You are correct, and the keel should go tight in the berth. Remember, the keel is the most important element of the ship. It has to stay 90 degrees against the bottom of the berth, firm, and stable without any movements when you will glue the frames. Looking close to your photos, I see the laser char on the keel parts. It is suggested to use a 'plastic wrap' to avoid those marks, also I suggest lightly remove the char from all of the berth parts, specifically for the notches of frames holders (top and middle supports). Frankly, the top notches must be enlarged to accept 4.00 ~ 4.1mm frame width. *NOTE! do not make them too wide, they will be served as a clamp when gluing the frames to the keel.I have placed the keel in the jig and it was a REALLY tight fit. Has anyone else had difficulty getting the keel in place? i was surprised since the keel parts are precisely cut and they only fit together one way. Perhaps I did not put the jig together as accurately as I should have or the cardboard (MDF ?) material does not allow for the same stability as plywood?
I had to enlarge a few of the slots in the jig and at least one small piece of the jig broke off. I found that if a piece of the soft jig material does break it is very difficult to glue back together. You need to reinforce the break with wood or it will never hold.
The part was accidentally broke, very important for the Transom parts assembly. Don't lose it.