test the newly developed SLDMB’s reliability and survivability in the ocean environment. The SLDMBs were deployed in close proximity to one another and allowed to drift until they expired. Environmental data, as well as position data from the SLDMBs were recorded for the duration of the tests. This data was used to analyze the performance and suitability of the buoys.

Vessel Deployment #1 – Placentia Bay, NL, July 13-14, 2011

This deployment exercise took place over a period of two days, comprising deployments #1A and #1B as summarized in Table 3 and Table 4 respectively.

Vessel Deployment #1A Summary

Near Mortier Rock, 47 01.286N 55 00.700W
CCGC W. Jackman
July 13, 2010
Sea State
1-2 m waves
SW 10 knots
Table 3: #1A Summary - Buoys
Buoy Types Quantity
MetOcean(New) 3
Clearwater 3
MetOcean(Old) 3
Total 9

Vessel Deployment #1B Summary

Near Mortier Rock, 47 01.286N 55 00.700W
CCGC W. Jackman
July 14, 2010
Sea State
>1 m waves
SW 10 knots
Table 4: #1B Summary - Bouys
Buoy Types Quantity
MetOcean(New) 3
Clearwater 3
MetOcean(Old) 3
Siemac ARGOS 1
Marine Marker Buoy 3
Total 13

A summary of observations for the new generation MetOcean buoys is provided in Table 5. These buoys exhibited the following problems:

Redundant GPS positions reported in consecutive short burst data (SBD) Iridium messages, resulting in intervals lacking new positional data.

Table 5: Observations for MetOcean Buoys - Vessel Deployment #1
IMEI Start Tx(GMT) Last Tx(GMT) Comment
300034013709970 13 Jul 2010 15:20:00 23 Jul 2010
10 day life
300034013708970 13 Jul 2010 15:30:00 21 Jul 2010 09:00:00 8 day life
300034013700970 n/a n/a Did not activate returned for repair
300034013703980 14 Jul 2010 15:40:00 21 Jul 2010 14:50:00 Reset on 21 Jul 2010 to 10 minute pattern
300034013706970 14 Jul 2010 15:40:00 18 Jul 2010 22:00:00 4 day life
300034013700980 14 Jul 2010 15:40:00 23 Jul 2010 16:30:00 9 day life

A summary of observations for the Clearwater buoys is provided in Table 6. These buoys exhibited the following problems:

  • interval errors caused mainly by misreported time in SBD attachment; initial checks confirmed that messages sent at proper interval;
  • problems also occur because of date out of range (from 2007) in SBD attachment; and,
  • (0, 0) coordinates reported.
Table 6: Observations f/Clearwater Buoys - Vessel Deployment #1
IMEI Start Tx (GMT) Last Tx (GMT) Comment
300034012139730 13 Jul 2010 15:20:00 4 Aug 2010
Some gaps in received messages; 22 day life in water, then apparently beached, but kept transmitting until 31 Aug 2010, 16:00:00
300034013012930 13 Jul 2010 15:00:00 28 Aug 2010 13:30:00 Some gaps in received messages; 46 day life
300034013012940 13 Jul 2010 15:00:00 5 Aug 2010 05:00:00 Some gaps in received messages; 22 day life
300034013011950 14 Jul 2010 15:30:00 24 Aug 2010 00:00:00 41 day life
300034013013930 14 Jul 2010 15:30:00 29 Aug 2010 16:00:00 37 day life
300034013016940 14 Jul 2010 15:30:00 15 Jul 2010 02:10:00 32 day life

Vessel Deployment #2 – Placentia Bay, NL

Vessel Deployment #2 Summary

Near Mortier Rock, 47 01.286N 55 00.700W
CCGC W. Jackman
October 13, 2010
Sea State
1-2 m waves
13 knots

This vessel deployment took place on October 13, 2010 and is summarized in Table 7. Video of the entire deployment procedure was recorded for use as a training tool.

