Often the reason is that the faces in the lower part are smoothed, and in the upper part the edges are hidden but the faces are not smoothed. When you try selecting the surfaces, the smoothed area behaves like a single face while the unsmoothed bits sekect separately. Without seeing the actual model this is my guess.
These edges are probably smoothed.
Try View Menu → View Hidden Geometry.
Or, attach your skp file to a post.
You could probably use the eraser to smooth or hide lines, you also have a lot of wrong facing normals.
Are these profiles?
personally, this raises my eyebrows. Sure, part of the ship’s line could be hidden, but this ? the bottom of a simple cylindre ?
do you, by any chance, have a “ground” active (I know, it should be more of a sea). By that I mean a plane that represent the level 0 ? either a physical one you added, or one in the style panel ?
Because here, in this case, it would explain why the profiles stops appearing, simply because technically, if your model is partly below this ground, it’s not “cut” by it, therefore no lines or profiles are actually created.
Yes, there was a ground active, you saw that correctly. Wasn’t the reason the bottom of the ship was not showing though.
Thanks guys, I unsmoothed some of the edges with the eraser. The topic can be closed. 
It would help us help you if you’d share the .skp file.
Could someone open this again. I am new to the forums but have been using Sketchup for a few years but this is a new problem I have come across. The edges appear to be smoothed or hidden but when I troubleshoot those issues they don’t resolve the issue. Edges are on profiles are on and everything is unhidden and not smoothed. I could really use some help its getting very frustrating.
If you switch ON the Hidden Geometry settings what do you see ?
they’re not there. they are not hidden. I can click on them and they are the highlighted in blue.
well, you’ll have to share a file with us if you want an accurate input…
edit : oh ok, you’re talking about your issue here
let’s avoid dispersing the discussion.
hush. i’m new here. trying to navigate how this works.
I had this problem too. The only solution I could think of was to export the troublesome part of my model as a 3ds file-type and then re-import it. Lines were all present when re-imported. Troublesome file is attached.
Troublesome Road.skp (479.3 KB)
Incorrect tag usage.
Turn on Road tag and they will appear.
But you have mixed tagging on raw geometry, all raw should be untagged and only Groups, components etc should be tagged.
Or you can just turn on ‘Road’ tag and then set all edges ‘Untagged’.
Darn it. Should have spotted that one. Thanks.
I never use tags for raw geometry, but let this slip away from me. I’ve solved this problem before but somehow forgot to check this time.
