Automatic Identification System
Vessels equipped with AIS can achieve collision avoiding, information exchange, vessel positioning, distance alarm, etc. It makes up ARPA collision avoiding radar's disadvantage in monitoring objects in heavy rain, and solves difficulties in location accuracy, identification of vessel type. It also helps a lot in harbor management.

Advantages:
Safe
Actively sending vessel's dynamic information lets around vessels equipped with AIS know its existence and direction in order to avoid collision accidents.

SOS message can be sent though pressing emergency call button when accidental situation occurs.

Real time
Real-time sending vessel's information at defined time. Sending frequency varies from status.

AIS Class-B Speed Report:
Different type of information has different time interval, which requires different update speed.

Static information: Update once every 6 minutes or when data is revised.

Dynamic information: It depends on changing situation of sailing speed and sailing direction. Detailed data refers to following table.

Sailing Status
Update frequency

Sailing speed < 2 kt
3minutes/time

Sailing speed >2 kt
30seconds/time

AIS base station
10seconds
AIS Class-B Successful Case

1. BACKGROUND
China Zhoushan fishery belongs to North Pacific fishery, which is one of the world's four major fisheries. It is same famous as Hokkaido fishery, Newfoundland fishery and Peru fishery. Zhoushan fishery is the biggest in-shore fisheries in China. There are 10, 000 fishing boats and more than 150, 000 fishers during flood peak.

During fishing process collision accidents between fishing boats and merchant ships are very easy to occur because of worse environment and lack of collision avoiding equipments on fishing boats. This kind of accident takes 98% of all fishing accidents. Statistics shows that from 2002 to 2007 there were 115 collision accidents happening between Zhoushan fishing boat and merchant ship, which caused wreck of 42 fishing boats, death of 148 fisher and a direct economic loss of more than RMB20, 000, 000.

2. SUCCESSFUL CASE
During January to October, 2008, more than 5000 sets AIS products made by Tianjin 712 Communication & Broadcasting Co. Ltd. Have installed on fishing boats in Zhoushan, which has successfully prevented occurrence of collision accidents.

Case1
At 9: 50 p. M. On April 5th, 2008, a foggy day, when Zhejiang fishing boat 42115 anchoring at 122 degrees 36 minutes east longitude, 29 degrees 38 minutes north latitude, terminal in AIS Class-B marine automatic identification system used on fishing boat sent out distance alarm as a merchant ship was coming close. The alarm informed the ship crew, most of whom were having rest, to evacuate in time. All 12 crew members were saved by nearby fishing boats. Above fact shows that application of this system can effectively prevent occurrence of major accidents.

Case 2
At 11: 40 p. M. On February 27, 2008, Zhejiang fishing boat 42265 was wrecked by an unknown merchant ship at 122 degrees 52 minutes east longitude, 28 degrees 09 minutes north latitude and 9 crew members on board were all missing. Wrecker ship escaped. Then through AIS Class-B terminal SOS message with accurate accident location was sent out to nearby boats. After receiving report of the accident, Ocean and Fishery Bureau in Zhoushan immediately take rescue actions and tracked suspicious ships according to vessel's trace in system's platform. The wrecker merchant was caught due to AIS Class-B terminal's cooperation with Ocean and Fishery Bureau's in-time dispatching of fishing boats, coordination of the maritime police boats and sea plane's monitoring.