Navigation:  Quick Start Tutorials > Hull Assistants

This tutorial shows you the basics of creating a new hull in Orca3D using the Hull Assistants.

The Hull Assistants are intended to speed the process of creating a 3D surface that you can modify to create your final hull shape. While it's unlikely that they will automatically create your final hull form, they can get you close very quickly. Once the 3D surface is created, you can modify it using the Orca3D control points, watching the sections and hydrostatics updating in real-time as you go.

There are three Hull Assistants:

The Hull Assistants are accessed through the Orca3D Hull Assistant Library:

Clicking on the + sign next to each assistant type will display a list of all of the saved settings for that assistant. For each of the three types, there is a default set of input values. Clicking on the + sign next to a particular assistant in the list (Default or one of your saved assistants) will show the input values for that assistant.

After you have modified any of the default values in the Hull Assistant dialog, you can save the values under a different name, so that you don't have to begin with the default values each time. These assistants are stored on your computer, in the directory C:\Documents and Settings\All Users\Application Data\DRSC3ATC\Orca3D, in a file called Orca3DHullAssistants.xml. If you wish to share a hull assistant with someone else, select the assistant and click on Export Selected. The recipient can then use Import from File... to add the assistant to their library.

To use one of the assistants, follow these steps:

1. Begin by selecting one of the Hull Assistant types from the Hull Assistant Library dialog, and click on Open Assistant (if you click on Create Hull, the hull will be created using the settings in the chosen assistant). The appropriate dialog will be shown:

Note that there may be more than one tab in the dialog

2. If you'd like to preview the hull as you change the parameters, check the Preview Hull box.

3. If you'd like to see Sections on the preview, check the Sections box. 21 evenly spaced stations will be shown.

4. If you'd like to see the Hydrostatics as you preview, check the Preview Hydrostatics box. See Real-Time Hydrostatics for more information.

5. To save the settings as a new Assistant, change the Description field, and then click Save Settings.

5. After all of the parameters are set, click Create Hull.

If you want to edit the hull that was just created, use OrcaPointsOn () to see the surface's control points. These are identical to the standard Rhino control points, except that sections will automatically update when the Orca control points are moved. Also, the hydrostatics can update in real-time as you move Orca control points, if you have selected the Real-Time Hydrostatics option in the dialog that defines the Design Hydrostatics condition.

 

Definition of Input Values for the Planing Hull Assistant

The Sheer Ht. Position is a fraction of the Length on Deck, and the Sheer Height is a fraction of the Deck Ht. @ Bow. Bottom Rocker, Bow Rake Angle, and Transom Rake Angle are in degrees.

The Beam on Deck is in current length units. The Deck Beam @ Transom and Chine Beam @ Transom are fractions of the Beam on Deck, and the Max Beam Position is a fraction of the Length on Deck.

Bow Fullness and Bow Rounding control the deck shape near the bow. As Bow Fullness is increased, the maximum deck beam is carried further forward. As the Bow Rounding is increased, the deck edge becomes more perpendicular to centerplane.

 

 

Definition of Input Values for the Sailboat Assistant

 

The Sheer Height Position and Canoe Body Draft Position are both a fraction of the Length on Deck. The Sheer Height is a fraction of the Deck Height at Bow. Transom Rake and Bow Rake Angle are in degrees, and the other values are in the current length units.

The profile of the sheerline is constructed as an arc. The three points that define the arc are the stem, the transom corner, and the Sheer Height/Position. Similarly, the bottom profile is an arc, defined by the transom height, the forefoot (whose "tightness" is controlled by the Forefoot Shape), and the Canoe Body Draft/Position.

The Beam on Deck is entered as the total beam. The Beam @ Transom is defined as a fraction of the Beam on Deck (i.e. a Beam @ Transom of 1.0 would imply no longitudinal taper).

A forefoot shape of 0.0 yields a sharp corner (discontinuity), and a value of 1.0 yields a very "soft" forefoot.

