constant ship and draught survey

offshore Marine Surveyors from constellation Fujairah has a number of experienced surveyors to carry out investigations on behalf of projects agents, shipowners, charterers, P & I clubs. The constant ship is the difference between a ship and its design lightship displacement when i.e
 lightship displacement = lightship weight + constant light boat. The lightweight vessel and includes full equipment, spare parts of the engine room, water in the boiler and the lubricating oil in engines. And these are not included are the staff, goods, fuel, stores and water. Once the manufacturer declares the lightweight - it becomes permanent for the ship. The lightship plays an important role in all stability calculations and survey project.

constant ship and draught survey- Reasons for change

•   Sedimentation in oil tanks or ballast fuel.    
•  Hull fouling.
•  accumulation coating (painting, tank coatings)
•   Garbage collection (particularly in the hold)   
•   Changing the ship spaces.
•   The accumulation of stores (eg in the paint locker, engineering shops, spare parts)
•   Refit, revisions, addition / removal of equipment. 
•  Generally the lightness of a ship will increase over time particularly ships that are subject to corrosion and ships that are not regularly dry-docked. 
• One estimate of the lightship increase rate is 0.5% per year. However vessel of light design is included for all survey project calculations.

Therefore, the constant changes due to the increase in weight of the light ship. A draft survey is a method of determining the weight of the goods by ship displacement calculations, the empty and loaded, taking account of any change in weight bunkers, ballast and consumables on board. 

constant ship and draught survey- important points to remember

An important point to consider is the density of water. If the density of water are not included in the calculations - there will be a shortage of freight which will be reflected in the calculated figures. Due to the water density change can be because water is not sea water, but brackish water. The density of water also depends on the season - summer, winter or the effect of the tide. Density are commonly used to determine the density of water. Two types of hydrometers are used - survey project of hydrometer which is calibrated under vacuum and the load line density meter is calibrated in the air.