Table 7: #2 Summary - Bouys
Buoy Type Quantity
MetOcean (New) 6
Clearwater 2
Total 8

A summary of observations for the new generation MetOcean buoys is provided in Table 8. All of these buoys exhibited the following problems:

  • gaps in unique SBD attachments (interval errors), not in receiving SBD emails; problem much less severe than in Vessel Deployment #1.
Table 8: Observations for MetOcean Buoys - Vessel Deployment#2
IMEI Start Tx (GMT) Last Tx (GMT) Comment
300234010307990 13 Oct 2010 15:50:00 17 Oct 2010
4 day life, buoy retrieved float untangled then redeployed
300234010306990 13 Oct 2010 15:50:00 26 Oct 2010 08:00:00 13 day life
300234010305980 13 Oct 2010 15:50:00 25 Oct 2010 07:30:00 12 day life, buoy retrieved float untangled then redeployed
300234010406000 13 Oct 2010 15:50:00 17 Oct 2010 00:00:00 4 day life, buoy retrieved float untangled then redeployed
300234010405000 13 Oct 2010 15:50:00 21 Oct 2010 04:00:00 8 day life
300234010403000 13 Oct 2010 15:50:00 17 Oct 2010 00:00:00 4 day life

A summary of observations for the new generation Clearwater buoys is provided in Table 9. These buoys exhibited the following problems:

  • the tape on the drogues took longer than 20 minutes to dissolve, so the buoys were retrieved and the tape removed, allowing the drogues to deploy; and,
  • some interval errors (messages).
Table 9: Observations for Clearwater Buoys - Vessel Deployment #2
IMEI Start Tx (GMT) Last Tx (GMT) Comment
300234010301990 13 Oct 2010 16:22:20 24 Oct 2010
11 day life, did not fully deploy from container, retrieved, released from container and redeployed
300234010300990 13 Oct 2010 16:30:00 31 Oct 2010 02:30:13 18 day life

Vessel Deployment #3 – Halifax, NS

South of the Halifax Traffic Zone
CCGC Edward Cornwallis
March 15, 2011
Sea State
1 m waves
Table 10: Vessel Deployment #3 Halifax, NS
Buoy Types Quantity
MetOcean (New) 6
Total 6

A summary of observations for the new generation MetOcean buoys is provided in Table 11. These did not exhibit any tangling of floats as observed in previous vessel deployments.

Table 11: Observations for MetOcean Buoys - Vessel Deployment #3
IMEI Start Tx (GMT) Last Tx (GMT) Comment
300234010113400 15 Mar 2011 14:30:00 30 Mar 2011
15 day life
300234010114390 15 Mar 2011 14:40:00

24 Mar 2011 14:40:00

9 day life. Some missed positions.
300234010117380 15 Mar 2011 14:40:00

28 Mar 2011 05:30:00

13 day life
300234010118380 15 Mar 2011 14:10:00

26 Mar 2011 08:00:00

11 day life
300234010118390 15 Mar 2011 14:30:00

29 Mar 2011 21:00:00

14 day life
300234010119380 15 Mar 2011 14:40:00 22 Mar 2011 23:30:00 7 day life

Vessel Deployment #4 – Grand Banks

On December 16, 2010 DFO Science and the CCG deployed 35 drifter buoys on the Grand Banks. The following tables are a summary of the MetOcean (Table 12) and Clearwater (Table 13) buoys.

Table 12: Observations for MetOcean Buoys - Vessel Deployment #4
IMEI Start Tx (GMT) Last Tx (GMT) Comment
300234010110390 16 Dec 2010 12:10:00 22 Dec 2010 20:00:00 6 day life
300234010110400 15 Dec 2010 13:50:00 26 Dec 2010 06:00:00 10 day life
300234010111390 16 Dec 2010 13:50:00 21 Dec 2010 13:30:00 5 day life
300234010111400 16 Dec 2010 12:00:00 29 Dec 2010 04:00:00 13 day life
300234010111400 16 Dec 2010 13:50:00 21 Dec 2010 18:30:00 5 day life
300234010113390 16 Dec 2010 10:00:00 21 Dec 2010 21:30:00 5 day life
Table 13: Observations for Clearwater Buoys – Vessel Deployment #4
IMEI Start Tx (GMT) Last Tx (GMT) Comment
300034013140130 n/a n/a Did not activate
300034013146130 n/a n/a Did not activate
300034013148130 16 Dec 2010 14:40:00 26 Dec 2010 15:30:00 10 day life
300034013140130 n/a n/a Did not activate
300034013149130 16 Dec 2010 20:30:00 25 Dec 2010 03:00:00 9 day life
300034012139730 16 Dec 2010 12:30:00 25 Dec 2010 20:00:00 9 day life

