Complex Surfaces for Boat Hull

I’ve been busily modeling a boat. I have the skeleton laid out and all the important components except the most important one: the hull. I got the sides and transom (back) done, but have no clue how to go about laying out the bottom.

BTW, I’m certain there are errors in the layout of the skeleton. My goal here is to have a design that I can a) share with someone so they can bid on construction of the hull, and b) hand it off to a professional drafter who can make proper cut sheets for a CNC. I’m no engineer.

To that end, I need advice on how to create the complex curve of the boat bottom. Where there are flat surfaces (transom and portions of the drive tunnel), I was able to indicate the 2 mm thickness of the metal. Elsewhere I don’t know how to accomplish that.

Thanks for whatever help you can provide.


The shape you have is quite simple, so you can create the surface just using the Line tool.

It’s hard to imagine it without seeing your framework to follow but I think I would start with grid sections following the frame and use the sandbox drape tool similar to making a 3d site topography from topo lines. If you need to accurately show thickness throughout the entire hull then this might not be the best way to go. This might be a great project to model one half of and use the fancy new flip tool.

I left a link to my model in the post. Did it not show up?

This kind of thing would be very tedious at best with SketchUp Free. It would be a whole lot easier with SketchUp Pro. There are some extensions that would help you develop the shapes of the surfaces from the half-breadths and waterlines or other info that you would have.

The link you posted doesn’t give us access to your model. It’s just a link to the viewer with your model but we can’t do anythng with it.

Just use Line and you can create that surface

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Thanks! As a visual learner, this was a perfect way to communicate what to do. I’ll give it a shot.


Sounds like you’re all set. Hopefully it’ll get you close enough.I did a little part of it using Curviloft to develop a smoother surface than you’ll get with Mihai’s process but maybe it’s not needed.

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Thanks. I’m going to see what I can achieve on my own. If it doesn’t work out, I’ll cry for help. :slight_smile:

It turned into something of a hot mess, but suffices for what I need. Thanks for everyone’s help.


Looks as though you have duplicate faces, and a lot of reversed (grey) ones.

Worth correcting before you go further.

Or upload the model if you’d like someone else to look at it and advise.

3C Electric Runabout.skp (8.6 MB)

Here you go. Feedback greatly appreciated. Also, a related question, is there a straightforward way to create an exploded view of my model?


Have you tried using flat panels and then bending to shape as in building a stitch and glue boat. This would also work for a lapstrake or clinker type hull.

I apparently don’t know how to do that. Note that the centerline of the boat has a complex curve in the bow, then a perpendicular curve around the aft portion of the keel where the tunnel is formed. And there’s another curve along the bottom of the freeboard.

I don’t think there is an easy way to do that in the web version. It involves drawing a lot of geometry. There are extensions to do it, but the web version cannot run extensions.


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