Could you advise about the location of the ballast overboard valve? Observed various different designs depending on the shipyard and the type of the ship (i.e. VLCC and LNG-c). Is the location related to regulation or just a matter of practical consideration?
I also had similar question.
Could observe that ballast pump overboard discharge connection on tankers are designed above deepest ballast water line while same on other type of ships like LNGC, LPGC, RO-RO, Container ship and Bulk carriers are terminating below water line.
Will appreciate if some body explain the reason why tankers have different design.
Can tankers also discharge to below water line?
A reason could be that it the ballast overboard in tankers is designed above the waterline so that the operator/crew can observe the contamination of ballast water from oil, in case of a leakage between cargo and ballast tanks?
George check Marpol Annex I, Chapter 4, Reg 30 “Pumping, piping and discharge arrangement”.
Having in mind also that a cargo tank may carry ballast in rare occasions.
Usually you are putting the overboard near the ballast pumps. No point in spending extra energy by putting the overboard far away from the pump. In bulk carriers the pumps is located in the er so there is located the overboard. In tankers if the ballast pumps are located in the pump room the overboard will be located in the pump room. If the tanker has submerged ballast pumps then the overboard is located near them usually midship. Regarding the location below waterline or not I believe it has to do with the possibility of water ingression in the vessel. In the spaces that are dangerous areas like the ballast tanks in a tanker or the pump room that are not normally manned the overboard should be located above waterline to minimise the risk of unnoticed water ingression.