The Deadrise value controls the slope of the surface as it runs from the bilge toward the centerline, and the Flare value controls the shape as it moves up from the bilge towards the sheer. A Deadrise value of 0.0 means that the surface will approach the centerline horizontally, and a Flare value of 0.0 means that the surface will approach the sheer vertically.

The shape of the hull is also controlled by the Bilge Tightness. A value of 0.0 yields a very tight corner. The higher the value, the more slack the bilge will be. Bilge Tightness and Deadrise/Flare are interrelated, so some experimentation with these values (with Preview) turned on may be required to attain the desired shape.

 

Definition of Input Values for the Ship Hull Assistant

The Ship Hull Assistant has three tabs; Dimensions, Hull Form, and Bow/Transom controls. The various input parameters are described below, but the best way to learn about the controls is to experiment with them. By checking either Preview Hull (which shows the edge curves and isoparms) or Preview Sections (which displays 21 evenly space stations and the edges), you can see the hull change in real time as you adjust the various parameter. By checking Preview Hydrostatics, you can see various hydrostatics parameters update as you modify the controls (note that on the Real-Time Hydrostatics display, you can select which hydrostatic parameters to view).

When you are happy with the shape of the hull, simply click on Create Hull. The Ship Hull Assistant will close, and the hull is created, together with matching flat deck and transom surfaces. If you'd like to save the settings to use as a starting point for your next design, enter a Description at the top of the dialog, and click on Save Settings. If you already have saved the settings with the same Description, you will be asked if you want to overwrite them.

 

Dimensional values are displayed in the following figure. Note that some of the values are actual dimensional values (in length units or degrees), and some are expressed as ratios. For example, the sheer is defined by three points; the tip of the stem, the transom/deck intersection, and a third Sheer Height point. This point is defined by the Sheer Height (a fraction of the Depth at Bow), and the Sheer Height Position, a fraction of the Length on Deck (which defines the longitudinal location of the Sheer Height point).

 

The Longitudinal Prismatic Control shifts volume to the ends of the hull (higher value), or away from the ends (lower value). Volume is shifted to the ends by making progressively more columns in the control net the same shape as the column in the Max Area location.

The Stem Curvature controls the shape of the stem in profile. A value of 0 yields a straight stem; positive values result in a clipper bow.

The Max Area Location shifts the longitudinal location of the column in the control net that has the maximum area. Note that this will not correspond exactly to the location of the station of maximum area at a particular draft.

The Beam On Deck is a dimensional value (meters, feet, etc.). The Transom Deck Width is expressed as a fraction of the Beam on Deck.

 

There are three Section Tightness controls; Forward, Mid, and Aft. As the Tightness value is lowered, the rows in the control net are brought closer to the bilge corner.

 

In addition to Section Tightness, there are three other controls on section shape; Deadrise, Side Slope, and Flare, each of which are specified at Forward, Mid, and Aft locations. Deadrise controls the angle of the section as it moves outward from the centerline. Side Slope controls the angle of the sections as they move down from the sheerline. Flare introduces curvature into the sections in the topsides.

 

The Forefoot Shape control allows for a very "tight" or "loose" corner between the centerline profile curve and the stem curve. Curvature continuity is guaranteed, unless a value of 0.0 is entered (sharp corner).

 

Fullness, which has controls for both fore and aft, gradually scales the control columns in or out.

 

The Ship Hull Assistant is constructed with a tangency control column just aft of the stem, which always ensures that the waterlines will end perpendicular to the centerplane. The Bow Rounding control determines how far out this perpendicularity extends, by moving the tangency control column inboard and outboard. Note that other controls, such as the Deck Taper, use this column in the control net to determine the location of other columns, so the influence of adjusting the Bow Rounding will be faired into the rest of the hull.

 

That shape of the centerline in the aft portion of the hull is controlled by three parameters:

 

See also:

Hull Design