FIRE BOAT. The great desirability, not to say necessity for facilities of fighting water front fires from their water side led at first to the placing of fire engines on scows and tow ing them into position. From this primitive makeshift has developed the highly organized modern fire boat with an efficiency surpassing a dozen land engines, to be found in all cities possessing water frontage to be protected.
The first requirement of a fireboat is speedy movement. It must get quickly to the fire. For this its propelling engines must be power ful beyond the ordinary. In addition to power it must be able to manoeuvre swiftly. Its streams of water must be thrown with much greater force than is the case with a land engine, and its pumps must therefore be of great power. To operate this mechanism a very large boiler capacity is necessary. The adjustment of all these requirements has de veloped a fire boat of 120 to 125 feet in length, from 25 to 28 feet molded beam, about 15 feet molded depth and with a draught of from 8 to 9% feet and a displacement of from 450 to 500 tons. The propelling mechanism consists of twin screws of 6 feet diameter and 8 feet pitch, and give a running speed of 14 to 16 miles per hour. To save boiler space and weight the pumps are of the two-stage centrifugal type and operated by turbine engines, which require only half as much steam as recipro cating pumps. In some recently built fire boats (for Chicago) the propellers are driven by electric motors served by generators. These may be controlled direct from the pilot house without calling upon the engineer. The fuel used is generally coal, and steam sufficient to run the boat is kept up night and day. Upon receipt of a summons to a fire the fireroom hatch is closed and the blower started, pro ducing in the fireroom the forced draught neces sary to raise the steam pressure to full working capacity — from 200 to 225 pounds per square inch. In a Seattle fire boat the fuel is oil, sup plied. to four boilers by four burners to each.
When lying idle only 'one or two burners on each boiler are needed to keep up steam and the others can be instantly lighted when an hlarm is received. The water delivery system is oper ated by two sets of pumps which take the water through 14-inch intakes at the level of the bilge of the boat, and pump it into a 12 inch or 14-inch main which encircles the vessel. The pressure exerted upon the main is from 180 pounds per square inch upward for a de livery of 9,000 to 11,000 gallons per minute. The two pumps can be compounded so as to deliver 5,000 gallons per minute at 250 to 300 pounds per square inch. The nozzles are dis tributed about the boat, all being connected with the main. The principal nozzles are the two monitors, one located (usually) on top of the pilot house and a second one aft. They range from 454 to 5Y2 inches diameter. Be sides these there are from 8 to 12 hose con nections for DA to 3/-inch hose. In some of the newer New York fire boats there is a standpipe 27 feet in height placed near the stern of the boat. This has at its top a deck orplatform from which the firemen are able to fight a fire in the second story of a pier with much greater efficiency than from the water level. Fire boats carry usually up to 1,500 feet of hose, of size for interior work and 3/-inch for outside work. These hose lines may be extended inshore as far as 500 feet and do effective service. The New York fire boats have also connections by which they can couple to the pipes of the high-pressure service at the water's edge, and by their power ful pumps aid in fighting fires which are far inland. Consult West, C. C., 'Centrifugal Pump Fire Boats) (in Transactions of the So ciety of Naval Architects and Marine Engineers, Vol. 16, pp. 211-228).