Some people are nervous about running engines while ashore, but the fact is while the boat is out on the hard it's a great time to flush things through with fresh water, especially with a direct seawater cooled engine.
This pic was sent by my friend Greg taken at Netley Cliff SC, it's a 5 gallon (that's 25 liters for those on the metric system) container tied to the transom, into which the exhaust is routed using a temporary extension. The through hull log has been removed so that the water hose is routed inside the boat and connected to the water cooling pump.
The engine chugs away circulating the cooling water, very neat.