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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.