The Uncle John's kits look pretty good, and I know they have good instructions.
My plans did not call for a scarf style joint and I dont think it is necessary. I butted the sides into the bottom and joined it with fiberglass and putty fillets.
The easiest part of the whole build for me was cutting out the wood and temporarily joining the boat. But I do have an entire cabinet shop at my fingertips. The real challenging part was the fiberglass work. I fiberglassed the whole bottom of my boat. The inside joints were a pain, I would do things different next time. On my joints I painted on a first coat of resin, made my putty fillets, and put down my fiberglass tape all before it started to harden so it would all harden together. I would not recommend doing it like this. Next time I will paint on my first coat of resin, and let it harden. Then I would come back and make my putty fillets along the seams and let them harden. After that I would put down my fiberglass tape, dry, and then role on my resin until it is saturated. I did that on the outside of the boat and it was much easier.
I also learned that for the seams the tightly woven fiberglass is easiest to work with. I used that on my seams and used the other thick stuff, that comes all apart, for the bottom of the boat. That seemed to work out pretty good.
I also didnt use ribs on my boat. My plans dont call for ribs because of the thick fillets you put down and also the seat acts as a support. I did consider adding them anyway for the extra strength though.
