- Student involvement
- Redundant development
- Oceanographic standards/configurations
- Contributions to IOOS with common data delivery and archive
History of our drifter production
In 2004, we were funded by NOAA's Northeast Consortium to develop student-built, satellite-tracked, lobstermen-deployed drifters. This was the fourth phase of the Environmental Monitors on Lobster Traps project (see Manning and Pelletier, 2009 and emolt.org). Funded parties including the Gulf of Maine Lobster Foundation, the Southern Maine Community College (SMCC), and NOAA's Northeast Fisheries Science Center were interested in tracking the potential transport of early-staged larvae along the coast of Maine. In subsequent years, we were primarily funded by McGillicuddy et al in another NOAA funded project (GOMTOX) to track the advection of HABs (Manning et al, 2009). Another big boost to the project occurred in the summer of August 2009 when we hosted a NSF-funded workshop to teach a few dozen educators from around the country (from the Marine Advanced Technology Education (MATE) consortium). Applications funded to date include:
- Lobster larvae advection
- Harmful Algal Bloom advection
- Zooplankton (whale food) advection
- Educational demonstrations
- Invasive crab dispersal
- Transient eddy formations
- Fish larvae (salmon,cod) advection
- Power plant effluent dispersal
- Clam acidification
One of the primary motivations for drifter deployments is to help validate the many numerical circulation models as well as the growing network of CODAR systems.
Given multiple years with multiple fundings, the dataset to conduct such statistics is rapidly growing.
eMOLT Drifters vs Davis "CODE" Drifter
Most surface drifters in use today are the "Davis CODE" design first described decades ago by Davis (1985) for the Coastal Ocean Dynamics Experiment. There are specifications and pictures of this type of drifter in each of the manufacturer's web sites below (Table 1). However, since they are often fitted with costly (~$2K) GPS electronics, we found, in our case of very limited budget, it was unwise to use them along the coast of New England due to the high risk of running aground and being picked up by curious lobstermen and pleasure boaters.
Table 1. Some existing surface drifters that have performed
well over the last decade or two
Having eliminated the costly electronics within the housing unit, we simply mount a relatively inexpensive GPS transmitter (similar to those used by the trucking industry on the highway) on
a simple wooden 2" by 4" (ballasted appropriately). While in the past we used a 2" diameter foam-filled PVC pipe and vinyl sails, in 2012 we switched to more
environmentally-friendly wood or bamboo mast and cloth sails. Since most were built by students at the Southern Maine Community College and originally funded by the Environmental Monitors on Lobster Trap project,
these drifters have been called by various names such as the "SMCC/eMOLT" drifters. The various models are named after the students who spent the most time on design and construction.
Our latest models, for example, are called the "Dan Drifter" which used an upside-down ski pole with its tipped sawed off for its transmitter mount and mast extension
and now the "Irina Drifter" which uses an all-aluminum frame. From our experience in using hundreds of these drifters since 2004, we can reduce the cost GPS drifters 3 times. While these homemade rigs typically survive several months, they do not survive nearly as long as the commercial products noted above. Nevertheless, they have so far logged hundreds of thousands of kilometers of ocean. While they are designed to be expendable for the most part, with some effort and ship time, of course, they are reusable. Batteries are good for several months with near-hourly samples. See more on "survival statistics" below.
How the system works and who is involved
There are six institutions/companies currently involved:
- "Gulf of Maine Lobster Foundation" (GoMLF) non-profit processes orders
- "AXXON" manufacturers the GPS transmitters
- "Southern Maine Community College Marince Science Department" often build some the units
- "CommTech Mobile DataCom", now owned by "ORBCOMM", is the satellite service provider (like ARGOS)
- "Globalstar", the folks that float the low-orbitting satellite
- "NOAA" promotes the use of these drifters and processes the data
Interested scientist and educators communicate with:
- Erin at GoMLF (207-985-8088, firstname.lastname@example.org) to process orders
- Jim at NOAA (508-495-2211, email@example.com) to discuss hardware/software issues
It is best to copy all parties in your email communications. The
complete process is documented here
See the latest construction manual here.
