First of all, "overthinking" is a really good thing in boat building.  Keep it up and ask questions when you have doubts.

Regarding the puzzle joints, what you propose would be the fastest but maybe not the best.  When you glue puzzle jounts together, it is easy to end up with the joint not being flush.  Structurally, small errors are not a big deal because they can be sanded flush, but this will be a consmetic issue (sanding through a layer of ply) if you are going to varnish.  Doing the joints one at a time will decrease the chances of mis-alignment.

As an alternate approach,  you could use CA glue on the pussle joints to lock the pussle joints in place flush before covering with glass.  This is a technique that shows up in some of the newer CLC build manuals like the S&G PP.  The picture below shows the entire deck of the PP held together with CA prior to fillets and glass.

 As a first time builder, I might suggest that you work serially on the two boats instead of building them in parallel.  That way, when (not if) you make a mistake, it will be on only one boat and not both.  Your learning curve on the first boat will be HUGE.  

Wolfe,

As Mark says, your proposed method would be faster, but I agree with him that for a first-time builder it might not be worth it, especially since you're only going to save a max of a day or so.

I built my WD12 12-13 years ago and here's how I glued my panels:

Spreading out on the floor gave me lots of room. I used polyethylene sheeting sold at DIY stores in the paint departments as painter's tarps. It's cheap, much stronger than wax paper, epoxy absolutely won't stick to it and you don't have to worry about possible wax contamination of the epoxy joint or surface. When the epoxy hardens, it peels right off and you can re-use the piece again.

I'm going to respectfully disagree with Mark's suggestion that you use CA glue. I've tried it a few times, but it never worked out well for me. Maybe I did it wrong or had the wrong stuff, but either the pieces didn't hold together before I could epoxy them or the epoxied joint broke after curing because of the embedded glue. I ended up having to remove all the contamination and reglue the joints with only epoxy/woodflour mix and then they stayed together. Either way, I'm not recommending it to a first-timer.

Congrats on 35 years and a pair of boats is a great idea for a present. You'll have fun building and boating for years. My wife's not a builder, but she's been happily using the boat I built for her for 15 years now. She has a CH17, faster than my WD12, which is just the way she likes it.

In case you're interested in what else has worked for me and what hasn't, I have some web pages devoted to building my WD12. I tried to concentrate on stuff that wasn't in the manual. Sometimes I did it a little differently than the manual. Some of the changes were just different accessories, like stainless steel stud mounts instead of through-holes for the footbraces. Others are just doing things in a slightly different order from the manual, like not attaching the coaming until the deck is all glassed and sanded. Have a look in case there's something there that would help you out.

Have fun,

Laszlo

   I would suggest that you spead them out instead of stacking. If you stack and a lower scarf start sliding apart on the bottom you'll have a hard time adjusting them.

As always, good words by Lazlo.  Especially the part about keeping Her Royal Highness, Princess Admiral of the Fleet happy!  I have found that I can build anything I want as long as about every other build is something that she wants and will use.  I just started her Kaholo SUP.

One point that I left out of my first post is to make sure that you thoroughly label all of the plywood parts, including which side is inside and outside.  Without labels, it is easy to make a mistake.  I have a freind named Mr Dumbass who occasionally shows up when I am building.  He glued one set of side panels on my Ch17LT so that the bow pointed up and the stern pointed down.  The same guy beveled the wrong side of one of the side panels on my Shearwatere Double.  I now label everything.  I prefer that sticky green tape over pencil because a barely visible pencil mark will become very visible after you glass over it.        

 Wow, thanks everyone on the suggestions. I think I will glue up on the floor. I understand what you were saying about the CA glue but will go with the epoxy, mainly because I already have it with my kit. I got my wife the WD10 and myself the WD12. I think I will paint the hull on both kits and only painting the bottom panels. I will use the stain on the deck, sheer panels and side panels. Please stay tuned for more questions. I am a perfectionist and really take a lot of pride in my work, that is why I go over a step 20 times before I actually do the step.

Planning to paint your first boat is a very good idea.  My first build had a couple of cosmetic errors that would have been pretty obvious under varnish.  Build #2 was varnish worthy.

I have used stain on two boats.  The use of stain adds a level of complexity that I would not recommend for a first build.  If you still decide to go that route, you must stain the wood before it is ever touched by epoxy.  Read this:   https://www.clcboats.com/shoptips/finishing-tips/staining-your-kayak.html 

I beleive that Sapelle is standard for the WD decks.  You will not want to stain that because it is beautiful as isd.

If you do decide to stain, make up some samples so you can see what the stain really looks like when applied to Okoume.  Luckily I followed this advice prior to building our SWD.  I had originally wanted to stain the hull yellow, but we found that the yellow Behlin looked like dog pee on Okoume.  We decided on cherry which matched the Sapelle Deck.

Bottom hull panels for the SWD stained and precoated with epoxy prior to gluing puzzle joints.

Close up of Sapelle deck

Sapele is a $40 option over an Okoume deck. On the other hand, the stain is $18/pint plus shipping, handling and tax. Then there's the effort of doing a good stain job and preserving it through the glassing and finishing process which easily makes up the other half of the price, if not more.

Sapele also has a nicer grain pattern than Okoume, no matter how well the Okoume is stained.

In my opinion, if you want a reddish color, Sapele beats a stain job for cost, effort and final result.

Laszlo

My bad!! I meant to say varnish and NOT stain. Now that I made that mistake the stain seems to make a very nice finish to the boat. My WD12 has the standard deck while the wife’s WD10 has the up grade deck. I guess my only option is to buy another kit after these 2 are built and go the stain route!