A better example needed for Excercise 59 - Canoe, in training manual level 1


#1

Hi all naval architects and boat builders,

I have taken a better look at the canoe of training manual level 1 (exercise 59, Loft.3DM (188.3 KB) ) and I must conclude that it is a bad design. This is a pity, as Rhino is so capable for hull design and fairing. See attached picture showing the bad curvature of the center line.

But besides the curvature of the center line, the function Shell is not working properly and the function OffsetSrf is resulting in a twisted seam.

I propose I make a better example for the training manual which shows that rhino is very suitable for hull design and fairing. Is there any interest in this?

Friendly Regards,
Bas Goris
Hull Design and Fairing
Rhinocentre.nl


First Attempt at Ship Hull
#2

Hi Bas,

Thank you for posting this and putting effort in it.
As we earlier concluded, this Rhino Level 1 training exercise is currently not working well due to new Rhino behavior. Especially the shell command in the tutorial is useless for this specific exercise and that is a pity, as the shell command can be very useful. Also the problems with offsetting the hull surface is not ‘selling’ Rhino to the marine industry.

I do hope that the McNeel Level 1 training representative is willing to edit this exercise with your co-operation.

Keep up the good work!


#3

I agree with you both that the Rhino Marine community could use some ‘love’ of such issues. Surely between the three of us, we can come up with something to address that canoe tutorials shortcomings. Remember that was done a long time ago. Perhaps we should start a new category to include ORCA3D use with Rhino.


#4

Dear Jody,
I do not think McNeel should include third party software like Orca3D in their level 1 tutorial. I can easily design a better canoe with the commands available in Rhino. I will come up with some results soon.
Bas


#5

Good point Bas. I wasn’t proposing to use Orca for a Level 1 tutorial, just that we could possibly have a category here for Marine design and that could or should entail Orca. I look forward to see what you come up with. Start with the basics is a good way to go. I do think that a Orca category here would be helpful though.


#6

Dear all,

What do you think of the curvature of the centerline of my new hull, made by Loft, option Loose.

I am now happy with the curvature of the centerline:


I am still not satisfied, because the _Shell function does not get a good closed solid. And shape of the nose and the camber could be better. See the layers of the rhino file to understand what I did: CanoeCurvesTest3.3dm (1.3 MB)

To be continued…
Cheers Bas


(Pascal Golay) #7

Hi Bas - thanks, I agree that the example, from a boat designer’s perspective, is not ideal, and that in any case shelling should not be included in this exercise. So I am all for havng a new/better example… but keep in mind that this is really just to indicate, for general Level 1 training, how the loft command basically works to combine curves and turn out a surface. Introducing loose lofting would be jumping the gun in this context.

-Pascal


#8

Dear Pascal, please note that the command shell is included in the current exercise 59. See page 173 of the training manual level 1. And loose Loft is mentioned as well in exercise 59 on page 171. So why not? :slightly_smiling:
-Bas


(Pascal Golay) #9

I know that shelling is currently included… I think that is a mistake, myself.

-Pascal


#10

Dear Pascal, see it this way. I can provide the curves for normal loft as well as loose loft, but the normal loft curves will take me much more effort to get to a satisfactory end result. For the people not being naval architects it will not matter, exercise 59 provides the basic curves for the loft anyway. But showing the loose lofting will help naval architects in the right direction. But the exercise can show both methods, providing two sets of curves.
-Bas


#11

I have made another example CanoeCurvesTest4.3dm (639.5 KB), still using loose lofting, where the lofted shell goes beyond the center line. The Shell function is working on this model. Very nice.

Does anybody has a clou why the command _Shell works on this example 4 and not on my previous example 3?


-Bas


(Wim Dekeyser) #12

I’m with Pascal on this one. I feel that it is a bad idea to model something that (some) people will expect to function as a product in a complex hydrodynamic environment in a Level 1 course. The focus here should be on the commands and workflows; not the product.
That said, I agree with Bas that, if one has a canoe tutorial, it should be correct. And I do definitely see that as worthwhile, just not as Level 1.


#13

Hi Pascal,

I have made a new canoe with normal loft for you CanoeCurvesTest1a.3dm (617.0 KB) with an almost flat bottom as below picture shows. I still do not like the discontinuity in the centre line. Any suggestion to get it smooth without using more tricks?


But zooming in the curvature in the bottom shows that even this bottom is not straight, which is the nature of normal loft to me.

Cheers,
Bas


#14

I made a short screencast of my approach to this problem. I think it shows some important principles of modeling with Rhino. I find that you need ‘nice’ curves to start with and most often as few as possible. I also try to understand what a command does best and then I try not to move outside of that scope. Here, what I would say I’m doing is getting a basic ‘fair form’ in the simplest manner possible (which ‘loft’ can readily provide) and then modifying that form locally with methods that retain that initial ‘fairness’. It’s unfortunate that the training manual is rather linearly assembled and isn’t instead structured to jump a bit and bring together some of these more successful practices.

Chris


#15

I also stumbled upon this item while taking the course and after spending a frustrating 1/2 hr. by myself trying to achieve the shelling of the canoe as shown by the tutorial I asked the trainer to look into it. After another 1/2 hr. he concluded that there was something wrong with my “settings” or with the exercise. I still finished the solid the hard way trimming surfaces and joining naked edges.

Now, I would like to protest the following:

Pascal
If the exercise calls for a solid after the shell command, then that is what has to happen. Please don’t play down its importance because is just a level 1 exercise. I paid good money for the course and a statement like that does not sit well with me.

Wim
I know I am quoting you out of context, but here it goes. It makes no difference what the model’s ultimate purpose is. If you design a syringe tip that puts plasma into your body, but because this is just a Level 1 exercise where you might get your plasma channel plugged that is not acceptable to me. I need to know that I can build anything I want with this software and not only inoffensive rubber duckies.


(Pascal Golay) #16

In my opinion, simply adding shelling to this particular exercise (it did not originally include shelling and was not intended to be used this way) was not a good idea. It was just fine to show how Loft works.

-Pascal


#17

It is not very hard to get it smooth but its a bad idea to even try because it produces a degenerate surface. You don’t want a degenerate surface because it will guarantee that the shell command (and other commands) will fail.

Your previous technique of creating the surface so that it goes past the centerline and then trimming back to the centerline is a far superior way to make the shape if you want to continue modeling further without trouble.


What is a degenerated surface?
#18

Costel,

You can avoid the hard way of trimming the surfaces & joining naked edges.

Execute the ‘createsolid’ command… the boat will instantly become a ‘closed polysurface’ :slight_smile:

Sean


#19

Dear Chris,

I love your method. It is a nice combination of two methods, e.g. loft and control point manipulation.
For the training manual we need to find a method less advanced, showing the use of the loft command (with the different options like normal and loose) and mean while show naval architects that Rhino is suitable for their use.

Bas


#20

Sean
I am yet to use this command successfully. In fact I never use it as it does not work, or I do not know how to make it work. Sometimes the object just disappears from the screen and I am being asked if I like it and want to continue. There is nothing to like.

Anyway, coming to our topic, the “createsolid” does not work with my system. Even playing with tolerances from loose to tight does not do the job.