Derived Benefits:

  • Vessel deployments were critical in identifying design problems that lead to specific manufacturer remedies.
  • A video of the vessel deployment procedure was created for training purposes.

Air Deployment

A total of two air deployment exercises were conducted at CF METR, near Nanoose, BC—the first in November 2010, and the second in March 2011. Each air deployment exercise is treated separately in the following subsections.

Air Deployment #1 – CF METR, November 22-23, 2011

The objective of this Air Deployment was to deploy the SLDMBs, supplied by the two manufacturers, from an aircraft while observing their flight characteristics, the deployment of the drogue and antenna in the water, and to confirm the operation of the Iridium communication and GPS positioning. Testing of the MetOcean units was divided into two phases. In the first phase ballistics units were dropped from the aircraft in order to observe their flight characteristics. In the second phase operational units were deployed. On completion of the MetOcean phases, the testing moved onto phase three. In this phase Clearwater SLDMBs were deployed from the aircraft. Video recordings were made of all SLDMBs from deployment out of the aircraft until splash down into the water.

Prior to testing, the SLDMBs from each manufacturer were brought to the aircraft to test their ability to pass through the SLDMB deployment tube. After observing the operation of the Clearwater buoy through the deployment tube, it was decided that the removal of the two narrow white rings on the buoys’ outer housing would prevent the buoys from getting stuck in the tube. The MetOcean buoy did not require modification.

The weather conditions during testing were sunny, variable wind, and a temperature of -3ºC. The sea temperature was 7º C, and the sea state was zero.

In the first phase, four ballistic units from Metocean were deployed from the aircraft at an altitude of 300 feet and an airspeed of 120 knots. The buoys met the performance criteria outlined in the SLDMB Air Drop Test Plan, specifically:

  • buoys remained intact during deployment;
  • parachute deployed fully; and
  • buoys followed smooth trajectory into the water with no oscillations or tumbling.

In phase two, 16 operational MetOcean SLDMB’s were deployed. Table 14 summarizes the test results. Unless otherwise noted in the table, the buoys were deployed from the aircraft at an altitude of 300 feet and an airspeed of 120 knots. After completion of the MetOcean units, the representative from MetOcean departed from the test range.

In phase three, six operational Clearwater SLDMB’s were deployed. Table 15 summarizes the test results. Unless otherwise noted in the table, the buoys were deployed from the aircraft at an altitude of 300 feet and an airspeed of 120 knots.

All buoys which surfaced from phases two and three were tethered near the CFMETR jetty for a period of five days. It was noted that rougher than normal sea conditions occurred while the buoys were tethered and some of the units did not float upright due to the manner in which the tether was affected by the sea conditions. After five days, the tethered buoys were recovered, washed with fresh water, powered down, and packaged for return shipment to C-CORE.

Table 14 and Table 15 provide a summary of observations from the MetOcean and Clearwater deployments, respectively, including the time of the first and last iridium message. In summary, for the MetOcean SLDMBs: four units (serial numbers 8, 10, 17 and 18) failed to surface; four units (serial numbers 7, 9, 14 and 19) deployed with tangled floats; two units (serial numbers 13 and 15) deployed upside down; one unit (serial number 16) stuck in the aircraft deployment chute, was freed and deployed, but failed to transmit; and five units (serial numbers 5, 6, 11, 12 and 20) deployed and transmitted normally. In summary for the Clearwater units, all SLDMBs deployed and transmitted normally with the exception of one unit (serial number 23) where it was observed that the parachute did not fully deploy.

