Taking on Water - The Causes
There are many reasons for flooding of a ship through taking on water. This is most dangerous when water is taken on into locations that are designated dry areas such as the engine room and cargo spaces.
The most common causes for flooding are noted below;
This can occur at sea or in harbor approaches, usually involving two ships and can cause a lot of damage as shown below from Wikimedia;
This can result in both ships taking on water into the cargo/engine room areas; however the watertight bulkheads that nowadays should extend right up to the main deck level should give protection against overflowing between sections.
The hulls of modern oil tankers are of the double skinned design to prevent pollution following a collision or grounding, but this can also prevent ingress of large quantities of seawater into the crude oil tanks.
We all know of the iceberg that sank the RMS Titanic, almost 100 years ago in 1912. Water spilling from one section into another one could have been prevented if, the watertight bulkheads had extended right up to the main deck level.
Many years ago I was sailing as Fourth Engineer on the MV Fair Head; a cargo ship trading between the UK and Finland. We had rounded the Pentland Firth and a few days later ran into ice packs then sheets of ice. Fortunately, a Russian Ice-Breaker had opened a channel through the thickest ice and we followed this. We picked up the pilot who literally walked out to us, and headed into Kotka to load paper for Liverpool.
As 4th Engineer one of my duties was looking after the fuel oil system that on this ship was marine diesel oil (MDO). I had been taught to check the bunker tanks for water accumulation by operating a ‘foot valve’ on the bottom of the tank. This was located in the engine room and operated by pushing the valve handle with the sole of ones shoe, the resultant outflow spilling into the bilges.
On the voyage home we again encountered ice, and I had noticed a lot of water in the oil when checking the starboard bunker; letting it flow for quite a while until pure diesel was discharged out of the foot valve.
I thought nothing of this (lack of experience) putting it down to condensation due to the ice. However, I did inform the Chief of an anomaly when taking the noon bunker ullages; we were gaining rather than loosing oil in the starboard diesel oil bunker!
We went back down to the engine room and checked the foot valve discharge. This discharged clear water for over 20 minutes; and tasting this he it identifying it as being seawater! We were taking in water to the starboard bunker; and his suspicion that a rivet was leaking proved right after a hull inspection in a Liverpool dry dock; the ice had sheered the head of a rivet.
Now, we do not use rivets any longer for attaching steel plates, but the hull steel plates can spring, affecting their welding. There is a lesson to be learned here for all our young Junior Engineers; sound your tanks regularly and, don’t depend on gauges alone!
- Overwhelmed by Typhoons/Hurricanes
Not a lot we can do about becoming flooded due to a typhoon, other than battening down the hatches, changing course to avoid it and, putting the ships head into the storm and reducing engine speed can lessen the chances of flooding or indeed sinking. This is what is believed to have happened to the MV Derbyshire, an OBO carrier that disappeared with all hands in the China Seas during Typhoon Orchid in 1980.