GPS Transmitter Setup
- Programming units on a PC
- download the latest software version 2.7.003 (if not already)
- Install USB driver (if not already)
- Install tracker software (if not already installed)
- Connect wireless dongle to USB port
- Click on tracker software (software steps depends on tracker model)
- TrackPacks (>=2009), for example, use "TrackPack Configurator" java as follows:
- Enter passkey
- Click on "Search for units"
- highlight unit of interest
- select configuration/sample rate desired (typically 24/day samples)
- Click on "configure" on the bottom right panel
- wait a few minutes
- make sure you get a check mark next to id number or try again
- place the transmitter right-side-up in a sky-view position
- Trouble shooting the TrackPack Configurator Driver Installation
- Windows 7 often needs special driver different from the one that comes in the zip file so you need to take the following steps:
1) insert your dongle
2) look in your laptop'c control panel under "devices" and get the name of the device listed, in my case, as "unspecified: Silicon Labs CP210x"
3) search the web for that type of device's driver
4) I found mine here
- Trouble shooting the TrackPack Configurator Program
- try right clicking the Desktop icon for "TrackPackConfigurator" (if you have one), selecting "properties", and changing the "target" location for javaw.exe to some other location where you find it such as "C:/windows/sysWOW64" or "c:/windows/system32"
- try downloading a newer version of Java
- make sure your "TpGui2.jar" file is located where the shortcut icon "start in" field specifies
- try right clicking "TpGui2.jar" and "open with" JAVA
- NOTE: Comtech developers are working on new versions for Win8, Android, Linux, etc
Putting units to sleep
- connect to particular unit as in steps above
- click on "inventory"
- click on "configure"
- make sure you see a "1 successful" notice in the lower tleft
- make sure you get a green check mark next to the ESN number at top of the screen
- put the unit in sky view for awhile to double check the fact that it is really asleep (ie in "inventory" mode)
Documenting deployments and recoveries
In an attempt to automate the operation, users are asked to enter their deployment
information on a web based forms.
While the complete system is not operational at the time of this writing (Sep 2009), the plan is to serve data and googlemap plots without further human intervention.
Tracking Units on the Web
- Option #1: best for getting details of most recent fixes
- log on to https://assetview.tms-orbcomm.com/portal/index.php
- username: <call Jim Manning 508-566-4080>
- password: <call Jim Manning 508-566-4080>
- select unit IDs of interest (pe 0-18766)
- select "messages" to see mapquest-like map of positions
- zoom in and out, click other views, etc.
- Option #2: for summary of all drifter projects this past year
- Drifter Updates site for summary of this years data
- includes links to animations, googlemaps, and actual data
- Option #3: to view and download archived data
Evolution of Drifter Configurations
"Kara" drifter w/drogue
These units, prototyped during the winter of 2004 and 2005, are designed to track a subsurface layer. There are three
components to the unit:
- The drogue is constructed stiff fiberglass hoop rings that supports sheets of heavy-duty vinyl cloth material. The length of the drogue will be adjustable to 1.5 meter lengths. The cloth is glued securely to hoops w/additional strips of cloth in a manner such that the stress is tangential (not normal) to the seam. The bottom-most hoop is weighted slightly and additional buyancy is added to the upper-most hoop to provide a more vertical profile in the water. The cloth has two 30cm-diameter holes cut out in each 1.5m section placed 180 degrees.
- The tether is typically a narrow (1/8t") statinless wire connected to a 3-point bridle on the topmost hoop with a stainless ring (either circular or pear shaped) and a swivelling shackle (1/2" of more). Heavy duty stainless wire used for the bridle will be well protected from chaffing particularly at the ring connection. The upper end of the tether is connected to the underside of the surface configuration. Tether lengths will be adjustable depending on the project and
terminated with thimbles and sleeves.
- The surface configuration of these units has been either:
- 2-3'-length of 4" PVC pipe that simply acts as a platform for the satellite transmitter riding above a 2-3'
length of 2" PVC pipe OR
- a Norwegian float that absorbs the drogue pull with a separate unit tether behind that houses the transmitter. It is usually configured similar to the "rachel" design described above (without the sails). The length of this surface
tether is adjustable.
The design follows the specifications of the World Ocean Circulation Experiment to insure that the units have acceptable drag ratios of more than 40:1 and that slippage is minimized. These units were tested in the spring of 2005. A set of them were deployed in the Bay of Fundy in May 2005 and June 2006 and mid-coast Maine in July 2005 (Aretxabaleta et al, 2009).
"Rebecca" drifter w/telemetered temperature sensors
We have added additional features to the basic design.
- A temperature sensor similar to those used by refrigerator trucks on the highway have been be incorporated by interfacing it with the AXTracker. We tested this feature with at least one unit in April 2005.
- Tension sensors are often included on drogued drifters to indicate the presence or absence of the drogue. Alternatively, we may consider including a temperature sensors immediately above and below the water line such that, given the drogue tension loss, should record detectable variations in air temperature.
- Internally recording temperature probes can be easily installed at multiple depths to monitor the thermal stratification.
- To aid in visibility, orange surface flotation can be easily tethered to the surface configuration and strobe lights can be secure to the PVC housing.
"Paul" drifter w/reinforced construction for inshore work
SMCC student, Paul Hodder designed this more-rugged design for inshore/estaurine work during the 2005-2006 school year. Dozens of deployments have been made since.
"Kathleen" bucket drifter for very-near surface work
This model was originally designed for UMASS's Dan McDonald to look at the top 30cm of the Merrimack River Plume in the Fall of 2009.It is simply an inverted plastic bucket that is properly ballast to float just below the surface. The transmitter is mounted a few inches above the seasurface.
"Super buckets" were also deployed with strobe lights (>4 mile visibility) and internally recording:
- temperature (multiple depths)
- salinity (StarOddi DST-CT)
- more frequent positions (Garmin units)
This drifter was designed to eliminate flotation at the ends of the
sail spars. It uses instead the natural buoyancy of a pressure-treated 4 by
4 fence post. After initial failure in June 2010, we added a few toggle floats and deployed 4 in the Gulf of Mexico successfully.
