Old boat, old manual. The Chesapeake series dates from the previous century when leaving in the stitches and burying them in fat fillets was considered the done thing for all S&G boats. Since then, people have discovered all the advantages of pulling the stitches and the builder community has shown itself willing and able to take the extra time and do the work of pulling to get these advantages. But the manuals were never updated for this.

So yes, by all means pull them. I've built a CH16LT and a WR18, both from that era, neither with the stitches left in and never missed them. I also didn't used thr ring nails to attact the decks, just glued them on.

Have fun,

Laszlo

PS - fortunately, the laws of hydrodynamics have not changed in the last 2 or 3 decades, so the Chesapeakes hull shapes still perform every bit as well as they did back when they were originally designed.

   I'd remove the stitches.  If you just cut off the exposed wires the cut pieces get snagged on the sand paper, it makes the fillets thicker to cover, and I cut some fingers when checking smoothness. 

Stitch & Glue has come a long way since the first kits were sold & built. It's really easy to pull stitches as long as you use some means to apply a bit of localized heat to break the epoxy bond that otherwise would make pulling stitches pretty tedious.

Soldering guns are a popular tool for this purpose, it takes seconds to get a stitch up to temperature high enough to release from the epoxy.

A quick tug with a needlenose pliers is all it takes to pull 99.99% of 'em free. The .01% are safe enough left behind.   

On our PMD build, we used one of those long necked butane lighters to good effect.  Cut the copper on one side of the knot with nippers, apply heat to the knot while pulling it away from the boat with pliers to help keep the flame away from the boat, and the wire will slip right on out when it's ready.  Easy peasy.

.....Michael

   Huh, didn't know this when i built my C16LT last year.  Just followed the directiions and left the stitches in.  Seems to have worked fine.  I did use a file to knock down the copper on the outside, but wasn't too much work.