Time to Sink

The Time to Sink calculator estimates the time it takes for the inflow of seawater to surpass the vessel's displacement based on the vessel's displacement and the flow rate of sea water entering the hull and the bilge pump rate out.

INSTRUCTIONS:  Choose units and enter the following:

• (VDW) Vessel Displacement Weight
• (BFR) Breach Flow Rate (rate that seawater is entering the hull)
• (PR) Bilge Pump Rate (ejection pump rate of water leaving hull)

Max Time to Sink (MT): The calculator returns the time in hours and minutes.  However, this can be automatically converted to compatible units via the pull-down menu.

The Math / Science

On the outside, best case scenario, a boat will sink when the weight of water coming in through a breach exceeds the displacement weight of the vessel.  Conditions can make the demise (sinking) occur earlier, but the time to take on more water than the boat effectively displaces is the outer limit.  The rate of taking on water is mitigated by the rate of a bilge pump.  If the bilge pump ejects water faster than the boat is taking it on, the boat can float indefinitely.  

Knowing how much time one has can be the difference between life and death in some circumstances.  So please consider that this estimate MAY BE EXCESSIVELY OPTIMISTIC.

The formula used for the Time to Sink is:

t = (VDW/MDSW) / (BFR-PR)

where:

• t = time to sink
• BFR = Breach Flow Rate (water in)
• PR = Pump Rate (bilge pump rate out)
• VDW = Vessel Displacement Weight
• MDSW = Mean Density of Sea Water

Historical Note

The RMS Titanic took on water at an estimated rate of 7 tons (approximately 1,540 gallons or 7,000 liters) per second after hitting the iceberg. This translates to about 420 tons per minute or 252,000 gallons (approximately 1.14 million liters) per minute.  This overwhelming rate of water ingress quickly exceeded the capacity of the ship's pumps, leading to its eventual sinking.

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