Copying a hull.....

[frozentripper]

Fuzzy memory... IIRC how to take the lines off a canoe hull create a table of offsets was described with pictures in the first edition of Canoecraft, Ted Moores... published 1983. But not in the second edition. The first is in the library but it's closed because of the COVID mess. Possible to reserve which will take a few days to check fuzziness of memory... or maybe someone who has it could check to see if the info is actually there or not.

Again IIRC, Rolf Kraiker has done this on an old canoe, the Richardson (?)... his website Blazing Paddles seems to be gone, maybe contact by email... rolfkraiker@gmail.com

 

[scratchypants]

I just did that on my current build. I guess how you take the shape is pretty dependent on how you intend to "modify" the shape after you get the measurements. The build is here: https://www.canoetripping.net/forum.../105054-light-weight-solo-tripper-build/page2

I wanted to have a table of offsets in Excel to work from, so I took measurements that gave me the offsets ... having the tables allowed me to adjust curves, modify shapes to see how everything would fit together.

So I think the question of "how" you intend to make your mods will determine how you take the shape, either directly by preparing forms from the donor boat or taking measurements and creating the offset tables.

If you decide on the offset route and have questions, I will try and help as I can.

Brian

Yours was the thread I was thinking about, Brian. This post is where it begins..

 

[Boatman53]

You are correct Frozentripper. The first issue of ‘Canoecraft’ does talk about designing your own and taking off lines. The taking off lines is a single page and basically uses pointy sticks glued around an outside rough pattern to take the shape. Whatever the method used it is only the beginning as all the data needs to be faired up to each other. Sometimes the hull that you might be taking the lines from might not be fair as was often the case with some of the old boats I’ve done.
I’ll look later at some of the titles on my shelf that deal with this subject.

Jim

 

[gumpus]

If you are near a technical college maybe you could entice someone to take it on as a fun project or a graduate thesis.

Step 1 - scan Millbrook Prowler with 3D scanner
Step 2 - create CAD model from scan data
Step 3 - modify 3D model any way you like
Step 4 - print out cross-sections of model to be used as patterns for forms

or just transfer CAD data to CNC milling machine and have it cut out the forms...a fancy milling machine could even cut out the whole canoe for you...or you could just send the CAD file to a large 3D printer and hit PRINT

http://3dscanningservices.net/project/3d-modeling-boat-hull-deck/

I see that some portable 3D scanners are getting pretty inexpensive...like a bit over $200. I bet there are high school students out there that could figure out how to create a modified Prowler.

 

[Jim Dodd]

This is the method I use for making patterns for my Flotation chambers. I wouldn't call it the most accurate. But for Flotation chambers, which get a lot of shaping to ft nicely, it works fine.
For a Hull ? I like Boatman 53 method ! Somewhat similar.

 

[Boatman53]

Well I really dislike not being settled in. Turns out a lot of the books I was thinking about are still in boxes from the move. I really need to build more bookcases this winter. One I did find is called ‘Ship And Aircraft Fairing And Development’ by S.S. Rabl. It is an excellent book complex things described simply. I’ve learned more from this book than any other.
Off the top of my head there is a book called ‘Lofting’ by Alan Vitses, I might have the last name spelled wrong. There are more but I’ll have to get back to you on those.

Jim it looks like you use the dividers horizontal where as I swing an arc. Then when transferring back to a pattern I swing the same radius from two different points on the arc as scribed when taking the lines. Where those two arcs intersect is the same as the original point. You can see the arcs on my cardboard pattern. I’ll do a pictorial tomorrow. It is very efficient and accurate.

Jim