Fitting shims between the iako (crossbeam) and the top of the gunwale allows
you to change the attitude of the ama. If you use the aft seat with no other
crew on board, you may notice the stern of the ama dragging. A shim at point "A"
will lift the stern of the ama. A shim at point "B" will lower it. A shim at "C"
will lift the bow of the ama and one at "D" will lower the bow. Experiment
with these settings to get the best from your canoe.