Chine fairness in boats

I am not posing a question as much here as i am documenting an issue I've come across trying to design panels for stitch and glue boats.

Something i have found is that seemingly negligible humps and divots in a hull can completely throw off the look of a boat. Fairing is always possible but id like to get away from it as much as i can. I am designing panels with basswood and stretching them out to shape. One thing I am finding difficult is creating a fair sweep in the chine and avoiding a pinch just forward of where the sweep occurs. I found that this pinch is most likely happening as a result of wrenching down aft to minimize deadrise more than the panels want (in terms to fairness). The solution I believe is to move the bow point in the bottom panels and where to start your curve in relation to it to have deadrise more or less built in. Now how many basswood panels it would take to get my intended design I'm not sure. But my aversion or inability to use computer software has lead me down this road and I find it quite fun regardless. I have found some math on panel expansion but I think it will be a while before I can wrap my head around it and by then I think I can develop a decent enough intuition for drawing.

I am attempting panels for a small double ended trawler. As someone who has no experience even being on any boat larger than 14 feet i am looking to gain some experience as a passenger aboard said trawler and finding some more litrature on design to gain insight. I was particularly inspired by eva during a recent trip to finns slough and have found a nice plywood design timbercoast 22 that would suit me just fine. While it would be economical to buy plans i am still part way through a build of my own and have plenty of time to muse on drawing and stitching together panels and promptly throwing them in the compost when they turn out horribly.

I would like to add that I have not been commenting on posts and only posting because of my heinous inexperience. And I am finding this forum to be of incredible help in my attempts to design and build boats.

 

You might benefit from reading the section about designing for conic sections in Ernest Sims book on aluminium Boatbuilding.the material is different from that you are using,but the principles are at the root of all designs that use flat panels which are curved to the desired shape.

 

Sam Rabl gave a brief but informative write up about conic projection of plywood that is still relevant. Some people will substitute say 2 layers of 6mm ply instead of one layer of 12mm, even if the panel is "developable", it is just easier to work.

 

I'll check it out, thanks!

 

That's what I need! Thanks

 

Any developable panel has its limitations, you are forcing it past those limits.
Don’t let the material force the shape of the hull.
You may need to strip plank it to achieve the desired results.

 

This is a prospect I've been eyeing. Stitch and glue is fast but clearly limited in terms of shape. Reading gardners stuff now and looking for more info for lofting. If I can wrap my head around it strip planking seems like an enjoyable process.

 

Tight curves even with strip can be difficult. Vertical ply cold moulded has been used on many Vivier designs, faster and more cost effective than strip plank, according to Vivier.

 

An easy way to test panels is to use stiff cardboard. Definitely faster and cheaper than wasting good plywood. If the lines are fair it doesn't matter what the algorithm to describe the curves is.

 

Sam Devlin writes about in his book on stitch and glue technique; that he carves a half hull and presses a piece of card stock on it to trace the panel shape, for a non numeric approach.

 

Yes cold molding has definitely been something I've been eyeing. The most difficult part for me is designing frames that give a fair surface. My first attempts resulted in massive gaps between frames so there's definitely a lot to learn in that regard

Now that is a simple way to do it!

 

What an actual Timbercoast hull planked with plywood looks like.

 

Holy crow. What a beauty, thanks for posting those. Your build?
Edit: just realized YOUR website is where I first saw the timbercoast!

 

Always wondered why my old Waterwitch ketch had such a blunt bow entry, when it could have been like this. Quite the example of what can be done with good design.

 

Nomiddlename, instead of composting failed balsa wood models, that's raw material for a smaller one. Have you tried old methods like steaming, or slow bending where you bend to near the limit, (before cracking), and leave strained for days/weeks, then bend a bit more, and leave strained, taking weeks to take shape. I did it with 4mm ply slowly tortured together, with threadbar, big washers and nuts done up till I hear strain, and leave for a week, and repeat for many weeks, with patience. Make your chines with smooth sweeping graceful lines, rising rearward to stern from about the beam or just forward. Boats with chines are great, except for wave slap noise.
I'm amazed by the efforts of some model makers, with the intricacy, and accuracy to design. Some ships in bottles are incredible.