Weird issues with faces/surfaces


I’m modeling a radio-control sailboat from 1949 and am having issues with certain faces.

To be clear, I’ve drawn over an image, but this issue shows regardless if I am showing or hiding the image.

On a couple faces, if I click them, only portions of the face gets selected (turns to blue dots), but the rest doesn’t select. Is it something with hidden geometry (which I don’t understand at all)?

As I was drawing the model, it all was going well. And then suddenly this stared happening.

Any help is appreciated for a rookie. Please talk to me like I’m 7 so that I can understand what to do. Windows 10, NVIDEO GeForce GTX 960, SKP2017 pro.



Turn on Hidden Geometry in the View menu. You will probably see that the surface is divided. You can try erasing the hidden lines. If the faces disappear you might have edges that are off plane.

If you share the SKP file we can give you more assistance.

I think if you turn on “show hidden geometry”, you’ll probably see dashed lines on the edges of those regions. A nearly flat surface that got fractured somewhere along the line.

Thank you. So how would I put all the edges onto a plane?

When I double-click the part, it shows hundreds of lines and such.

I’m trying to upload the SKP file, but it keeps saying that it’s too big. I’ve deleted EVERY single part of the entire boat except the one keel part, and it still won’t go under 5 megabytes. It’s obviously something with that one part.

Here is another picture after I’ve deleted everything else, and have double-clicked the remaining part.

Go to Window/Model info/Statistics and click the Purge Unused button, then save and it should be a much smaller file.

As Box said, purge unused stuff from the file. Deleting from the model space doesn’t mean it’s deleted from the file.

As for how to flatten the shape, I would erase all those weird hidden lines. Then you might able to fill the face by tracing a few edge segments. If that doesn’t work, it’s safe to assume some misalignment. You could fix it by moving vertices along the perimeter but this could be a lot of time consuming work. I would fix the alignment by projecting the edges onto a face. There’s an extension called Projections available from Sketchucation that does just that.

Thank you. That worked to reduce the size dramatically.

Riptide Test Copy.skp (93.4 KB)

What is uploaded is simply a test version of the part that is giving me fits.

Riptide Test Copy.skp (80.9 KB)

I exposed the hidden geometry and erased it leaving just the perimeter edges. Then I traced one segment with the Line tool and the face filled. From examining the coordinates of a few vertices, it looks like you have all the edges on the same plane. Not sure what step in your process caused all those hidden edges but it was easily cleaned up.

Dave R,

Thank you very much! I tried the same technique you talked about on the same test model and it worked. I’ll now try it on my actual model. If it works… then thank you so much!


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Hi again,

So I tried that with my actual model, and then saved. As soon as I returned to it, all of the hidden geometry had returned as if I never deleted it. Ideas?



Signed up for SketchUcation, and downloaded the Projections plugin, but can’t seem to install it. Tricks?

Never mind… I figured out how to install it. Now how to use it…


How about this?

Thank you! I meant to reply a couple days ago. Not sure exactly what I did, but after several variations I was able to make it work. I projected the keel onto a plane successfully. It all works well now.

Thank you again!



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