Adventures in Lofting

Evan Gatehouse wrote:

> Steve Lusardi wrote:
>
> > No computer will ever replace this task,
>
>> even big ship yards still must bulletproof the table of offsets for
>> CNC cutting machines to be accurate.
>> Steve
>
>
> Steve,
>
> Maybe a decade ago this was true, but in the real world of today's
> shipyard, the cut files are all done on computer, the plate is burned,
> and erection starts the next week. The loftsman is a dying breed.
>
> We (commercial naval architects) seldom provide tables of offsets any
> more; just send 'em an IGES file of the 3D hull surface, or we produce
> all the steel parts in house. No lofting required.
>
> Evan Gatehouse


While the drawings look small, they are drawn in full scale.

Actually, sometimes much larger than full scale.
When zooming in to locate a point between a waterline and section
I may be as much as 100 x magnification.
Trying for .01 inch resolution.

Can't do that on the floor.

But that's the way it's done these days - and why the parts fit
so well (hopefully!).

Richard

cavelamb himself wrote:
>
> The top pic, the basic lines layout was found on the web.
> The others I've either taken from books and traced, or used the
> published offsets.
Sounds Like you have found effective sources.

>
> But I'm not intending to sell anything.
> At least not at this stage.
> Just trying to learn how to do the work.
Learning is always good,
>
> Tracing sucks.
> Terribly inaccurate since he lines look like they were drawn with a 3"
> paint brush.
>
> Makes fairing a lot harder than necessary.
> And once faired, there is no telling how accurate the generated shape is
> compared to the original.
Just so you know.... The final hull and foil shapes of a number of boats
out there don't always have a lot in common with the designed lines.
(That's what I often have to fix.)
>
>>
>> How would you get the image of the frame stations or buttlines with
>> the cradle structures in the way?
>
> My trailer has very little to interfere with the laser.
> This CAD package used a splined curve.
> Outta fill in the small gaps ok.
Prolly work, just watch out, computers can be real stupid sometimes.
>
> At least it would be cheap and easy enough to try.
Actually, it sounds like it could just be a lot of fun.
If you could get about a box full of those line creating lasers and set
some up as waterplane, some as station and some as butts - you might be
able to reverse engineer a hull shape pretty effectively.

I'm interested to see how it works out.

Matt Colie