One Fathom Bank
Permatang Sedepa, the mobile sandbank off the Klang delta, its lighthouse, its traffic separation scheme and the tidal window it imposes on deep-draught transits.
One Fathom Bank, known as Permatang Sedepa, is the shoal off the Klang delta that gives its name to the northernmost traffic separation scheme in the Straits of Malacca and Singapore routeing system. It is the northern limit of the IMO-adopted routeing measures, which run about 250 nautical miles from here to the entrance to the South China Sea near Horsburgh Lighthouse.
The bank is a mobile sandbank lying between features known as North Sands and South Sands, and its charted depths change between hydrographic surveys. That mobility is one reason no littoral state publishes a fixed controlling depth for the Strait of Malacca , and why the operative constraint is the 3.5 m under-keel clearance rule read against the current chart rather than a headline figure.
Rule 7 of the Rules for Vessels Navigating Through the Straits of Malacca and Singapore caps VLCCs and deep draught vessels at 12 knots over the ground at the One Fathom Bank scheme, and the associated precautionary area is named Off Port Klang. The full article will cover the bank’s geology and survey history, the lighthouse, the scheme geometry, and the tidal window a deep-draught ship works to when passing it.