# How can I subdivide and curve/smooth a low poly line without moving the original points

I am trying to create the hull of my frigate by creating latitudinal curves, converting them to meshes, and then joining the mesh lines to create full mesh. As you can see in the images, I am using diagrams from the plans of an actual vessel, and trying to redesign it accurately.

This image is looking directly aft, along the x-axis, to see a cross section of the hull.

My question is this: How can I create the side meshes of the frigate time efficiently, and yet retain the proper curve?" Below I manually created one rib for an example, and in the image below that I subdivided each section and manually moved the points to create a reasonably accurate curve.

Obviously, manually creating and adjusting many curves for the entire length of the vessel would be extremely inefficient. Perhaps I could create a curve, and somehow intersect it with each longitudinal line, or shrink-wrap a curve to them, but I have not yet learned whether this is possible or whether it would create the desired result. Perhaps I can take the low poly line before I manually curved it, and use some modifier to subdivide and smooth it, though it is important that the original points do not move.

not sure if it is the solution but if you quick add faces to your loop and then use the knife project fonction with the side curve and remove the vertices you don't use in the end.

Draw the side section with curve as you did for the front section.

Then convert all those new curve to meshes with command + c Join those meshes with command + j

select the new mesh (the one made of the joined one) and then what you have already done for the front of the boat.

use the side view and go to edit mode en press space to search "knife project

this will cut your mesh where it intersect with the second one

You could try using the Subdivide operator in the Specials menu (W). Crank up the Smoothness value in the Adjust Last Operations popover. You may need to flatten the mesh out after that since it behaves a bit strange sometimes.

If you use smooth on a surface it will behave better. Maybe model your boat low poly and then use Subdivide on the surface?

Another way is to convert the mesh to a Bezier curve with automatic handles. That could be done by selecting in object mode, search (F3) for Convert To and then select Curve. Select in curve in edit mode, (menu) Curve, Set Spline Type, select Bezier. Then (menu) Control Points, Set Handle Type, Automatic.

You can now set the desired resolution for the curves in the Curve Context Properties and convert them back to a mesh if needed.

These methods should not move the original points.