Table 14: Observations for MetOcean Buoys Air Deployment #1
Serial # IMEI Start Tx (GMT) Last Tx (GMT) Comment
5 300234010113400 23 Nov 2010 19:30:00 30 Nov 2010 16:00:00 Preconditioned to -30 C
6 300234010114390 23 Nov 2010 19:40:00 30 Nov 2010 19:00:00 Preconditioned to -30 C
7 300234010114400 23 Nov 2010 20:10:00 24 Nov 2010 22:30:00 Tangled float
8 300234010115400 n/a n/a Did not surface
9 300234010115400 16 Dec 2010 20:30:00 25 Dec 2010 03:00:00 Tangled float
10 300234010116400 n/a n/a Did not surface
11 300234010117380 23 Nov 2010 20:30:00 30 Nov 2010 19:00:00 No Issue
12 300234010117390 23 Nov 2010 20:30:00 24 Nov 2010 20:30:00 No Issue
13 300234010118380 23 Nov 2010 22:50:00 30 Nov 2010 18:00:00 Deployed upside down
14 300234010118390 23 Nov 2010 21:30:00 30 Nov 2010 22:40:00 Tangled float
15 300234010119380 23 Nov 2010 22:50:00 30 Nov 2010 19:00:00 Dropped from 200 ft, deployed upside down
16 300234010119390 n/a n/a Dropped from 200 ft, stuck in launch tube
17 300234010307890 n/a n/a Dropped from 200 ft, did not surface
18 300234010308930 n/a n/a Dropped from 200 ft, did not surface
19 300234010309890 23 Nov 2010 21:50:00 24 Nov 2010 00:40:00 Tangled float
20 300234010309930 23 Nov 2010 21:50:00 23 Nov 2010 23:50:00 No Issue
Table 15: Observations for Clearwater Buoys - Air Deployment #1
Serial # IMEI Start Tx (GMT) Last Tx (GMT) Comment
21 3000340130111950 23 Nov 2010 23:47:00 29 Nov 2010 15:00:00 No Issue
22 3000340130111380 24 Nov 2010 00:20:00 30 Nov 2010 14:30:10 No Issue
23 3000340130114730 24 Nov 2010 02:50:13 29 Nov 2010 16:30:12 Dropped from 200ft, parachute did not fuly deploy
24 3000340130112000 23 Nov 2010 23:55:24 30 Nov 2010 11:30:15 Dropped from 200ft
25 3000340130111000 23 Nov 2010 23:58:00 30 Nov 2010 11:00:11 Dropped from 200ft
26 3000340130114000 24 Nov 2010 00:10:00 29 Nov 2010 14:00:17 No Issue

Air Deployment #2 – CF METR, March 14, 2011

The objectives of this test were similar to the previous one. Particular attention during this test was given to the following items:

  1. observe the separation of the SLDMBs from the aircraft, parachute deployment and the flight path into the water;
  2. check the water deployment of the antenna, drogue and floatation, paying particular attention to the following previously observed failures:
    • float tangling during deployment;
    • upside down deployment; and
    • failure to surface.
  3. confirm the operation of the Iridium communication and GPS positioning after deployment.

Only one manufacturer, MetOcean was involved in this round of tests. In total, 12 SLDMB units were deployed. Except for serial numbers 1 and 2, which were dropped from the aircraft at 200 feet and an airspeed of 120 knots, all of buoys were deployed from an altitude of 300 feet and an airspeed of 120 knots. Video recordings were made of all SLDMBs from deployment out of the aircraft until splash down into the water. Where possible, underwater video was taken of the SLDMBs in the water. The weather conditions during testing were cloudy with a few showers, and variable wind and a temperature of 7 ºC. The sea temperature was 7 ºC, and the sea state was zero. The results of this test are provided in Table 16

In summary, five units, Serial numbers 5, 7, 8, 11 and 12, did not surface after launch. Serial number 10 sent garbled reports. MetOcean observed that the seawater switch was shorted causing the unit to turn on during shipping, thus discharging the battery. Serial number 4 sent only one position message. The remaining five units appeared to be operating normally. All seven units that surfaced were recovered and returned to MetOcean for post analysis.

