Curves from old boat plans needs to be surfaced, will this method work?

I have just put together the 2D curves from the boatplan of Hurley 22 way back from the 60s, and I now want to make a surfaced hull out of them in Rhino, so I can start modify my boat to make it seaworthy for the roaring fourties.

I cannot surface the hull with the “loft” function, it goes bananas, and I think it is because the curves are not aligned on the same axis.

Here is a picture of what I think is a good solution:

So I basically want a function that renders my boat in curves in just this axis, from portside to starboard. Then I can use the “loft” function to get a nice surface of the hull shape.

Do you know if this is possible or do you know another solution?

Thank you in advance.

Here is my blog about my project to sail to Argentine with this Hurley 22.

Most Sincerly
Oskar Huledal

Your image is not visible.

I frequently use the Patch command to create boat hull surfaces from sets of lines. It does require some experimentation. I usually create an initial surface using just the edge curves, and then use that surface as the starting surface in Patch.

Rebuild your sections (stations) to all have the same number of control points before trying to loft.

Ok, I will try the Patch command. It does work even if the lines are not connected to each other? The image should be showing up by now. Thank you for the reply.

It sounds time consuming. What do you mean with stations? I failed to post the image of my idea, perhaps you got it anyway, now it works. Have a look, and thank you.

Now that the buttocks lines are visible in your image, I would create plans on which your desired sections would lie. Then you can intersect each station plane with the buttocks lines and you will get points. The use Interpret Curve to click on each line from sheer to keel and get half sections. Do so at each plane and as I mentioned earlier, rebuild each new half section that you just created to have the same number of control points. Then you can loft them and get a surface that you can point edit to get a better fit to the stem.

Here is a hull showing sections at 27"station spacing in red.

In marine design, sections can be in any plane, and stations will be on the yz plane the ones I showed in red. I think that is what you indicated that you were trying to create in your image. Buttocks are on the xz plane and I have shown them here in blue and it looks like they are what you have to work from. Lofting a hull in that direction in Rhino will be harder.

Here is an example of how I use lines plan to model a hull in Rhino that might help. Hope this helps.

Thank you for the quick reply and all the images! I will try this out tomorrow, now I need some sleep.

We will be in touch.

Oskar Huledal

Thanks Jody! I have now finished the boat hull in sections hull and up. I am happy with the results, although the hull did not align perfectly with my curves, do you know why?

I also want to make the hull as thick as in reality to plan the interior, is there any function you know that can do this?

Best Regards

Very good progress.

A few comments/suggestions:

Did you create new curves based on points from the old curves? If so and you used InterpCrv or CurveThroughPt? then the new curves will pass through the selected points. But if you used Curve the new curves will not go through the selected points. The selected points will be used as control points which are generally off of the curves.

There is a radius between the hull sides and the transom. Is that intentional? I always create the transom as a separate surface.

OffsetSrf is the simple way to create an inner hull surface if the hull is constant thickness.

I used Curve through points when it was necessary, always when I wanted a direct connection.

You are right, I failed with the transom. Right now I’m dividing it like this:

How to surface the transom separately? And how to glue them together, without losing the exactness of the boat plans? It gets so easily distorted using loft.

I discovered the reason the hull surface was not aligned with my curves was because of the “loose” style when I lofted, I changed to “Tight” and it was better. Still distorted though.

For the transom curves shown I’d use the Patch command to create a surface. Also create the hull surface up to the transom. Then extend the hull and transom surfaces if needed so that they intersect, and trim each with the other.

Old linesplans are notoriously different to the as-built vessel. If you are planning on any digital fabrication, cnc cutting of panels etc, then you will need to measure the vessel as-built.

Good luck with the project.