Ship Data - General

This dialog allows you to setup & define several general options for the project, as described below

Balancing Tolerances

Calc takes the geometric model and balances this for weight and buoyancy to obtain the equilibrium waterline. This is an iterative process and the 'Balancing Tolerances' are used to control the convergence and search length for the final balanced waterline. 'Draft' and 'Trim' (units: meters or feet) control the solution convergence, stopping the search when the changes between subsequent iterations is less than the entered values. 'Max Iterations' stops the calculations at the entered value preventing the program from continuing indefinitely searching for a solution. If the maximum number of iterations is reached, it means that a balanced waterline (that means, a solution) has not been reached. This will be indicated in the analysis window displayed while calculations are being performed.

Water Density

This is entered in tonnes/cubic meter or tons/cubic feet. This is the only place where the density of the surrounding fluid is entered.

Plate Thicknesses

Keel and shell thicknesses are entered in millimeters or inches. Currently, entering a value of shell thickness only affects Hydrostatics, Curves, Deadweight Scale, Launching, Loading Conditions, Deterministic and Freeboard. In these analyzes, a value of shell thickness produces an extreme value of displacement and other associated values.

Propeller

you can enter values for Aft from AP, Diameter, and Shaft Height above baseline (units: meters or feet) which define the location of the propeller, as well as the Required % Immersion (value between 0 - 100). The immersion is taken as the distance the propeller tip is below the waterline and the % Immersion is this value expressed as a proportion of the draft. If values are entered in this dialog, then the system will check for each loading calculation that the required propeller immersion has been achieved and this will be reflected in the output.

Note:
This value is not used in the hydrodynamic modules (powering, manoeuvering and seakeeping).

Empirical Wetted Surface Area

If the Empirical WSA check box has been selected/activated then the system will calculate the wetted surface area of the vessel using the Denny-Mumford formula, rather than use the value determined from the geometry model.

you can also enter a multiplication factor (to make an allowance for appendages, for instance), which is used to adjust the WSA value obtained directly from the formula.

Overhangs

The Stern overhang is the distance to the aft end of the ship from the AP. Similarly the Bow overhang is the distance from the FP to the ship's forward extremity. At the moment these values are only used to limit the frame table, but this might be used for other calculations in the future.