Karnaphuli Tidal Draft: Schedule, Gauge and Movement Order

Practical position. Tide prediction is one input only. Match the official CPA schedule, observed gauge and the vessel-specific pilot instruction for the same date and station. A missed tidal window can mean pilot cut and another wait at outer anchorage.

Every agent who has worked Chattogram long enough has had the conversation where an owner asks "why can't we just come in now" and the honest answer is the tide isn't there yet. The Karnaphuli isn't a deep-water port in the way Singapore or Colombo is, it's a tidal river port, and the channel depth a vessel actually gets depends on what the moon is doing that week, not just what's printed on the chart. Queue position, berth prospect, permissible draft (confirm with current CPA/pilot guidance for date and LOA), pilot boarding and cargo-working conditions can change with the latest CPA notice, tide, traffic, equipment, labour and receiver readiness.

What the tide actually does to your draft

The Karnaphuli runs semi-diurnal tides, two highs and two lows a day, with a range that swings between about 2.0 metres on a neap tide and 5.5 metres on a spring tide. That difference is the whole story. A vessel drawing 9 metres might clear the bar comfortably at high water on a spring tide and find itself locked at anchorage with a genuine draft shortage at a neap low. Chittagong Port Agent does not publish or control a fixed draft limit. The Chattogram Port Authority determines the applicable permissible draft and movement conditions from the current tide, hydrographic information, vessel particulars and berth or route.

As a rough planning figure, 9.5 metres is the ceiling most agents quote for daylight transit, dropping half a metre for vessels over 186 metres (confirm against the current Chattogram Port Authority schedule) LOA, and tightening further at night. Night navigation caps out at 175 metres LOA regardless of draft. None of these are numbers you should fix a charter party around without checking the day's actual tidal window first, we've had vessels turned away from a slot they were quoted three weeks earlier because the survey had moved since.

The Kutubdia-to-Alpha run

Inbound vessels don't go straight to the river mouth. The standard approach takes a vessel from Kutubdia to Alpha Anchorage (the outer anchorage) following BA Chart 84, and the advice every pilot gives is to time departure from Kutubdia roughly three hours ahead of high water at Alpha so you arrive on the rising tide rather than fighting it. Get that timing wrong and you're either burning fuel holding position offshore or arriving too late to catch that day's pilotage window.

Pilotage only runs on the tide too

This catches first-time callers out more than anything else: pilotage from anchorage to jetty berthing is only available at high tide during the day. There's no round-the-clock pilot boarding the way there might be at a deep-water port. If a vessel misses the window, it waits for the next one, which, depending on where the tide cycle is, could mean a twelve-hour delay rather than a quick turnaround. Building that into a voyage estimate up front saves a difficult conversation with charterers later.

Monsoon makes it worse, not better

Between June and September the tidal amplitude increases under monsoon influence, which sounds like it should help deeper-draft vessels but in practice adds unpredictability, heavier rain disrupts discharge schedules (jetty cargo work often stops outright during rain), and the same months bring the cyclone risk that can shut anchorage operations entirely with little notice. Vessels planning a Chattogram call across the monsoon window should build in more schedule slack than they would for a December or January arrival.