Checking for blocked intake

The troubleshooting steps below seem like they'd work, but "slowly open seacock" means we're looking to (briefly) let water flow into the bilge? "Raw Water Cooling System. Obstructed intake. Plastic bags or other materials can be aspirated into the seacock. Close the raw water intake seacock, remove its water hose, and then slowly open the seacock. If water does not flow, remove the obstruction, replace the hose, and start the engine. If water exits through the exhaust port, the problem is solved."