Trying to Loft

[Anonymous]

Hi Guys.

Am trying to create this }

Cant get the loft to accept the lower rail?

Help please.

Thanks

Malcolm

[James.Youmatz]

Hi @Anonymous,

Can you share your model with me at james.youmatz@autodesk.com and I'd be more than happy to take a stab at it. At first glance I am not sure, but I'll tinker around with it and see what I can come up with!

Thanks,

[Anonymous]

Thanks for kind offer James

File sent

Kind Regards

Malcolm 

[James.Youmatz]

Hi @Anonymous,

I didn't really find the most efficient way to do this, but I did find a way! 

Instead of using that line as a rail, i turned it into a profile. What I did was created a sketch on the YZ plane and then projected that line into my sketch and sketched a line from endpoint to endpoint to close the profile. Then I split the body into half (so I had to separate sides to the loft) and lofted the right half to the profile and then the same for the left half to the profile. This doesn't give the best continuity, but I am curious to see if adding Fit Points into your spline and checking its curvature comb will help. The screencast below shows my thought process:

I am still experimenting with choosing vertices as opposed to faces to loft to, but that is causing issues as well. There are definitely some users on this Forum that are VERY talented when it comes to lofting/curvature analysis so hopefully they jump in too!

Thanks,

[Anonymous]

Hi James ,

I had a go at your route and eventually got the same result , thanks very much, however , its not what i was hoping i would get and this is where my very limited knowledge/ability is showing.

I am trying to get the curvature on the hull to run in both planes , longitudinally , and in cross section . so that i end up with the hull rocker running from bow to stern, but flat in cross section , I

hope the attached shots explain a bit better what im trying to achieve.

Any ideas ?

Thanks

Malcolm 

[James.Youmatz · Accepted solution]

Hi @Anonymous,

So I really don't know that much about boats/hulls so please forgive me if I'm missing a concept here.

I think (with @innovatenate help too!)  that what you were looking for is a flatter top that did not come down to the edge of the model and created a "bowed shape", is this correct?

How we got around this was to create an intersection curve between the flat edge you created as the outline of the hull and the small rail above it. This in turn gave us the shape that you were looking for as a 3D sketch among multiple planes. 

Assuming this, I then went on to try two different methods in my screencast below. The first method is using the lofts in the Model environment. What I did was selected half of the back profile (same concept as the original screencast I created except just using a mirror this time) and lofted it to the vertex at the nose of the boat (I'm sure im using the hull terminology incorrectly!) Then using the rails you tried to use (except using the intersection curve now) you can see it take a better shape.

I used a zebra analysis to show, that although this method was better, it still came to an edge at that mid rail where we mirrored it and wasn't that smooth.

Therefore, I took a different approach (which may not be the shape you were looking for which is why I included both in the screencast) of a smoother approach using patches and patch lofts. What I did in this was to first create an Extrusion from that center rail of the hull. I did this so I can create a tangency on my loft and therefore have a smoother curve when I mirror the patch. Selecting the edge of the Extrusion (make sure it is of the Extrusion and not the Sketch rail! Turn your sketches off when selecting this to make it easier and make sure you have chain select off!) make sure to select Tangent for the profile that is the edge of the patch instead of Free. Then select the intersection curve and the outline as a rail, you will now have the bottom part of the hull as a patch. Mirror that across so you have the full model as a patch and now create a patch across the top of the hull and the back to fully define the region. Then stitch all of the patches together to get a full body. Now using zebra analysis, you will notice it is a bit more continuous. Check out the screencast!

These are just two ways of doing it, and like I said before, there are probably many different ways of doing that. Let me know what you think and hopefully that is closer to what you want! 

Thanks,