I asked dwforum folks about repairing this delamination. Wood dowels and bolts were suggested. I thought dowels would look better but wound up using bolts for the ease of installation and strength.
So, I started by using my Fein to widen the crack in order to get fresh wood surface for the epoxy and to make it easier for the epoxy to get into the crack. Then I mixed up a small amount of epoxy and put it in the crack unthickened. I poked at it with toothpicks to get the bubbles to burst and work it the full depth of the crack. I left that to soak in for a while. Then I added some wood flour to the remaining epoxy until it was thicker but still quite runny. I poured that in and worked it the same way with toothpicks. I used a couple of clamps to squeeze it a bit and then left it overnight.
The next day I drilled small pilot holes. Then I used a Forstner bit to make recesses on the inside of the boat. When that was done I drilled 5/16″ holes for the bolts.
After scraping and sanding I varnished the gunwale with about 3 coats. I used a Q-tip to get varnish inside the bolt holes. When that had all dried I bolted it with stainless bolts, washers and locking nuts.