Twin engine
The twin engine is similar to the twin fan, except that each fan has its own engine. The transmission is simpler than the twin fan type, but there are now two engines to maintain.
A 3 seat twin-engine craft from BBV – a quiet & capable cruiser (www.bbvhovercraft.co.uk)
The twin engine design provides independent control of lift, which is useful in some circumstances.
Fans and Propellers
There are two methods of providing thrust, ie a ducted fan, or a propeller. In the UK the ducted fan is very popular, whilst in the USA the propeller is popular.
There is some evidence that the propeller is more efficient and quieter then the ducted fan, but this is a hotly debated subject so I suggest you take advice and then decide for yourself!
Skirt types
There are two main skirt types, ie segmented and bag, but there are many variations and hybrids. both types seem to be successful in cruisers, so it seems to come down to personal choice in the end.
Segment skirts
This type of skirt consists of many individual segments, often 70 or more to make the complete skirt. Usually the segments will be the same around the front and sides of the craft, and different at the rear, although there could be up 5 types around the craft.
A segment skirt
The advantage of the segment skirt is that is that they are stable and damage tolerant - should a segment be damaged, the neighbouring segments expand to fill the space, and in any case it is easy to change a damaged segment in the field.
Should the skirt catch on something, the skirt attachment points are often designed as a weak-point, and fail before the segment tears. Re-fixing is a simple, quick but sometimes muddy job!