Design_and_description Brazilian_monitor_Alagoas

1 design , description

1.1 propulsion
1.2 armament
1.3 armor

design , description

the pará-class monitors designed meet need of brazilian navy small, shallow-draft armored ships capable of withstanding heavy fire. monitor configuration chosen turreted design did not have same problems engaging enemy ships , fortifications did casemate ironclads in brazilian service. oblong gun turret sat on circular platform had central pivot. rotated 4 men via system of gears; 2.25 minutes required full 360° rotation. bronze ram fitted these ships well. hull sheathed muntz metal reduce biofouling.

the ships measured 39 meters (127 ft 11 in) long overall, beam of 8.54 meters (28 ft 0 in). had draft between of 1.51–1.54 meters (4 ft 11 in–5 ft 1 in) , displaced 500 metric tons (490 long tons). 0.3 meters (1 ft 0 in) of freeboard had towed between rio de janeiro , area of operations. crew numbered 43 officers , men.

propulsion

the pará-class ships had 2 direct-acting steam engines, each driving single 1.3-meter (4 ft 3 in) propeller. engines powered 2 tubular boilers @ working pressure of 59 psi (407 kpa; 4 kgf/cm). engines produced total of 180 indicated horsepower (130 kw) gave monitors maximum speed of 8 knots (15 km/h; 9.2 mph) in calm waters. ships carried enough coal 1 day s steaming.

armament

paraguayan canoes approaching alagoas, in vicinity of timbo batteries.

alagoas carried single 70-pounder whitworth rifled muzzle loader (rml) in gun turret. 70-pounder gun had maximum elevation of 15°. had maximum range of 5,540 meters (6,060 yd). 70-pounder gun weighed 8,582 pounds (3,892.7 kg) , fired 5.5-inch (140 mm) shell weighed 81 pounds (36.7 kg). unusually gun s brazilian-designed iron carriage designed pivot vertically @ muzzle; done minimize size of gunport through splinters , shells enter.

armor

the hull of pará-class ships made 3 layers of wood alternated in orientation. 457 millimeters (18.0 in) thick , capped 102-millimeter (4 in) layer of peroba hardwood. ships had complete wrought iron waterline belt, 0.91 meters (3.0 ft) high. had maximum thickness of 102 millimeters amidships, decreasing 76 millimeters (3 in) , 51 millimeters (2 in) @ ship s ends. curved deck armored 12.7 millimeters (0.5 in) of wrought iron.

the gun turret shaped rectangle rounded corners. built hull, front of turret protected 152 millimeters (6 in) of armor, sides 102 millimeters , rear 76 millimeters. roof , exposed portions of platform rested upon protected 12.7 millimeters of armor. armored pilothouse positioned ahead of turret.