47-foot Motor Lifeboat

The 47-foot MLB is the standard lifeboat of the United States Coast Guard (USCG). The 47′ MLB is the successor to the 44′ MLB.

The 47' MLB is designed to weather hurricane force winds and heavy seas, capable of surviving winds up to 60 knots (110 km/h), breaking surf up to 6 m and impacts up to three G's. If the boat should capsize, it self-rights in less than ten seconds with all equipment fully functional.

The boat's hull and superstructure are constructed entirely from 5456 marine grade aluminum. Designed with a hard chined deep "V" planing hull, the 47' MLB exceeds its displacement speed. The frame is composed of 17 vertical bulkhead frames, each of which is welded to the deck and hull, and five of which are watertight.

Employing fly-by-wire control systems, the boat can be operated from four different locations: two from the enclosed bridge, and two amidships from an open bridge.

Situated less than 1 ft (30 cm) from the water line are recessed retrieval wells, allowing for easier recovery of persons and jetsam, and easier boardings. A watertight survivor's compartment is equipped for comprehensive first aid. It is situated at the combined center of rotation of the ship.

Name: 47' MLB
Builders: Textron Marine
Operators:  United States Coast Guard
Cost: $1,214,300
In service: 1997–Present
Planned: 227, approx
Completed: 227
Active: 227
General characteristics
Displacement: 18 t (20 short tons)
Length: 14.6 m (47 ft 11 in)
Beam: 4.27 m (14 ft 0 in)
Draught: 1.37 m (4 ft 6 in)
Propulsion: 2 × Detroit Diesel 6V92TA DDEC-IV engines, 435 hp (324 kW) each
1,500 liter (373 usable imperial gallons) fuel capacity 
Speed: 25 knots (29 mph; 46 km/h) maximum
22 knots (25 mph; 41 km/h) cruising
Range: 200 nmi (370 km) cruising
Complement: 34 Persons, 4 crew, 30 passengers
Armament: 1 × M240B machine gun (optional)


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