Table 16: Observations for MetOcean Buoys – Air Deployment #2
Serial # IMEI Splash (GMT) Start Tx (GMT) Last Tx (GMT) Comment
1 300234010130120 17:25 17:40:00 19:50:00 Approx. 10 min to fully deploy drogue
2 300234010131120 17:33 17:50:00 20:00:00 Approx. 2 min to fully deploy drogue
3 300234010133120 17:39 17:50:00 20:00:00 Approx. 6 min to fully deploy drogue
4 300234010133130 17:46 n/a n/a Only one Iridium message
5 300234010134120 17:53 n/a n/a Did not surface
6 300234010136110 17:59 18:20:00 19:50:00 No comments
7 300234010137110 18:04 n/a n/a Did not surface
8 300234010138110 18:10 n/a n/a Did not surface
9 300234010139110 18:17 18:30:00 20:00:00 Surface immediately
10 300234010134030 18:21 n/a n/a No Iridium messages received, floats tangled
11 300234010136040 18:23 n/a n/a Did not surface
12 300234010137040 18:28 n/a n/a Did not surface

Derived Benefits:

  • The air deployments exposed the buoys to the most rigorous and realistic testing environment;
  • Air deployments were critical in identifying design problems that lead to specific manufacturer remedies.


The Test Plan was developed to evaluate an SLDMB configuration that would meet air drop and vessel deployment requirements. The objective was to have a buoy(s) that passed testing, were in preproduction phase, and were ready for production procurement.

Based on the results of the testing performed, the objective was only partially achieved. This is not unusual considering the complexity of the product development and the timeframes in place to achieve the objectives. However, substantial progress has been made. It is highly likely that a fully compliant configuration will be available by the Fall of 2011. A compliant vessel deployment configuration now exists.

The Test Plan included check-out tests in a wave tank and open water, a suite of environmental testing similar in nature to key sonobuoy environmental tests, extended sea trials, air cannon testing, and air drop tests.

The problems observed during the extensive testing can be categorized as:

  • design related;
  • problems with data; or
  • miscellaneous.

These problems are further expanded upon below:

Design related observations

The design related observations were:

  • a non-compliant mechanical design that would not achieve certification by similarity;
  • buoys not surfacing during air drop testing (“sinkers”);
  • buoys’ floats tangling resulting in lack of proper drogue deployment;
  • variances in operating life; and
  • issues with the vessel deployment procedure.

The non-compliant mechanical design was the most important observation, as it potentially limited one manufacturer from participating further in the program. While this manufacturer had difficulty in meeting all the requirements for an acceptable air drop (either through performance related issues or probable lack of “approval”), they did initially have reasonable success in the vessel deployments. The other manufacturer, who had a compliant mechanical design, had operational issues, both in vessel and air deployments. Consequently, CCG agreed to proceed with two configurations:

  • a vessel-deployable-only configuration; and
  • an air-deployable configuration.

The sinkers were the second most important observation. Due to the difficulty in retrieving the buoys that did not float, failure analysis was limited to un-observed probable causes. The analysis is focused on the bottom ballast and end plate design, and its ability to operate at various angles of water entry. One modification has been implemented and a second air drop test executed, but the modification did not prove to be successful with five more sinkers on the second test. Further analysis and in-house testing at the manufacturer has produced a likely root cause and a modification has been implemented. At the time of this report local testing is being performed to evaluate its impact.

Observations of tangled floats were limited to one manufacturer’s buoy. This symptom resulted in improper drogue deployment and therefore would preclude representation of total water current. The symptom also resulted in an upside down buoy deployment. A fix to the tangled float condition was implemented and appears to have been successful, as evidenced by the sea trials in December, 2010, sea trials in March 2011, and air drop testing of March 2011.

