Why a US carrier shooter touches the deck

Why does a US carrier shooter touch the deck before signaling an aircraft to launch?

The strongest explanation is that it visibly confirms the deck is clear before the launch signal, though traditions about luck or grounding are also reported.

Three explanations are presented because the evidence does not support certainty. The gesture may be traditional luck, a way for the shooter to ground and check himself, or a visible statement that the deck is clear. The last explanation best connects the touch directly to the following point toward the bow. Redundant visual signals support safety amid jet noise and deck activity.