A lesson in AIS

June 4, 2009

PRIDE is sailing!!! We have no engine noises! Most all of the sail is set.

0900 hours
Position: 31D 11/6 North X 72D 20.3 West
Course and Speed: 100 Magnetic and 7.6 to 8 knots
Wind:  15 knots SSW
Barometer: 1018.0 rising from 1017.0 at 0400 EDT
Sky: a few scattered cumulus clouds
Sea: 3-4 ft swell
Air Temp: 79 F

Yesterday there was a lot of rain cloud scattered about…not as much this morning and nearly none since midnight. We have had 6 ships pass by since midday yesterday. We have only actually seen two of them. We know that the other four were in our area of the ocean due to the Automatic Identification System (AIS) that is mandatory on all commercial vessels, including PRIDE. Each vessel transmits via VHF Marine Radio Frequencies their position, course & speed. That information is crunched by the calculators in the AIS machine to provide bearings between the ships receiving the AIS signals as well as distances. Aboard PRIDE we have the AIS information sent to the electronic charts on the main computer and we can see an icon of a ship based on their AIS information. Quite often we can “see” ships in our area as far out as 25 miles…sometimes more…but we cannot actually see them as they are “hull down” over the horizon after about 10 miles. This morning we actually saw the BRITISH MERCHANT pass astern of PRIDE at a distance of 3 nautical miles. According to her AIS information regarding ship particulars she is headed to Cove Point. I do not know any Cove Point but the one near the Potuxant River in Maryland. I guess she is bringing cooking gas to the United States and will unload her cargo at the gas piers at Cove Point, Maryland.

Our distance from Bermuda is 385 nautical miles and our distance to get into harbor is 417 nautical miles. At the speed we are sailing now we will be ahead of schedule. Maybe we will go past Bermuda a little and see if we can find some of the European Sail Training vessels racing in a regatta to Bermuda from the Canary Islands.

~Captain Miles


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