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Author Topic:   Vessel Traffic Control Radio
jimh posted 04-10-2013 04:17 PM ET (US)   Profile for jimh   Send Email to jimh  
Commercial vessel traffic transiting the Detroit River and Lake Saint Clair between Lake Huron and Lake Erie is subject to coordination by vessel traffic control. A Canadian Vessel Traffic Station in Sarnia operates on VHF Channel 12 for the segment of the passage from Lake St. Clair down bound to the Detroit River Light in Lake Erie.

Commercial vessels are required to call in at certain points along the way. The mandatory call-in points are:

--the Detroit River Light, at the lower end of the river in Lake Erie

--Grassy Island, a demarcation point where the river broadens to a wide and deep channel

--Belle Isle, near the upper end of the Detroit River, where it flows into Lake St. Clair, and

--St. Clair Light (known as the Crib Light), about mid-way across the lake.

Upstream of the St. Clair Light the traffic coordination channel changes to VHF Channel 11, and continues to Port Huron and Sarnia.

Here is a recording of a typical radio exchange. An up-bound vessel, the JAMES R. BARKER, calls in to report their arrival at Grassy Island, and gives their estimated time to reach the St. Clair light.

Sarnia Traffic radio acknowledges their call-in, and then gives the vessel a list of segments in the river where docked vessels have requested that passing traffic slow down or "check down". The segments are identified by the names of the firms that run the docks. Sarnia Traffic also gives the up-bound vessel a list of down-bound vessels it may encounter.

Here is a recording of the radio traffic:

jimh posted 04-10-2013 04:23 PM ET (US)     Profile for jimh  Send Email to jimh     
The "crib light" is called that because it was originally built up from the lake bottom on a large crib made from timbers and filled with large stones. It is now a modern light with a cement-filled caisson-type base, but all the lake captains still call it "the crib light."

I think the phrase "check down" comes from the old days of steam, when a steam engine pressure was limited by a check valve or something like that. To run under check was to reduce steam pressure or slow down. Captains still ask other captains to "check down" when passing if they want them to slow down and reduce the wake being created.

jimh posted 04-10-2013 09:03 PM ET (US)     Profile for jimh  Send Email to jimh     
In the U.S. Costal Pilot No. 6 CPB6_E43_C07_20130406_1206_WEB.pdf

there is a notation on the section for the Detroit River under the heading Navigation Regulations that directs mariners to 33 CFR 162.130 for information on traffic regulations. It is there that the frequency scheme is set out, along with the reporting points, See

jimh posted 04-10-2013 09:59 PM ET (US)     Profile for jimh  Send Email to jimh     
As a sidebar, it seems that requests from moored ships that passing ships "check down" have become very common now, and it may be in part due to the tragic events of the BUFFALO passing the JUPITER in the Saginaw River in 1990. For some interesting reading see

jimh posted 04-11-2013 09:26 AM ET (US)     Profile for jimh  Send Email to jimh     
Vessels transiting between Lake Huron and Lake Erie often ask Sarnia Traffic for information on the water level in the lower Detroit River, particularly the water level at the gauge in Gibraltar. NOAA has a water level gauge there. I don't know how Sarnia Traffic gets the data. Here is the NOAA website with the water level gauge data:

Although the water level on the above page is tracked in meters, the information Sarnia Traffic gives out is always in units of inches above low-water datum. Perhaps they take the data from this source: shtml?station_info=9044020+Gibraltar,+MI&glin=1

In the table (linked above) the water level in decimal inches above LWD is given every six minutes. The latest data is at the bottom of the table. As I am writing this, the water level is

04/11/2013 09:12:00 EDT -99.99 26.81

That is 26.81 inches above low-water datum. Many of these loaded ships are sailing close to the bottom and the real-time water level is of interest to them. I have observed some down-bound ships go to anchor before transiting the Lower Detroit River if the water level reading at Gibraltar is too low for their master's liking.

For more water gauge stations, see

dfmcintyre posted 04-11-2013 01:12 PM ET (US)     Profile for dfmcintyre  Send Email to dfmcintyre     
I use this site:

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