Trim Optimization model is composed of a software bundle. The computer programs are totally in-house programs written in either Visual Basic or Fortran Programming Languages. The final on-board software is Microsoft Excel Based where visual basic macro run background.

Resistance analysis is based on the model of The Methods of Holtrop and Mennen. But it is should be arranged the wave-resistance and the roughness allowance formulations in the model to satisfy the real tested values in the towing tank test report. Therefore a powerful prediction has been made for the trim lines except that the trim lines for the towing tank tests  have neen carried on.

The same procedure has been applied for quasi-propulsive coefficients. The Holtrop and Mennen Model offers a powerful prediction of such coefficients. A group of scale ratios have been created through known tank test reports and these ratios have been interpolated for other trim lines which do not exist in the towing tank report.

The software used in this phase is a Fortran based which is no visual output. The output of this phase will be the data of the next.

The evaluation of propeller hydrodynamics or, in other words, propeller open water data is indispensible part of this software bundle. The propulsion analyses yielding to the prediction of machinery power can not be performed without propeller open water performance data.

Propeller open water characteristics can be computed via well-established, in-house software's. The software's in that area are three main types. Lifting-line analysis, lifting surface analysis and panel methods. Beside of these commercial CFD software's exist. All methods used in that area needs the use of some special factors. To be a propeller designer or analyst or a knowledge of a commercial software which are popular nowadays are definitely not adequate. It needs fully understanding of nature of propeller and wake flows. This is only done by working in cavitation tunnel or a towing tank or a propeller company. Otherwise the predictions may be wrong !!!

The 3D representation of the propeller whose diameter is 6.3 meters working in 90K DWT BC.

The panel method representation of the same propeller given above.

The Kt-Thrust  coefficient of the same propeller. As it was seen in the picture different algorithms give different results. Choosing the correct value is an expertise type of job. In that example the output from the lifting surface algorithm (Curve Kt-LSM) has been preferred.

All software's used in this phase are Fortran programming language based. The output file of this part will be that data of the next.

Together with the Resistance and propeller hydrodynamic data (open water values), propulsion analysis can be performed to find correct engine power and propeller revolution.

The software used in this phase is a Fortran based which is no visual output. The output of this phase will be the data of the next.

The reporting software is an Microsoft Excel (2013 Version) file working with Visual Basic Macro background. This file groups and creates everything. Produces tables, contour plots etc. It also plays the role of an on-board software obtaining best trim condition for existing load case.

The figure shows one of the outputs of this software. Contour plots can tell important knowledge with a simple plots that can be interpreted via numerous numbers of tables etc.. The plot shown above was created 14 knots of service speed. Iso curves are the main engine loads computed from the previous phase. Therefore the crew can find optimum loading line by inspecting the plot. 

 Another important feature of this software lays on its on-board characteristics. The figure shown below is the main page of the program.

The crew only enters speed, aft and fore drafts initially. The speed is written in B9 cell, aft and fore drafts are written in C9 and D9 cells, power of shaft generator is written in F9 cell; current, wind effects are written in H9 and J9 respectively with their conditions (0=negative, 1=positive, 2=neutral for H10 and J10), power of main propulsion unit is written in cell N9 and and let the program run by clicking "Run Macro" button. The Trim-Engine power curve is generated. Then, by inspecting the nature of plot, the crew should make a decision about the optimum trim. The optimum trim values shown in the graphs may not be applicable practically. But, say, 1 meter trim to bow is written in E9 cell and let the program run for 1 meter trim to bow condition the outputs appear in F14 and F18 cells. F14 cell tells original trim (in this example zero trim) case. F18 cell tells the current 1 meter trim to bow case. The differences are also shown in cells B21 and B22 and their loads are appeared in cells N9 and N10.

As an example of a real case 13.74/12.74 meters of aft and fore drafts, the required engine power is about 7340 kWs. If the captain prefers bow trim condition (12.74,13.74 m aft and fore drafts),  the engine power would have been 6998 kWs, therefore 4.7% power gain could be obtained. The software can produce this plots for different ships' speeds.

Excel Version of the Program

In addition to excel version of the program, a new version developed under Visual Basic 2010 is introduced.

Standalone file version of the program