Once a vessel has grounded there are a number of considerations that need to be addressed:
- Has the hull of the vessel been broached during grounding. Sounding all the various tanks that are situated behind the outer hull can check this. If the hull has been broached, then the vessel should not be refloated unless it is determined that sufficient buoyancy and stability remains once the vessel is floating freely.
- Has the hull of the vessel been deformed in any way. This could lead to increased bearing loads on the main engine and/or main transmission shafting
- Has the propeller or rudder become fouled or damaged. Ensuring both units are free to rotate without any excess loads could check this.
- Is the vessel discharging any oil. A check on the tank levels may assist in locating possible damage, but any external pollution should be controlled as soon as practical.
- Are the sea suction intakes blocked/covered by the seabed. Any reduction in the seawater pressure could require that the sea suctions be changed over.
Soundings around the vessel should take place to determine where the vessel has grounded, and the type of seabed on which the vessel is laid.
Once the vessel has been grounded there should be an estimate of when the vessel may be re-floated. This could depend on the local tides, vessel loading condition, and vessel ballast condition. If the vessel were fully loaded, then discharge of the cargo may take a number of days, then it may be prudent to reduce the services supplied by the engine room. This will reduce the fuel consumption whilst aground. The limit of services may be dictated by any possible damage to the vessel’s hull.
One area of concern may be that the if the engine were normally operating on residual fuel, then to keep the fuel injection system warm this has to be circulated at all times. Should a fuel injector be leaking, then this could cause a build-up of fuel on top of the piston, which will cause excessive pressure rises when the engine has started. Thus the main engine should be changed over to diesel oil. This change over must avoid high rates of temperature changes, and once fully flushed the fuel oil system can be shutdown until the main engine is required again.
Once the vessel has been re-floated, then the following inspections should take place:
- An in-water survey should be carried out with the agreement of the Classification Society. This will require that the vessel be in clear water, so that divers can examine the underwater portion of the hull. They will examine all hull plating, looking for dents, holes, etc.
- A function test of the rudder and transmission shafting
- A full set of crankshaft deflections should be taken. The readings obtained should be compared with previous readings, and also be within the engine manufacturer’s recommendations for that engine. Whilst measuring the deflections, bridge gauge readings may also be taken to ensure that the crankshaft is sitting firmly on the lower bearing half.
- Even though the divers are examining the external hull shell plate, it may also be prudent to examine the cofferdam in way of the main engine seating, to ensure that the full strength of this important seating area is intact before engine power is resumed.