"DraftMaster" is designed on the basis of ECE/ENERGY/19 "Draft Survey Code" recommendations and successfully applied on "river-sea" ships which, owing to the construction features, are classified as "not meet requirements".
Now we operate vessels of the following types: "Volzhskiy", "Volga", "Volgo-Don", "Nevskiy", "Okskiy", "Amur". Vessels of types "Volgo-Balt", "Sormovskiy", "Omskiy" are in a stage of development. The error of calculation of quantity of a cargo on such vessels by any other means can exceed 15 % for the following reasons:
- presence of significant hogging (sagging) and twistings of the hull
- absence of the ship documentation
- unauthenticity of the ship documentation
- presence on a ship of several variants of the documentation
- presence of additional draft marks
- absence of measuring devices in tanks
Presence of such high error is also caused by the subjective factors. While defining the quantity of a cargo the shipmaster or independent surveyor depending on personal experience decide the following:
- method of calculation (ECE/ENERGY/19, " Rules of transportation of cargoes ", etc.)
- which variant of the ship documentation to use at calculation
- what drafts to use at calculation: from extremities or from a cylindrical part of the vessel
- how to calculate draft values on perpendiculars
- what formula to apply to calculation of mean draft ("sea", "river", etc.)
- whether it is necessary to apply any additional corrections to heel, trim, hull deformation
- how to define quantity of an available ballast at absence on a vessel of ballast tables
Thus, the quantity of a cargo is defined on the basis not only of measurings and calculations, but also personal opinion of the expert.
The program "DraftMaster" excludes the influence of the subjective factors on calculation and allows to define quantity of a cargo with the greatest possible accuracy. There is no necessity to drain or overflow ballast tanks. The ship documentation at calculation is not used.
"DraftMaster" is especially effective in cases when the quantity of a cargo while loading is calculated by drafts and while unloading by weighing a cargo on weights.
"DraftMaster" principle of operation
The program is based on a three-dimensional modelling of vessel hull and tanks, according to preliminary made hull measurements and tank calibration.
Calculation of displacement of a vessel is made on the basis of the geometrical description of hull sections for any variants of vessel heel and trim and presence of any hull bending and twisting. On the basis of drafts on marks the drafts for each frame are calculated and then displacement calculated on the basis of submerged areas of the frames.
Calculation of volumes in ship tanks is made on the basis of geometrical characteristics of tanks and their measuring devices considering the angles of local heel and trim in area of each tank.
Accuracy of calculation of weight of a cargo is reached due to the following:
Displacement calculation is based on all nine available draft marks. When the ordinary method of calculation on such vessels is used - a duality always exists, depending on which drafts were used - from hull ends or from parallel middle body. (Note: ECE/ENERGY/19 and normatives of Ministry of Transport of the Russian Federation forbid calculations based on drafts from vessel parallel middle body).
Instead of calculation of mean draft "DraftMaster" makes modelling an actual waterline of a vessel.
There is no necessity to apply the "first" and "second" trim corrections.
While calculating the quantity of a ballast the heel and a trim are considered for each tank separately.
Initial data necessary for calculation are brought in the main working window of the program:
Calculation of a current waterline and calculation of volumes in tanks is made
At zero gaugings in tanks "DraftMaster" calculates the possible volume which is out of reach of the measuring device
The Weight Certificate is printed when necessary. The form and contents can be changed according to the requirements of the customer.