[Ichthypresbyter]

Rowing alignment is slightly different from swimming alignment.

In swimming, the start and finish are both fixed physical objects that the swimmer must touch (though in all events except backstroke, the start is a bit weird because it's outside the pool).

In rowing, the finish line is an imaginary line much like cycling or running. While at the Olympics there are 'clogs' to hold the bows of the boats which drop down at the start:

https://www.polaritas.com/products-and-services/automatic-st...

a race official is always required to certify that the bows are aligned, which is why the gates are transparent (and the system includes video cameras to help this official).