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Hull and Outfitting

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Powering Data Dialog - Loading Tab

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  • Last UpdatedDec 18, 2025
  • 4 minute read

Powering Data Dialog - Loading Tab

All of the loading conditions required for the powering calculations should be set up using this tab sheet. You may Add and Delete conditions as required. Conditions may be deleted by highlighting one or a number of columns. The Delete button will then be activated so that you can delete the conditions.

Note:
That the design condition cannot be deleted.

Note:
Once a condition has been added or deleted, the undo/redo facility is re-initialized, so you will not be able to undo grid operations. Any subsequent operations can be undone/redone in the usual way, until the next Add or Delete.

Loading conditions previously defined within Hydrostatics may be selected, and these use the hydrostatic properties of the vessel, as calculated by Hydrostatics as input. Different loading conditions may be entered and these allow you to enter any draught, and indeed any hydrostatic properties. However, the facility to automatically calculate the hydrostatics from the vessel has been implemented.

The grid control has been designed so that information can be copied and pasted between loading conditions, or indeed between applications!

The following is a brief description of each item in the grid control:

Condition

By default, a User Defined condition is created, that is, it is independent of the Loading Conditions previously set up in Hydrostatics. However, each loading condition is included in the drop-down list, allowing you to easily perform powering calculations on defined loading conditions. Note that if a defined loading condition is selected, then you may not change the Name, Draughts or fields calculated automatically.

Automatic Update

Checking this button will automatically update certain fields by calculating the properties. The following values are calculated:

  • CB

  • LCB from midships

  • CM

  • Wetted Surface Area

  • CWP

  • ½ entrance angle.

This item is only available for a User Defined condition, and if it is checked, and you changes either the Draft Aft of Draft Fwd, then values are again automatically updated on the fly.

Note:
That you may not alter the above six values when this box is checked. you may however, check the box to obtain calculated values, then uncheck the box to alter any/all of the calculated values.

Name

Condition Name

Draft Aft

The draught at the aft perpendicular.

Note:
This value is only editable for a User Defined loading condition.

Draft Fwd

The draught at the forward perpendicular.

Note:
Again, that this value is only editable for a User Defined loading condition.

Mean Draft

The draught at midships. Not editable.

Trim

Trim by the bow (Tf-Ta). Not editable.

Transom Area

Transom area.

Length WL aft A.P.

Length of the waterline aft of the AP. Used to calculated the length on the waterline.

Bulb length fwd F.P.

Length of the bulb forward of the FP. Used to calculate the overall length of the vessel for the Guldhammer & Takashiro methods.

Bulb section area

Cross-sectional area of the bulb (forward of the FP).

Bulb centroid height

Vertical center of area of the bulb.

CB

Block coefficient =.

LCB from midships

Longitudinal Center of buoyancy.

CM

Midship area coefficient.

Chine Length (Lp)

Length of chine (high speed, planning craft only).

Mean Beam over Chines

The average beam over the length of the chine.

Deadrise angle at 50% Lp

Deadrise angle at the center of the chine.

Calculate Wetted Surface

This is NOT to be mistaken for the "Automatic Update" cell described above. You can choose either:

  • User Input to enter a value directly

  • Regression to calculate a value from regression formula (dependent on the resistance method chosen)

Wetted Surface Area

You may only enter data in this field if the field above is set to "User Input" and the "Automatic Update" box is unchecked.

Calculate CWP

You may select either

  • User Input to enter a value directly

  • Regression to calculate a value from regression formula (dependent on the resistance method chosen)

CWP

Waterplane area coefficient. you may only enter data in this field if the field above is set to "User Input" and the "Automatic Update" box is unchecked.

Calculate 1/2 Entrance Angle

You may select either

  • User Input to enter a value directly

  • Regression to calculate a value from regression formula (dependent on the resistance method chosen)

1/2 entrance angle

½ Entrance Angle. you may only enter data in this field if the field above is set to "User Input" and the "Automatic Update" box is unchecked.

Demi-hull breadth

breadth of a single demi-hull (catamaran methods only).

Angle of Transom Wedge

Angle of transom wedge (ZIPS method only).

Viscous Resistance Form Factor

Viscous resistance form factor (Pham method only).

Deadrise Angle

Angle of deadrise.

The following table describes which hull form parameters are required by each of the resistance methods. Those values that are NOT required are disabled within the grid control)

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