MikeyL I'm not familiar with the CY you're building but it's a common technique with stitch'n'glue to go back & loosen or replace stitches when you find you need to move panels that are held too tightly when some may have been maybe tightened a little too much early on.

Or add your own if necessary when you find there's a gap you can close by adding stitches that don't have pre-drilled holes where you'd like to have them. 18 ga. wire's really close to 1.0 mm dia.; it's a #56-size drill that makes right-size holes when needed, or 3/64" if number drills aren't easily available.

Small gaps - on the order of 1/8" - are easily filled with thickened epoxy later on if you find they're just unavoidable. Yet I understand how it gives a builder reason to pause in their progress, particularly if theirs is a first attempt.

Lastly I have to ask if you're not mistaking the CNC-positioning tabs with the shorter ones meant to go into those slots? The bigger ones ought to have been removed before assembly, they're simply artifacts left from the machining process so parts don't shift position while being shaped by the cutters.

And having just looked at the CY's product page I see it's a lapstitch design so be sure the panels that have rabbets cut into their inner edges do overlap the tops of the panels lower down! They're meant to, otherwise they won't form the laps that later get filled with thickened epoxy that 'weld' everything into the final shape the design features. 

   Thank you, SPClark.  That's helpful.  I have sanded the machine tabs off, so will loosen a few of the wires and proceed.  First build so lots of self doubt in the process.  

Yep, first time for anything's got a lot of 'Leap of Faith' moments to get over. (I'm putting shocks & springs on the back suspension of my MINI Cooper today, had one of Those Moments when it came time to deploy a spring compressor.) Admittedly, the Waterlust I started building two years ago last week was my first S&G attempt. It turned out very well thanks to contributions from others here in the early stages.

When I saw your post earlier, noting no replies, I thought perhaps my contribution could help you get further along. That's why this forum is here after all, isn't it? You run into things your prior experience won't help with, let us know here. We'll do our level best to get you back on course.

That Chester Yawl's a lovely design BTW. I wish you many happy hours both a'building her as well as putting her to good use once she's launched. Yoiu have any luck posting pictures here I'll enjoy looking at 'em!!

I know that your post and immediate challenge is from a while ago, but your situation is familiar. I completed my CY build a couple years ago but it required a couple years to complete, partly due to family obligations and partly due to obstacles like the one you encountered. 

Yes, loosening wires to enable the insertion of pieces is common. I found that bringing a second person in on the process helped a lot. It helped in two ways - having a second set of hands allowed for some pushing and pulling from different angles at the same time - and having someone to discuss different approaches with was quite helpful through the process. 

Conducting one of these boat builds s a risk. You have invested a couple thousand bucks and substantive time. Most of the time, you cannot just run to the hardware store or Home Depot to get a replacement board or part if you screw something up. You put a lot of trust in the manual, but the CY manual is dated and definitely not perfect. This forum can be a big help. 

Hope that your boat turned out well. All the best!

DaveJ_NH