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Example 4

1378* ENGLAND - Enst Coast - Tliames Estunry - Barrow Deep - Drying hciglit. Deptlis. Sourcc: Port of London Aulhorily

Chart 1183 (INT 1561) [fuwious updatc 1119/03 ] ILTRS89 DATUM

Insert	drying licight jj, and exlcnd Om contour SSE. lo cnclosc depth 82 and c.\tend lOm contour SSE. lo cnclosc	5I°37'-68N., r !3’*22E. 5T 37'*51N„ r 13'-36E.
Chart 1975 f prcvious updaie U i 9/03 I ETRS89 DATUM
Insert	drying hcighl and c.\tcnd diyiug contour SSE. to cnclosc	(a) 5I°37'-68N., 1° I3'-22E.
	dopili 0$ and c.\lcnd 2m contour SSE. lo cnclosc	51° 37‘'63N.. 1° 13'-38E.
	dcptli 8, andextend 1 Om contour SSE. to cnclosc	51° 37-5 IN.. 1° 13'*36E.
Delete	dcptli 3,, close W. of:	(aj abovc.
	depth Oj . elose NNW. of:	(aj above.

Notes

ln Lhis example some new deptlis havc been inserLed. This has changed the posilion of ihe contours which now nced Lo be extended around Lhe deptlis. Posilion the new depths, cilher by using Ihe tracing (if you have one) or by accuraiely plotting troili lhe nolice to mariners. You may havc lo arrow the deptlis in place. Extend the contour lines around tlio posilion of tlie new depths tlien delete the okl parts of the contour Iiiies in lhe usual way.

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