I've applied a filet of adhesive along the foot of the keel, for one reason because the cut edge of the plywood may leave gaps here. Incidentally if there is an excess of buoyancy in the keel, this is broadly how it will appear at rest in water.
Practically this is no great shakes and has its advantages, so that for instance it can sit in the shallows pending action. A problem though is that it then requires an input of rudder during take-off onto the plane: easy for digital flight controllers but less so for you and me.
