Hehe
It's the normal way of naval construction ! Some many lines to join :)

You can do that with MoI not now easily now because you can't load the image in background
But with these little plug http://home.insightbb.com/~ryanvm/tinyutilities/vitrite/
you can have your window with transparency !
So open your image in one window launch Moi & Bon Courage :)

If you want a complet tut for make your boat with a Nurb modeleur go there :)
http://www.3drender.com/rhino/boathtml/index.htm

Else if you want a naval boat modeler
the open source Free Ship is excellent !
http://www.freeship.org/

Yeah, these kinds of undulations are frequently a problem when you try to use a larger number of sections.

It's annoying because you want to add more sections to create more control, but since the surface is forced to go through each section there is sort of a "ripple" effect that happens.

You may try to use a fewer number of sections.

Another thing you can try is using loft, with the Loft Style = "Loose" - this will make a surface that is just guided more gently by the cross sections instead of being forced to go right through them, it tends to build a more gentle surface.

If you can post the .3dm file, it could help in suggesting some tweaks to make it better.

- Michael

Michael,
Yes, thats exactly the issue. Since the line points vary in position it results in excessive numbers of points in the object, virtually impossable to control manualy.
Lofting loosely with the min of stations gives the best result for sure, atm. I notice that re-creating the surface with a uniform simple UV structure is the solution Rhino has taught nurbists to look for. Thinking of adding that in a future iteration?

Pilou,
Thanks for trying to be helpfull.
Yes, obviously, that is the rhino tute I was following. You can see that by the BG image I posted.
Yes, the app and transparency combination Michael suggested is very helpfull for the moment.
Yes, Freeship is another way to create a hull in obj form. It's much better suited to creating simple planar based hull shapes though and if I resort to another app, why not XSI or Rhino? The exercise was to work through a rhino tute with MoI and thereby improve my nurb-flow and at the same time see what aspects of MoI function were hi-lighted in the process.

Cheers
Spinner

> I notice that re-creating the surface with a uniform simple UV
> structure is the solution Rhino has taught nurbists to look for.
> Thinking of adding that in a future iteration?

I think that you're referring to the Rhino "Rebuild" command. I would like to add this in at some point, but not sure of the schedule for it yet, though.

But it kind of seems like a sort of "hack" to use something like this to smooth out results... It would be better if there were smoothing options built directly into the surfacing tool itself in some way. It may be a while before I'll be able to explore that in more detail though (although the "loose" option in loft is one such thing already).

- Michael