Page 45 - Theory and Design of Air Cushion Craft

US hovercraft development 29

Fig. 1.28 Bell Halter BH.110 SES in service with the US Coastguard in Florida.

length to beam ratio and thicker sidewalls, such as those on the US Navy test SES
XR-5 and the Soviet passenger SES model Gorkovchanin. The draft of these craft in
off cushion condition is such that the 'wet deck' no longer enters the water to provide
buoyancy. These concepts are more like a slender hulled catamaran when floating.
The Bell Aerospace Corporation united with Halter Marine Inc. to form a new
company named Bell-Halter Corporation, with the intention of developing a new
type of medium speed SES with commercial marine use in mind: the BH-110 (Fig.
1.28). Bell-Halter used the following guidelines when designing the BH.110:
1. Use the sophisticated SES technical knowledge and experience of Bell Aerospace
Corporation;
2. The craft was specified with medium operational speed, low fuel consumption and
seakeeping quality not worse than that on an equivalent planing monohull, high
speed catamaran or high speed displacement ship;
3. Use conventional marine equipment, materials and construction methods, for a sim-
pler and more reliable craft, as well as with good maintainability and low initial cost;
4. Adopt marine diesel power, welded aluminium alloy structure and subcavitating
fixed pitch water propellers;
5. Adopt thickened sidewalls. During off cushion operating mode, the twin hulls pro-
vide a large buoyancy similar to that on a catamaran, up to 100% of craft weight,
and the clear distance between the wetted deck of craft and water surface was sim-
ilar to that on catamaran, improving the manoeuvrability and performance of craft
at low speed.
The prototype BH-110 was launched in 1978, and was later purchased and modified
in 1980 by the US Navy. Subsequently the crew was increased to 14, and the range to
1000 nautical miles after increasing the fuel capacity. The craft was delivered to the
US Coastguard in July 1981 for trials, and proved to be a craft with good seakeeping
quality and simple hull structure.
Some time later, the US Navy extended the craft from 110 ft to 160 ft, and the all
up weight increased from 127t to 205t. The payload of the craft was increased by 62%,