Full size Patterns or Lofting
Many designers supply full size patterns for frames, stem, etc. with their plans. Most of these patterns are printed on paper and herein lays the problem. Paper is not a stable medium and shrinks and distorts with moisture.
Mylar on the other hand is more stable than paper under the same conditions but is very expensive. If you want Mylar templates, you are going to pay a small fortune extra for them. I have not met a designer that supplies templates on Mylar at no extra costs.
My personal preference is for lofting. Any boat builder worth his salt will loft a boat and take frames and stuff of that. Although most offsets nowadays are computer generated and very accurate, it still makes sense to loft full size and work from that.
CNC cutting files are the fashion nowadays, and these are extremely accurate, and this totally eliminates lofting, but not everyone has access to such facilities to have their frames and plates cut.
SOME LOFTING HINTS
1. Use a flat, smooth and stable platform to loft and make sure it is big enough for what you need. I used 10mm plates tack welded together.
A fellow boat builder used plywood sheets joined together, but usually a cement floor is sufficient.
2. Use smooth battens that bends smoothly without any hard spots or bumps.
3. Work accurately, keep your chalk or pencils needle sharp - remember, a blunt chalk or pencil can result in serious accumulative errors.
4. Always double check.
5. When drawing a large curve / camber, use help to secure the batten across points or alternatively, uses batten weights.