A multi-chine hull may consist of for example topsides, spray rail and a bottom panel. The properties of these panels can be very different. For example: where the spray rail can be a linear panel (zero curvature transversely), the topsides and bottom may have some curvature. Especially when the design is built out of aluminium or steel and all panels will have to be expanded into flat plate stock for cut production geometry, it is therefore often a good idea to use separate surfaces for each panel. Bonding is used to weld or glue the panel (read: surface) edges together.

 Watch a video shows the procedure of bonding two surface edges and shows what happens when you try to bond two edges without matching stiffness. This video also shows how to use the Duplicate Surfaces command to ensure that both surface edges share the same properties. [Web | Disk]

Start

In this section we will again start a design from scratch. If you have an existing design open, you will have to close it first.

Ø  Select File | New Design.

We will start by inserting a flat, longitudinal plane which will become the Topsides surface:

Ø  Surfaces | Add Surface | Buttock plane

Ø  Resize the surface to have a length of 40 m and a depth of 3 m.

Ø  Save the design as Bonding_Start.msd.

The surface should look like this in the perspective window:

Ø  In the Profile window add 3 control point columns. Try to distribute the columns as in the image below:

Control point distribution with increasing density towards the right
(which will become the bow).

Ø  In the Surface Properties dialog, name the surface “Topsides” and set the longitudinal flexibility to 4.

Remember that there are several ways to get to the Surface Properties:

§   Surfaces | Surface Properties …

§   Double click on the surface in the Assembly Pane

§   Using the right click menu from the Assembly Pane

§   The Properties Pane

Ø  Save your design

Ø  Move the surface 5m to starboard and 5 m up.

You can do this for example by using the Surfaces | Move Surfaces | Numerical menu option, or setting all control points on the surface offset position to 5 m.

Moving the selected surface 5 m transversely to starboard and 5 m up.

Ø  Close the bow by moving the fwd-most column of control points transversely to the centreline. Do not change their longitudinal position.

One way of doing this is by selecting both control points in the fwd-most column and then setting the Controls | Control Properties to 0 m offset. Another way would be to use a selection box in Plan view to select both control points on the fwd-most column and then drag them to the centreline while holding the shift key down. Tip: when a surface is symmetrical, you can drag control points past the centreline (to the portside of the centreline) to snap them to the centreline.

You should now see something like this in Plan view:

Ø  We do not need to see the Grid, so Display | Hide Grid

Ø  Save your design.

Let’s leave the Topsides surface for what it is now and move on to inserting a chine surface.

Inserting the Chine

Ø  Lock the Topsides surface

Repeating almost all of the steps above:

Ø  Insert another Buttock plane, resize it to 40 m length by 3 m depth, insert 3 columns of control points in roughly the same longitudinal positions, change the colour and rename this surface to Chine.

Ø  Unlock the Topsides and save your design as Bonding_Chine.msd

You are now ready to bond to bond the lower edge of the Topsides with the upper edge of the Chine.

Ø  Switch to Perspective window

Ø  Make sure you have Display | Contours | Bonded edges switched on

Ø  Read the section on Bonding Surfaces in the Maxsurf manual up to the “Bonding with Tangent Continuity” section.

In this tutorial we will use the edge selection method to bond the edges. We could have chosen to use the edge control points with exactly the same outcome.

Ø  Select the Lower Topsides edge (1)

Ø  Holding the shift key down, select the Upper Chine edge (2)

Ø  Now select Controls | Bonding | Non-Tangency (3)

You will see the following error message:

This is because we have “forgotten” to set the Chine’s longitudinal stiffness to 4 (the same as the Topsides).

Ø  Set the longitudinal stiffness of the Chine to 4 and repeat the 3 bonding steps above.

You should now see something like this:

Notice how the Chine Top edge was moved towards the Topsides Bottom edge. This is because we selected the Topsides  Lower edge first. Also notice how the names of the two bonded edges are displayed in the lower left hand corner of the Maxsurf application window. This means that Topsides Bottom and Chine Top edges have been bonded with a non-tangent (C0) transition.

Ø  Switch to Plan view

Ø  Select the aft 4 control points on the centreline row of the Chine surface with a selection box. 

Ø  Holding the shift key down, drag the selected control points outwards until the roughly the required chine shape is obtained (something similar to that shown below).

Plan view

Ø  Switch to Profile view

Ø  Set the Height in Control Properties of the lower edge of the Chine to 3.5 m and Move the Fwd Top corner control point of the Topsides surface to shape the bow:

You should now see something like this in rendered Perspective view with Display | Half off.

Ø  Save the design

You are now ready to insert the bottom surface.

Inserting the Bottom

The final surface we want to create is the Bottom surface. Instead of creating this surface from scratch and set it up so that its edges match that of the Chine and the Topsides, it is much faster to duplicate for example the Chine surface or the Topsides surface and use that. This then automatically gives us a surface edge with identical stiffness and number of control points.

Ø  Surfaces | Duplicate

Ø  Try to select just the Topsides surface. Notice how the Chine is also selected. This is because they are bonded.

Ø  Untick the Respect Bonding and deselect the Chine

Ø  Space the duplicate surface 5 m below the Topsides:

Ø  Rename the duplicate surface Hull Bottom.  In the perspective view you should end up with something similar to the following:

Ø  Rename the Copy of Topsides surface to “Bottom”

Ø  Save the design as Bonding_Bottom.msd

Ø  Switch rendering off and Display | Half

Ø  Select the Bottom edge of the Chine (1)

Ø  Select the Top edge of the Bottom (2)

Ø  Bond the two together using non tangent transition (3)

Make sure you don’t accidentally select any of the Topsides edges. You can do that by hiding the Topsides surface or switching bonded edges off temporarily.

Ø  Switch to Profile view

Ø  Set all the Bottom surface’s Bottom edge control points’ offsets to 0.

Ø  Model the Bottom surface’s Bottom edge so that it looks like this:

In rendered Perspective view with Half display off you should see something like this:

Ø  Save your design as Bonding_Bottom.msd

Done! This is basically a very simple starting point for any hullform with a spray rail or chine. Continue with the next section where you will be making Refinements to the Multi-Chine Hull Model. This revisits a lot of steps from the tutorial where you modelled your first design as well as fairing tips.