A builder tip: when installing the lower gutter it is important to NOT cause any movement in the rearmost portion of the #2 panels. This would cause the hatch to fit poorly. I suggest setting a bevel guage for 29 degrees and using wooden wedges and the spring clamps (I don’t know how anybody’s eyesight is good enough to just guess this or how springclamps alone would hold it at nearly the correct angle) to hold the transom portion at 29 degrees while fooling with the sides. With the transom portion fixed (clamped) you will have to push forward and down on the quarter panel gutter section until the forward end (perhaps minus the 1/4″ mentioned in the hymnal) contacts the upper gutter. It needs to be tortured a little bit in the corners over the quarter panels. And in this portion you will not be able to get an angle of 29 degrees. I had to fix my corners in place by drilling holes with a 1/16″ drill bit and hammering in temporary finishing nails (removed later with visegrips after fillets cured). At this point the upper sections of the lower gutter will be bowed downwards and not in contact with the #2 panels. Spring Clamp the upper and lower gutters together where they meet. Then wedge up the bowed side of the lower gutter (with a stick from the galley flat) until it is straight at which point it should just contact but not move the #2 panel. A pencil line drawn in advance with a straight edge on the inside of panel #2 helps immensely. Then fillet the upper side of this portion first.