MSC 70/11/1

4　　　　No South African chart existed covering the Alphard Banks at the time. However, when SA Navy chart SAN 121 was published on 30 May 1980, It also depicted the six mile area, centred on position 35°02'.40 S, 20°51'.80 E, based on the least depth of the Alphard Banks (15.5 m) as determined by a survey of the area carried out in 1956 by the survey vessel SAS Protea.

5　　　　Subsequently, a new chart SAN 57 was used for depicting the two aforementioned separation schemes. However, the six mile radius around the Alphard Banks did not appear on this chart. It is presumed that it was for this reason that the relevant United Kingdom Hydrographic Office information as well as that on SAN chart 121, was not taken into account when the Alphard Banks separation scheme was drafted.

Proposal

6　　　　It is, therefore, requested that the separation scheme at the Alphard Banks as proposed by South Africa and adopted by MSC 69, be considered as replacing the United Kingdom Hydrographic Office's original "Area to be avoided" and that the six mile circle of arc on chart BA 2083 be deleted. The reasons for this are as follows

.1　　　　The original "Area to be avoided" was evidently introduced to warn vessels off the Alphard Banks allowing for a considerable margin of safety due to the Inadequacy of navigation aids and marks in the vicinity of this hazard. The Decca system in existence at the time was probably not considered to offer sufficient navigational accuracy to vessels in the area.

.2　　　　The advent of the GPS/GLONASS position fixing systems presently offer the requisite navigational accuracy for safe navigation in the vicinity of the Alphard Banks.

.3　　　　The proposed separation scheme serves the same purpose as the original "Area to be avoided" and furthermore has the added advantage of routeing vessels Into east and west bound traffic lanes.

.4　　　　The segment of arc that would intrude into the northern traffic lane of the scheme may introduce an element of uncertainty for mariners using the lane.

Action requested of the Committee

7　　　　The Committee is requested to consider the foregoing and take the appropriate action as requested at paragraph 6.

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ANNEX

OFF ALPHARD BANKS

　

I:/MSC/70/11-1.WPD

　

　

　

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