Starting engine out of water
Get a 5 gallon bucket, a supply hose that has at least 3 gallons per minute water flow. Disconnect the inlet water hose from the seacock and place it in the bucket - start the engine and keep the water level of the bucket so that the inlet hose is completely submerged. ... otherwise you risk breaking the water pump impellers and burning the fiberglass water lift muffler when running dry - even for short periods.
Dont just simply attach a hose to the water inlet hose but use the bucket so that you are SURE that the cooling circuit is full.