The operational life of the buoys was originally specified as 15 days with a storage requirement of two years. This was subsequently modified to five days operation and three years storage life. The requirement for data during actual SAR operations rarely exceeds three days. The longer operating life supported the collection of data for scientific purposes. This additional data is used to validate or calibrate ocean current models which can make data used for future SAR operations more accurate. Both manufacturers easily meet the current requirement for five days. One manufacturer has a significantly longer operating life that would be better suited for scientific missions. However a range of buoys exist that are better suited for purely science missions.

The vessel deployment procedure proved problematic for operators on the deck of a vessel, even in minimal sea states. This was related solely to configurations designed to meet both air deployment and vessel deployment operations.

One manufacturer used a gas cylinder to eject the buoy from the outer housing. The ejection mechanism was activated by water. Even though the gas cylinder was the same one used for lifejackets, etc., this created a concern for personnel in handing a product with a gas cylinder in dry conditions (e.g., in the aircraft) and reluctance to handle the product in sea spray conditions. It is important to note that the concerns were related to personnel perceptions with the product, not actual safety hazards. In addition, the outer housing was left in the water once the drogue was ejected and this debris was deemed unacceptable.

The other manufacturer’s buoy required an extra process in punching out a bottom plate assembly just prior to vessel deployment. This proved to be more difficult than originally anticipated as the hands-only process would not remove the plate and pry-tools such as screwdrivers were needed to execute the deployment procedure. This procedure was deemed unacceptable.

The solution for vessel deployment operations was to allow a vessel-deployment-only configuration that eliminated the packaging associated with the buoy outer housing. A sealed bag containing the buoy that could be torn open and hand deploying the buoy was successfully tested.

Data Related Observations

Data reliability has been an issue and continues to be an issue in some areas. Data reliability includes lack of GPS fixes, lack of transmissions received, incorrect message formats, and bad data.

The data reliability appears to be improving from both manufacturers. Some of the message formats can be attributed to simple assumptions that were made by all parties that needed to be discussed further while other issues are a result of the protocols implemented.

Incorrect message formats appear to be resolved with the C-CORE development of a SLDMB pre-loader module as a front end to CANSARP that will accommodate Iridium based buoys. The data is now easily ingested into CANSARP and new buoys from other manufacturers can be easily accommodated.

Problems with the data occur when there are missed GPS fixes or buoy transmissions that are not received. Missed GPS fixes were a concern in the early designs as one manufacturer’s buoy had a low profile in the water and was perceived to be susceptible to wave wash-overs resulting in missed GPS fixes. Additional buoyancy was added to increase the antenna height out of the water.

There was some problem in reports from one buoy type, where new, valid GPS fixes were not obtained by the buoy for consecutive reporting intervals. In such cases, the last known fix was embedded in the message and reported to show that the buoy was still operational. However, it was not clear in the report whether the buoy had not obtained a new fix, or simply had not moved. There is a need to make the difference clear so that the web portal can appropriately deal with this report and not send potentially confusing data to CANSARP.

Vessel deployment #4, in Dec 2010, showed one manufacturer with 100% of buoys performing well with data reliability and accuracy, while a second manufacturer providing erroneous readings. This issue has not been resolved at the time of this report.

Miscellaneous Observations

There were a variety of failures that were related to workmanship, poor connection reliability, poor parts reliability, etc. These failures are typical of a program involving prototype development. The failures were documented and resolved to the satisfaction of C-CORE. Such failures included:

  • lack of transmission due to poor antenna connection;
  • lack of transmission due to excess foam covering the water switch;
  • switch failures;
  • lack of drogue deployment due to too much soluble tape being used; and,
  • insufficient flotation.


It is evident that the buoy development program is still a work in progress. The difficulty in meeting the design constraints imposed by the DND air drop certification by similarity is evidenced here. The option of implementing a new air drop certification program for a new non-standard design has significant cost and schedule impacts.

Clearwater achieved higher performance levels in buoy reliability in both air drop and sea trials, but this is based on a simpler design approach that would not meet ‘certification by similarity’. Metocean is still progressing towards acceptable performance levels with a design that is constrained to existing aircraft stores, and therefore should meet certification by similarity.

