How'd Chappelle take lines?

I need to take lines of a boat that is neither plumb nor level, and it seems like all methods rely on that being the case. I know Howard Chappelle took the lines off a lot of old rotting hulks. Does anyone know how he did it? Or have a good was to do it? I hope I'm not beating a dead horse.

 

He did what he could. Sometimes he just guessed as well as he could.

 

I’d probably use two lasers and get them lined up as good as can be bow to stern and start plotting points on paper.

Someone here may know of a computer program you can use. Sorry, I do not.

The deck would be assumed level somehow, depending upon the boat. So, you may attempt to reference it and establish the keel centerline. I’ve not done it, so I admit my reply is my best guess at how I may attempt it.

 

Use leveling laser to create vertical laser lines and use washable paint for these cross section lines and take a picture from stern and bow

 

Yes the shapes can be guessed just watching few times and checking hull lines drawings of similar hulls

 

Absolutely wrong. Chappelle used the conventional traditional methods. First set up four square corners and laid strings to create a plane for reference. For the strings to be on a plane you must check the diagonals with strings, which should barely touch in the middle. Make the plane parallel to the waterline. Then, depending on the size added morestrings in between if needed. Finally, used the strings as reference to take measurements and create a table of offsets. Instead of strings sometimes straight edges can be used with similar results. The offsets are then lofted and faired. Ideally take measurements from both sides and average them.

 

Reading between the lines I get the feeling that levelling the boat won't be an option and that does complicate things a bit.It might help to try to establish the angle at which the boat rests in both the longitudinal and lateral senses and that will need a bit of trigonometry.It might also be wise to get numbers for various points since the hull may well have twisted or sagged.It shouldn't really matter too much as long as you can establish a reliable set of reference points and you can tidy up the drawing at your leisure.For suggestions of how to proceed,there is a section in one of John Gardner's books devoted to his way of doing things and since he knew Chappelle there is a good chance that they would use similar methods and perhaps establish a system that made it simpler in the field.A few years ago there was a quite extensive article in the British magazine Watercraft by a designer who has taken lines from boats and then created lines of the hull as it probably was before settling on the various supports around it.Back copies may be available.Gonzo's point about measuring both sides is a very good one.

 

I have tried to do replicas from sailboats since few years to see the hull lines and compare and just did and uploaded these the last month while Shearwater yawl, clubswan, etc are few exceptions of complicated hulls these are mostly accurate replicas made without hull lines drawings

And hard chinned pictures are somehow easier but i also check every picture of the sailboat in hard stand or lifted by crane

 

Ships were built on inclined ways and slid off of them to launch. a wedge shaped inclination board was used with levels to find level and plumb while fitting out on the ways.

 

There are laser scanning techniques for 3D printing that provide accurate "shell" data but that's all I know of the subject but suspect it would scale fairly well. Gonzo's take on the situation seems to answer the original question quite succinctly.

 

Thank you everyone for your replies and advice. I have a better idea of how to take the lines now. I definitely can't make the boat level or do anything that could damage it. I have attached a photo of the boat just to show what I'm dealing with.

 

I forgot you could find a flex memory rod and take the lines with that and then using a pencil over a large piece of cardboard to make hull lines every 300mm aprox more lines in the bow because more curves there

 

Looks like a worthy project. Scanning/LIDAR/photogrammetry would be options on the exposed side, once the earth is removed from the keel. You could consider making a large lightweight frame amidships and chase it with a smaller frame to take the would be vertical dimensions at the hull at each station /frame.



Edit: you could also use tick or joggle sticks from the dark blue frame to the hull and transfer the points full size to paper without dimensions.

 

The laser approach is a good one but it's gong to transfer damage and errors as well.
No idea who the designer is? A one-off perhaps.
Too bad you can't acquire the original plans.

 

With This 3d printed memory rod inside a hose you can extract the lines easily to draw them or taking pictures