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Hull Lofting Tutorial:

Start: 0
Set the first dxf: 1
Paste other dxf's: 2
Loft profiles: 3
Loft test: 4
Loft Better: 5
Shelling: 6
Full Length: 7
Keel, Mirror & Render: 8

 

 

Background:
The ship lines were created by Dr Allen Magnuson in Feb 2005 using Vacanti Prolines LE. The data was exported in 2D dxf format, then traced in TurboCad Pro 8.2. Hull is based on the proportions of Noah's Ark according to Genesis 6:15. Tutorial by Tim Lovett Feb 05.

 

STEP 7: Full Length


1. Aft dividers for spline nodes...

The aft body lines have been mirrored on top of the fore lines. The best way to avoid confusion is to hide the fore layers and make only the aft layers visible.

The fore line dividers (blue) are not very well suited to the aft hull shape. We need to draw a new set of node dividers. In the fore section we ignored the keel, so we continue this trend and ignore the skeg also. We want the node divider lines (tan colored) to still give 12 points on each body profile (black), so the inner dividers need to be raised as shown below. 

Whoops. I had Workplane 35 active while I was drawing, instead of Workplane "midship" like the rest of the body lines. 

To swap stuff to a different workplane is very easy; (handy hint)

  • Select the stuff > Set the desired workplane active "midship" > Format/Place on workplane

   Swap to workplane "midship"... 


2. The Aft profiles

Now continue to draw station splines for the rest of the hull. Here is the complete station data;

Sta

X fore

Sta

X aft

1

0

35

3089.274

2

90.861

39

3452.718

3

181.722

42

3725.301

4

272.583

45

3997.884

5

363.444

47

4179.606

6

454.305

49

4361.328

8

636.027

51

4543.05

10

817.749

53

4724.772

12

999.471

55

4906.494

15

1272.054

56

4997.355

18

1544.637

57

5088.216

21

1817.22

58

5179.077

25

2180.664

59

5269.938

30

2634.969

60

5360.799

Now carry on, drawing the loft profile splines...

There are similar issues with the lower area of the stem at the stern - problems with lofting geometry in the transition from the transverse profiles to the stem profile. Best to do some isolated lofting and shelling until you get this geometry working. It seems a bit easier than the bow, which could be due to the near hollow in the bow entry.

The final profiles ready to loft...

Do the loft... Is this a problem? NO, it's just the Turbocad wireframe taking a shortcut. Maybe hide a few bits - like the profiles etc. Good idea to puit the loft on a new layer too. Even better idea - save it! (I'm up to "ship16.tcw" now...)

 

Anyway, if you render to wireframe you will see correct geometry...


2. Shell and check

TC decided that an "shell inwards" actually goes outwards here. Anyway, the shell went ok...

If TC can't work out inside and outside, we'd better check... With some loft lines displayed, zoom up...

The test of a robust shell is to see how thick the wall can be before it fails to shell. 

 

 

 


Tim Lovett 2005 | All Rights Reserved| http://www.worldwideflood.com