Because neither manufacturer has achieved a single buoy configuration that meets the needs of both CCG and DND, a vessel-deployment-only is deemed to be the only viable product ready for production at this stage of their developments. As a side benefit, a vessel-deployment-only configuration has a much easier handling and operational procedure for personnel on deck and minimized the debris either on the vessel or in the water. Both manufacturers can produce a more cost effective vessel deployment configuration, but data reliability concerns still exist with Clearwater.

At this time, Metocean is the only viable source for an air deployment configuration that could meet certification by similarity. A recent air drop test (March ‘11) showed that the tangling float failures appear to be resolved but the sinker failure still exists. Metocean is continuing to invest in this product development and in resolving this failure mechanism. A new round of air drop testing is being conducted locally. The results will not be available in time for the submission of this report, however Metocean has indicated that these results will be made available to CCG and DND.

Communications Activities

The communication of this program was focused on partners or collaborators that could support the development of the SLDMB. These included the US Coast Guard (USCG), world renowned scientists, DND, and key players in the oceanographic manufacturing sector.

The USCG is embarking on a similar program for an Iridium based SLDMB with TWC-following drogues and a smaller form factor (‘A’ size or similar) than their current supply.

During the early stages of this Canadian program there was discussion on the requirements of both USA and Canada, and investigation into areas where the specifications could be merged to meet both markets. The objective was to produce an incentive for manufacturers to participate by presenting a larger combined market during production. The discontinued operations of SLDMB production by the existing supplier in Canada (Cobham) raised concerns about similar occurrences in the future.

Communications where held with:

  • USCG R&D Center in New London, CT;
  • USCG HQ, DC; and,
  • USCG Air Station, Elizabeth City, NC.

Although there were some differences in the specification, the end product was similar in many respects such that the same basic design could be used for both markets with reasonable modifications.

Meetings were also held with the oceanographic community, primarily in the USA, to investigate research on the potential drogue designs for following TWC. The organizations included:

  • Scripps Institution of Oceanography (Physical Oceanography Research Division);
  • University of California Santa Barbara Campus (Physical Oceanography: Earth Research Institute); and,
  • the following manufacturers:
    • Clearwater Instruments, MA, USA;
    • Pacific Gyre, CA, USA;
    • Metocean Data Systems, NS, Canada; and,
    • Technocean, FL, USA.

Meetings were held with DND and the Directorate of Aerospace Equipment Program Management – Maritime (DAEPM(M)) to review the specification, test plan, and potential certification process(s). The objective was to ensure the output from this project would meet the needs of both Canadian end users.

Bibliography Reference

Papers/Publication/Reports derived from this project:

“SLDMB Functional Specification.” C-CORE Doc. No. R-09-002-660, vers. 2, January 2011.

“SLDMB Web Application Suite—Software Requirements Specification.” C-CORE Doc. No. R-09-078-660, February 26, 2010.

“Self Locating Datum Marker Buoy (SLDMB) Position Prediction—Analysis of Models.” C-CORE Doc. No. R-11-005-660, May 2011.

“SLDMB Test Plan.” C-CORE Doc. No. R-09-087-660, March 2010.

“Test Report: Qualification Testing of SLDMB Sonobuoy Assemblies (Report 01).” Environmental Simulation Labs Report Number ESL-09-086/Rep.01, April 15, 2010.

“Test Report: Qualification Testing of SLDMB Sonobuoy Assemblies (Report 01).” Environmental Simulation Labs Report Number ESL-09-086/Rep.02, May 31, 2010.

Wells, J. “Results of SLDMB Prototype Field Trials.” Canadian Coast Guard - Maritime Search and Rescue, April 2011.

Papers/Publication/Reports relevant to this project:

Davis, R. “Drifter Observations of Coastal Surface Currents During CODE: The Method and Descriptive View.” Journal of Geophysical Research, Vol. 90, No. C3, pp. 4741-4755, May 20, 1985.

Niiler, P.P., Davis, R.E. and H.J. White. “Water-following characteristics of a mixed-layer drifter.” Deep-Sea Research, Vol. 34, No. 11, pp. 1867-1881, 1987.

