Page 47 - Theory and Design of Air Cushion Craft

US hovercraft development 31

SES mine countermeasure craft (SES MCM)

The development of these craft, shown in an artist's impression in Fig 1.29, was devel-
oped as follows:

Initial design phase (December 1982-November 1984)
Since the shock vibration of hull structure due to underwater mine explosions could
be reduced by 60-80% compared with that on conventional craft, it was expected that
hull structure weight could be reduced considerably. Additionally the underwater
hydrodynamic pressure signature and acoustic field due to the motion of these ships
were expected to be decreased dramatically because of the existence of the air cush-
ion. SES were therefore projected to be very suitable for MCM because of these
advantages. Meanwhile, the craft could provide a larger deck area than that on con-
ventional ships and a more stable platform for continuing work on mine sweeping
operations in rough seas. For this reason the US Navy began to develop the MCM
SES in December 1982.

Detail design and construction
The US Navy signed a contract with Bell Halter Corporation at the end of 1984 to
build an SES MCM entitled the 'Cardinal' class, with a length of 57.6m, width of
11.9m and draught of 3.68m in off-cushion condition, 2.41m on-cushion. The cushion
pressure was 7000 Pa and light/full displacement of craft were 359/452 t, respectively.

Fig. 1.29 Artist's impression of US Navy MCMH SES.