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First Things First

So where and how did this project start? I've always had a love of cobles, and have wanted to make a perfect scale model and possibly create a kit and or GRP hulls to offer an alternative to the Northumbrian hulls from Orion Mouldings. As previously mentioned, the full size boat was measured while she was out of the water having an extensive makeover and a few hand drawn profiles evolved from this. I then heard about a program called Freeship which was, what is now delftship. Freeship allowed more than the free version of delftship does such as the exportation of developed planks and what not... I found a tutorial on one of the model boat forums regarding freeship and I decided to put finger to touchpad and start designing.

Those of you who remember the old build of this from a few years ago may have noticed I have began a complete re-start of the project. It simply was torture trying to create new planks and life got busy during that time when the other half became pregnant. The project was burnt in the garden one day when I had finally had enough.

Starting The Build

Freeship is a coordinate based program where 3 axis can be controlled. When you change one thing, you have to change the rest! Because of the nature of how a coble is built (clinker) construction, freeship does not support this feature and some clever points inserted could be used to do clinker but it simply wasn't worth the time to do this as further modification would be needed on AutoCAD anyway.

After the destruction of the last project, I mananged to get my hands on a very primative copy of a table of offsets for a 19ft coble. I converted these to decimal and input this data into freeship. I came up with something like this.

A very nice shape you must admit, sadly with curved planks due to freeship's limitations.

I will take this opportunity to apologise if some of the details of this build are a bit sketchy. I am retrospectively writing this and cannot remember certain things from nearly 3 years ago.

I still wanted the jig system in order to lay the planks onto.

I imported the basic 3d shape from freeship into Turbocad and scaled it up slightly to roughly the size of a 33 footer. A boat of this size would normally have 10 planks but sadly 7 will have to do. I then drew a 3d frame around the hull with certain intersections of where the shape would be sliced into sections. This then gave a rough outline of the shape in which I could then begin to manually create notches for the planks.

To test the concept of lofting planks over this shape, I quickly assembled the frame albeit in 3d but with no thickness which would make things easier.

As you know, the planks overlap and this meant a polyline had to be added onto notched frame which overhung the next one.

The were then individually selected.

The loft command was then used to form an object based on the trends of the selected notches.

And in colour.

I decided to loft every plank and this is the result.

The bow is missing because the curve of the stem is essentially one object and many hours then had to be spent creating a duplicate curve and slicing it at precise places in order for the loft to work. On the real boat what im trying to achieve is this.

And on CAD...

I then began to rotate the objects in order to connect them to the base of the frame in which had already been drawn, based on the measurements of the sections which were sliced out.

Everything was designed to interlock to ensure the thing was square and perfectly aligned.

The completed frame in 3d.

Here are some rendered images of the frame.

You now may notice the stem applied to the model. This is slotted in to the frame to secure it. The plan is for the the ram plank to be installed first and slid under this and all glued into position.

The stem issue was finally solved and here are some lofts of the planks locking into the stem.

The planks themselves leave a lot to be desired.

And all rendered as an example...

Obviously the plank shapes are all over the place due to turbocad's limited lofting ability. It simply doesnt understand what im trying to do. Even if it were perfect, turbocad doesn't have the ability to flatten or 'unroll' the 3d planks into a 2d shape for CNC cutting.

I tried the original freeship 3d hull shape on the frame and this is the result.

Very close you must admit...

 

 

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©Dan Walker