Harbour defence motor launch
ML 1322, a Royal Australian Navy HDML, in Brisbane in 1944 | |
| Class overview | |
|---|---|
| Name | Harbour defence motor launch |
| Completed | 486 |
| Active | Until the early 1970s |
| General characteristics | |
| Displacement | 54 tons (full load displacement) |
| Length | 72 ft (22 m) |
| Beam | 16 ft (4.9 m) |
| Draught | 5 ft (1.5 m) |
| Installed power | 152 bhp (113 kW) each engine |
| Propulsion | Twin handed Gardner 8L3 marine engines |
| Speed | 12.5 knots (23.2 km/h; 14.4 mph) |
| Range | 2,000 mi (1,700 nmi; 3,200 km) at 10 knots (19 km/h; 12 mph)(1,650 gallons) |
| Complement | 2 officers, 2 petty officers and 8 ratings |
| Armament | Typically twin 20mm Oerlikons, twin Vickers K machine guns and six depth charges |
The harbour defence motor launch (HDML) was a 72 ft (22 m) long British-designed motor vessel used for harbour defence during World War II. Nearly 500 were built by numerous Allied countries during the war.
The HDML was designed by W J Holt at the Admiralty in early 1939. During the war HDMLs were constructed, mainly by yacht builders, in the United Kingdom and a number of other Allied countries. In view of their later expanded combat roles in some Commonwealth navies some HDMLs were re-designated as "seaward defence motor launches" (SDML) or "seaward defence boats" (SDB).