This drifter was designed to provide an easy-to-ship unit all
contained within a Vinyl 4 by 4 fence post (as sold at Home Depot). After initial
failure in June 2010, we adjusted the flotation to successfully deploy 4 in
the Gulf of Mexico.
This especially low cost drifter was designed
by Vitalii Sheremet to deploy inside harbors or estuaries. They were
successfully deployed by students in kayaks with Cohasset Harbor,
Massachusetts in July 2010.
This drifter, first deployed in mid-June 2010, replaced the "rachel" as the standard model
for a few years. Some of these survive more than 10 months at sea.
It was the least expensive, easiest to make, and most environmentally
friendly of the Davis-style surface drifters until it was replaced by the
"Dan Drifter" in the fall of 2012.
This drifter, first deployed in the summer of 2012, replaced the
Eddie as the standard model. The 2by4 mast was originally extended by lashing a broom
handle with a screwed-on scrub brush acting as the transmitter mount but
those proved to be weak. So, in the fall of 2012, we are planning on an
upside-down ski pole with its tip sawed off as our new transmitter mount.
Most have used wooden dowels for spars but we are not sure how long they
will hold up compared to the fiberglass spars. While we are not sure how long they survive
yet, it is the least expensive, easiest to make, and most environmentally
friendly of the Davis-style surface drifters. Aside from the transmitter and
perhaps the net-buoy flotation, all other parts can be found at most
There are three components to satellite fees (not including the transmitter itself) that the service provider charges:
- one time $30 "provisioning" for each transmitter
- 15 cents per fix
- $2.45/mth "maintenance fee" whether the unit is being used or not
So, if you have a transmitter on your office and you do not expect to use it from more than a year, it is a good idea to "decommission" the unit so the satllite company can't charge the $2.45/mth fee. If sometime in the future you want to use the unit, you can "reprovision" it for $30.
Note that if you set the transmitter to report every hour, your cost will be about $100/mth or (0.15*24*30). If you set it at every 6 hours, your cost will be about $20/mth.
When asked what rate you should set your transmitter, we usually recommend hourly or at least bi-hourly so the tidal oscillations are depicted but, if you are more interested in tracking the unit for several months, you can choose to report less frequently. One set for every hour should last about 3 months and that is often less than the residence time of drifters on the continental shelf.
Id you want your data to be useful to numerical modelers, hourly transmissions are best. We try to keep track of your satellite usage. On a near monthly basis, we update the website
There are two numbers associated with a deployment. The first is the "electronic serial number" of the transmitter (typically 6 digits) that is assigned by the manufacturer. The second is a distinct deployment "ID". This ID is the key field in the database. While it was originally a 5-digit number, in the fall of 2009 it was modified to be a 9-digit number in order to accommodate nation-wide deployments. This ID is automatically generated based on user's entries in the web-served deployment documentation. In other words, users will see what the unique deployment number is after they have entered the deployment information. It is defined as follows:
- 1st-2nd digits = year ("10" for 2010)
- 3rd digit = month (where all drifters dropped Oct-Dec have a month code of "0")
- 4th-5th digit = latitude (integer degree)
- 6th-8th digit = longitude (integer degree)
- remaining digits = consecutive deployment number associated with this geographic and temporal block
EXAMPLE: 098430702 is the 2nd drifter dropped in August 2009 at approximately 43N and 070W
Aretxabaleta, A. L., D. J. McGillicuddy, Jr., K. W. Smith, J. P.Manning, and D. R. Lynch (2009), Model simulations of the Bay of Fundy Gyre: 2. Hindcasts for 2005–2007 reveal interannual variability in retentiveness, J. Geophys. Res., 114, C09005, doi:10.1029/2008JC004948.
Davis, R. 1985. Drifter Observations of Coastal Surface Currents During CODE: The Method and Descriptive View. J.Geophys.Res.,90,4756-72.
Lynch, D.R., D. Mcgillicuddy, J.P. Manning, D. Greenberg, A. Bigili, A. Aretxabelata, 2014. Particles in the Coastal Ocean: Theory and Applications. Cambridge University Press. (In press).
Manning, J.P, 2012. Student-built, fishermen-deployed, satellite-tracked drifters. IOOS summit white paper
Manning, J.P. and E. Pelletier, 2009. Environmental Monitors on Lobster Traps (eMOLT): long-term observations of New Englands's bottom-water temperatures, Journal of Operational Oceanography. Vol 2-1, p.25-33.
Manning, J.P. and J.H. Churchill, 2006, Estimates of dispersion from clustered-drifter deployments on the southern flank of Georges Bank. DeepSea Res. II. doi:10.1016/j.dsr2.2006.08.004
Manning, J.P., D. McGillicuddy, N. Pettigrew, J. Churchill, L. Incze, 2009, Drifter Observations of Gulf of Maine Coastal Current, Continental Shelf