Part of my keelson was replaced at some point in the past. The ribs just butt up to the keeson without any conection. What would you recommend as a way of attachment between the keelson and ribs?
Add to the width of the keelson with a proper piece of all-heartwood white oak. Screw the ribs from the bottom of the boat into this new piece of wood. You will have to screw thru the plywood hull planking thru the rib and into the new wood.
what Lancerboy said.... But a word of caution, be sure that the new ribs have sufficent thickness to completely fill the gap between the new keelson sisters and the plywood garboard plank. If not the new screw will crush the plywood and/or not seat the rib firmly to the sister.
Joe B