Niiler, P.P.,et. al.. “Measurements of the water-following capability of holey-sock and TRISTAR drifters.” Deep-Sea Research, Vol. 42, No. 11/12, pp. 1951-1964, 1995.

Ohlmann, C. and A.L. Sybrandy. “A Catch-and-Release LaGrangian Drifter for Near Shore Ocean Circulation Research.” Proceedings of California and the World Ocean ’02: Revisiting California’s Ocean Agenda, pp. 1262-1265.

Ohlmann, J.C. et. al. “GPS-Cellular Drifter Technology for Coastal Ocean Observing Systems.” American Meteorological Society, Vol. 22, pp. 1381-1388, September 2005.

Suggested Follow-Up/Additional Activities

There are three main areas for future efforts and follow-up, discussed below.

Vessel deployment configuration

The vessel deployment configuration is almost ready for operational use. The following action items are recommended:

  • MetOcean must re-test the current configuration used for the March 2011 sea trials for shock and vibration environmental tests due to changes in mechanical design from that originally tested;
  • Clearwater must investigate data errors from the December 2011 sea trial and test any implemented fixes. Re-test the current configuration for shock and vibration environmental test; and,
  • updated pricing and delivery information should be obtained pending successful implementation of any fixes and environmental testing is complete.

Air drop configuration

The following action items are recommended for MetOcean:

  • monitor results of local air drop testing;
  • make available at no charge to MetOcean the facilities at CF METR for further air drop testing to evaluate fixes for sinker failures;
  • perform shock and vibration testing on final configuration; and,
  • obtain updated pricing and delivery information.

Clearwater Instruments is not a viable option for certification by similarity in its current configuration. C-CORE has been advised that Clearwater is pursuing approaches to repackage their buoy in a configuration that will meet certification by similarity. Follow-up is recommended directly with Clearwater Instruments on the status of their initiative.


The following recommendations are for potential enhancements to the web portal:

  • The position prediction (PP) tool was developed in Matlab™, and thus requires the support and installation of the Matlab™ Compiler Runtime (MCR) library on the SLDMB server. This library needs to be loaded upon every invocation of the PP tool. Through use of the portal it’s become apparent that for large, multiple data sets, the multiple invocation of the MCR library results in appreciable delays. The PP tool could be optionally re-written in Java to avert this problem.
  • The underlying mapping component of the portal was chosen on the basis of programmability and minimal licensing encumbrances. While the mapping ability of the portal was a secondary requirement to its data processing, archiving and uploading features, the detail and usability of the map is inferior to that of mainstream mapping tools such as Google Maps™. However, some of these mainstream tools have licensing regimes, which, at the time of the portal development, were deemed limiting, and especially concerning in the context of data accessibility privileges and security. This could be revisited in the future should a need arise to improve the mapping component of the portal.
  • It has become apparent, as more buoys are deployed and the data archive grows, that there is a need for better management of buoy IDs. It is especially difficult to locate specific buoy IDs in the archive; therefore an integrated search tool may be of use in the future.
  • The adopted SCM tool has demonstrated some sluggishness, and in some cases an inability, to process very large data sets, especially where large numbers of buoys are selected for current-map generation. A number of potential avenues of investigation have been identified, including: a comparison of Linux versus Windows platforms; a comparison of 32-bit versus 64-bit platforms; and data partitioning. Data partitioning will require careful investigation into maintaining the integrity of current-map frames while processing smaller segments of a complete track. An in-depth understanding of the SCM algorithm is a prerequisite to implementing a partitioning methodology.

For More Information Contact

National Search and Rescue Secretariat
275 Slater Street, 4th Floor
Ottawa, ON K1A 0K2

Tel: 613-996-2782
Fax: 613-996-3746

Web Site: National SAR Secretariat website

Sponsor/Project Manager

Fisheries and Oceans Canada, Maritime Search and Rescue
PO Box 5667
St. John’s, NL A1C 5X1
Responsible Officer: Brian Stone, Superintendent
Tel.: (709) 772-2123
Fax.: (709) 772-5369
Email: Brian Stone