Boat design with free software - Part 2 - Delftship

Part 2: Finalising the hull design in the free version of Delftship
(Part 1 is here)

Delftship is a professional boat design package that offers a powerful free version for the amateur.  There are no time limits but a few features are locked in the free version.  The usability is excellent and even fun, so you might find yourself playing with hypothetical designs just because you can.

Getting Started:
Download and install the free version from here:
http://www.delftship.net/
The help document is long but worth working through.  Don't skip it.
You'll need to understand the basic modelling functions as well as layers, curves, hydrostatics and plate development.

Importing a Carlson Hulls design
If you used Carlson Hulls to to your initial design as described in Part 1, you can import it into Delftship easily.  On the File menu there is an explicit option for importing from a Carlson .hul file and it works.  This gives a nice model with each strake put in a separate layer and curves added to each chine.

Fairing the lines
First hide the control net and show the control curves.
Now when you select a curve you get a great view of the rate of change of curvature.  Smoothing this graph results in a really fair curve.  The full version can do this automatically but doing it manually in the free version is satisfying.

See what happens when a point is moved 3/8" up and across.  Still looks reasonably fair to the eye but this view shows where it isn't perfect.

Plate developments
At one click you can view the plate developments ready to build:

Printing or exporting the developments is one of the features disabled in the free version.  But nothing stopping you marking the offsets directly on to ply from the screen:

Thats the workaround for getting the developments of the hull panels.  But it doesn't get you the dimensions for the sections.  We'll look at that in Part 3.

Exporting to CAD
Delftship supports exporting to dxf file for use in various CAD programs.  On the export menu you can export the 3D mesh or polylines as dxf.  To get the sections you can also view the linesplan and then it gives the option export the lines plan as 2D dxf.

Limitations
The free version doesn't support pitch and heel analysis.  The full version gives pitch hydrostatics.  But to do inclined hydrostatics there's and extra module to pay for.  You did do all the pitch and heel analysis in Hulls as per Part 1 didn't you?  As a workaround for pitch analysis you can use the modify menu to rotate the entire design and then adjust the waterline.   Bit fiddly though.

On to Part 3.

Boat design with free software - Part 1 - Carlson Hulls

Ever the cheapskate I've been working on the Dinghy 1.0 design using free software.  This series of posts will discuss the features of the various free applications I've discovered in my narrow experience and from a first timer's point of view.

Part 1: Roughing out the design using Carlson's classic Hulls software.

After all the software I've played with I think this is the fastest way to get a design started.  And as we'll see in Part 2 it has been so popular that subsequently converting to other file formats is not as hard as you might think.

Getting started:
The Hulls software is available here: http://carlsondesign.com/software/add-ons/shareware/hull-designer
The necessary tutorial to get you started is included in the zip as a pdf.
An alternative tutorial by Gavin Atkin is here: http://home.clara.net/gmatkin/hullstut.htm
Note that Hulls won't run on 64 bit Windows 7.  If like me you are running 64 bit you'll need to install 'XP Mode' from Microsoft first: http://www.microsoft.com/windows/virtual-pc/download.aspx

Capabilities:
Besides the obvious ability to enter your offsets directly and quickly and get a quick 3D view, Hulls gives some basic hydrostatics as well.  Importantly you can also do pitch and heel analysis to see the changes to waterline shape as well as movement of the centre of buoyancy and centre of lateral resistance.  You can also produce development patterns for a sanity check and estimate of the material required.

Limitiations:
For a start its for hard chine boats only.  This of course can include wooden boats with any number of strakes. You are limited in the number of section offsets (5) you have to control the chine lines though this seems enough for small craft.  Also the stem line is shown as straight segments between each chine.  In other words if you want to have a curved profile at the stem you can only approximate this in Hulls.

Design process:
I suggest that its worth working in Hulls until you have the hull shape complete in the sense of meeting your functional requirements for the hull.  The final fairing (including a rounded stem), plate development and internal arrangements can be tackled using different tools.

Dinghy 1.0 linesplan

With help from two excellent forums:
forum.woodenboat.com/ and
www.boatdesign.net
the linesplan is done.
I'm calling it Dinghy 1.0

Time to get the the credit card out.

Crowdsourcing

I found the answer to "now what?" . . . Crowdsourcing!

Though I think 'crowd' is a little bit of a negative term for a bunch of like minded people with more expertise than me.

I submitted my full design for review by people who know what they are talking about.  This thread all about my design is an amazing example of how the internet makes you smarter:
http://www.boatdesign.net/forums/boat-design/ready-design-review-37954.html
All it took from me was the humility to ask for help and the desire to learn - easy and powerful!

Obsession and over-confidence

Any new venture requires an element of obsession to succeed.
So after going to the Hobart Wooden Boat festival I've become obsessed with building a boat.

With growing over confidence the process went something like this:

1. First Mate saw the CLC ply kit boats at the festival and said "honey pie can make that".
2. I researched all the kits from various suppliers
3. I researched all the online stock plans
4. I found free boat design software to play with
5. I knocked up a design that I think is great but of course have no idea what I'm talking about.

So now what?