As an alternative to a printed layout, offsets from a plywood sheet corner or centre line allow for less waste and can be more accurate than some print processes. It is important when springing curves to mark the stave with the length of mating curves to ensure they are the same length. But raw hull offsets? No thank you. Doable? sure, easy? no.

Yes, I've used several sheets of A4 to plot the curved components of my wingsail battens, but when it's the length of a dinghy we're thinking of, then it's time for fewer, larger sheets.

Back in my early days in a drawing office in the '70s, we had a plan copier that worked with sensitised paper. The original, on tracing paper or film, had to be laid on the copy paper, and then both were passed around light source in a roller. The slight difference between the radius of the original and the radius of the copy paper as they went around the roller resulted in an error in the scale on one axis but not the other. Then the copy had to be passed through an ammonia bath to develop and fix the image (ugh), which caused more distortion. I wouldn't be surprised if the pram design's paper print was of that vintage. 

Later on, plan printers fed with computer output had actual pens, and then inkjets and lasers took over. None of them had any scaling issues, it was just the copies of hand drawn originals,

But I have to question your reasoning for not printing on A1 or A0, which would have saved that hassle. The whole point of PDF format is that it is an accurate representation of the document. If I print a PDF on my A4 home printer, I get choices: "Scale" and a box where if 100% is entered, I get exactly that - I've just tried it; and "Scale to fit" where I have two choices,  "Print entire image" or "Fill entire paper" - both of which would result in an unknown scale factor. I cannot believe that a print shop, given a request to print at 100%, would deliver prints at the wrong scale.

The only large format printer I knew of at the time was an hour and a half's drive away and specialised in art/photography and would have been expensive if numerous attempts were needed to get the scale right, and there's 4 sheets. I doubt I spent much more time printing and sellotaping than I would have done driving. I may have been wrong but my own experience as a previously semi-pro photographer was that the pdf had not been created properly, I wish I could find it now to check. Whether or not anyone else built to these plans or had issues I couldn't get out of WoodenBoat Inc. This was a pdf. created from a scan of a set of 40"x30" drawn plans and there may have been an issue with the scaling in one axis, a file created purely from a CAD program would of course be reliable. 

Jan,

Huge congratulations on building such a pretty pram.

Even huger respect for accurately aligning 16 sheets of A4 as you taped them together.

But I have to question your reasoning for not printing on A1 or A0, which would have saved that hassle. The whole point of PDF format is that it is an accurate representation of the document. If I print a PDF on my A4 home printer, I get choices: "Scale" and a box where if 100% is entered, I get exactly that - I've just tried it; and "Scale to fit" where I have two choices,  "Print entire image" or "Fill entire paper" - both of which would result in an unknown scale factor. I cannot believe that a print shop, given a request to print at 100%, would deliver prints at the wrong scale.

And yes, CNC cutting uses the same basic info and the output can be scaled; if you cut at 100%, 100% accuracy is what you'll get. It's just the same as printing, but with a cutting tool instead of ink.

Sure, a CNC kit will cost more than a DIY kit; but as I said, it's for folks who are cash-rich but time-poor, or lack the space/facilities/skills/tools to loft and cut parts themselves. Getting some A0 prints of PDFs done at 100% scale, and pricking the shapes of components through them onto the plywood is a good, less expensive alternative. Thinking back to when Tystie was built in 1999/2000, I remember that David Thomas supplied exactly that, and the hull builders did exactly that. I note in the book Principles of Yacht Design that this is now the norm for professional builders. Why should amateur builders deprive themselves of the speed and accuracy of doing things this way?  

Some observations based on experience building an 11.5' Norwegian Pram;

Beautifully drawn plans came as a pdf to be printed on some US format like 40"x30". I knew I was in for trouble, paper was invented by the Chinese thousands of years ago, and printing invented not long after so it simply must be obsolete in this modern age. I gather they invented some kind of sailing rig too... ;-)

Anyway, while checking out the pdf I noticed that the document if printed at 300 pixels per inch would not result in a printout 40" by 30". The suppliers couldn't understand my concern as they know a lot about Wooden Boats but not much about computer graphics and that 8000 pixels printed at 300 pixels per inch would result in a plan 26.6" high or something like that. In the end I think I edited it myself and printed it on 16 sheets of A4 paper, yes it can be done David T. I used a posterising program free off the internet. The suppliers guaranteed me that two dimensions, one vertical and one horizontal, were printed full size and gave me the exact measurements, so I calibrated to that. If I had gone to my nearest large format printer about 60 miles away I think quite a few expensive sheets of paper and wasted back and forth trips would have ensued. So beware, dashing off to a printer with digital files. And be encouraged that you can do it yourself on A4. Maybe CNC cutting files are immune to issues like this? 

Also worth noting; I had my boat in the water for about two-thirds of the cost of a kit from Fyne Boats for the nearest model they have to my boat, and my boat 1) looks better to my eyes and 2) is built like a tank from 8mm Robbins Elite and should last longer than the kit boat. It is glued and screwed clinker construction, built as if using planks of timber. 

If you buy a kit or get ply cut, you are stuck with what they sell you (more than full price Robbin's ply, compared to what I got hunting around for sale prices, and repurposing/reusing things). I've nothing against people building kit boats, I just still believe more in doing things yourself. The spirit of the whole project is subtly different, maybe not "better" but probably so for many people. 

I still have two sheets of the plans but have lost the pdf, as happens with things digital when you upgrade hardware.