ECCC's 3-meter discus buoy

NDBC's station pages name 22 of Bluegraph's stations as 3-meter discus buoys owned and maintained by ECCC: 13 off British Columbia (46131, 46132, 46146, 46147, 46181, 46185, 46204, 46205, 46206, 46207, 46208, 46303 and 46304), six in the Great Lakes (45132 and 45142 in Lake Erie, 45135, 45139 and 45159 in Lake Ontario, 45143 in Georgian Bay) and three off Nova Scotia (44258 Halifax Harbour, 44488 East of Chedabucto Bay and 44489 West Chedabucto Bay). Bluegraph counted them from those pages in October 2026.

The count may be low. Six more stations are listed as ECCC's 6-meter NOMAD buoys, though a 2021 paper says ECCC replaced its last NOMAD with a 3-meter discus in 2019. Eight more ECCC buoys in the Great Lakes have pages that name no hull. Two of them, 45147 and 45149, give a 5 m anemometer height, ECCC's nominal height for this hull, but they aren't counted here.

The hull was designed at the Woods Hole Oceanographic Institution and modified by NDBC and Environment Canada. Canada moored its first one in May 1986 in Douglas Channel, south of Prince Rupert. It is welded aluminum, 3 m across, with six watertight buoyancy compartments around a watertight central compartment for the electronics, batteries and sensors. An aluminum superstructure and a steel substructure are bolted on. The builder gives a weight of 1,500 kg and a height of 3.4 m, which its photograph shows to run from the keel to the top of the tower; ECCC gives 1,540 kg deployed.

Its ballast is chain, attached to the mooring yoke and the mooring, not weight inside the hull. ECCC moors it in coastal waters up to 60 nautical miles offshore and on the Great Lakes, in 14 to 2,950 m of water: all chain in water up to 70 m deep, and an inverse-catenary mooring in deeper water. Bluegraph's 22 are in water from 22 m deep (45132, in Lake Erie) to 2,950 m (46208, off Haida Gwaii).

The two agencies' buoys use the same disk but work differently. NDBC's current payload sits above the deck in sealed tubes on a low frame, with ballast in the hull; ECCC's sits inside the hull, in the central compartment, and its ballast hangs below on chain. NDBC's buoy carries one propeller-vane anemometer 3.8 m up and a sonic sensor beside it; ECCC's carries two propeller-vane anemometers on masts above a tall tripod tower, the upper one 5 m up.

NDBC's motion sensor measures the hull's tilt and heading as well as its heave, which gives the direction the waves come from. ECCC's Watchman records heave only, so its buoys report how high the waves are and their period, but not where they come from. NDBC's buoys send the weather every 10 minutes; ECCC's report once an hour. The fender is black rubber on NDBC's buoys and a red bumper on ECCC's.

ECCC's buoys carry AXYS Technologies' Watchman, which samples the sensors, calculates the readings and sends them to shore: the Watchman 100 by GOES satellite and, since 2021, the Watchman 500 by Iridium. It is powered by primary batteries and by batteries charged by solar panels.

In the builder's photograph, a tripod tower rises from the edge of the deck, with two tiers of solar panels around it and the navigation light inside. Two masts on top each carry a propeller-vane anemometer, and a satellite antenna stands beside them. The same photograph shows ECCC's Halibut Bank buoy (46146) behind it, with a taller frame and its panels arranged differently, so the figure shows one arrangement, not every buoy's. The air and sea temperature sensors and the barometer are not shown, and their heights are not published, so the figure doesn't draw them.

The Watchman measures waves with an accelerometer strapped down in the hull. Each hour, it records the hull's vertical acceleration once a second for 2,048 s, about 34 minutes. From that record, the payload calculates a spectrum in 41 frequency bands, from 0.0039 to 0.4812 Hz, and from the spectrum the significant wave height, the highest wave and the peak period. ECCC describes the wave height and period as averaged over 30 to 35 minutes each hour.

Bluegraph shows the wave height and dominant period that NDBC relays from these buoys. They report no wave direction or average period, and NDBC publishes no spectra for them, so Wave Intelligence doesn't cover them.

ECCC gives the wind speed as a 2-minute mean before the hour, and the gust as the highest in the 10 minutes before the hour. The anemometers are about 5 m above the water, higher than the 3.8 m on NDBC's discus buoys, which matters when comparing the two. As NDBC relays them (October 2026), the speeds are in whole meters per second and the directions in tens of degrees.

Pressure, air temperature and sea temperature are the latest values on the hour. Bluegraph shows them as NDBC relays them, with the 3-hour change in pressure; these buoys report no dew point.

Each buoy reports once an hour, by GOES or Iridium satellite. Fisheries and Oceans Canada's Marine Environmental Data Section archives the reports, and NDBC relays them; Bluegraph collects them from NDBC.