How To Keep Things Straight When Nothing Is Straight

I've been worrying about this for awhile, but now I really have to do something about it. Since I don't have the room to build the entire boat at once. I'm building one ama at a time and then the cabin, all separately.  The risk is that if things are not built straight (enough) then perhaps the beams on the cabin will not fit in the beam reliefs in both amas. So keep that in mind and consider the following.

The hull is fairly straight, while not actually straight, if you know what I mean. So now I have an un-straight hull against which to cut straight beam reliefs, and it better be right.

When confronted with sort of thing I usually look for a technological solutions. So I bought a laser right angle projector. The laser angle will be helpful but is only part of the solution.  Here is my plan.

1.  Use the laser to mark out the as-built center line (red marker) where the centerline intersects
     the bulkheads.

2. Cut/build beam reliefs using as built centerline as reference (use laser angle here)

3. Make jig to fit tightly (simultaneously) in both beam reliefs.  The second ama will be built to
    match this jig.

4. Use jig as an inspection aid when building cabin.

I think this should cover my alignment worries. Although you can never really think about alignment too much.

It is doubtful I will get into the boat shed tomorrow. I am helping to chaperone my son's class field trip.  The likelihood of me volunteering for this sort of thing is positively correlated to ease with which I can imagine something going very wrong. So I'm along for the ride as my son's first grade class explores Pike's Market.