2. This particular craft was one of the first built entirely by Hovermarine Limited, the previous versions being built under subcontract, and after three years use as a passenger ferry by the Norwegian company, Fjordbuss, it was bought back by Hovermarine and sponsored by the DTI for research and development.

3. The bow loop skirt developed using HM.2 no. 17 quickly became standard and was retro-fitted to the earlier models.

4. The rear skirt developed on no. 17 was revolutionary and was the pioneer for all rear skirts used around the world. Prior to no. 17 rear skirts were generally loop and segment skirts but this craft was the first to be fitted with a skirt which was entirely loops. This was a great innovation since, prior to this development the life of a rear skirt was about 500 hours and this design proved reliable for 10,000 hours, or about 5 operational years.

5. Aluminium lift fans were also tested and developed on this craft. Previous models had been fitted with fibreglass lift fans which lasted about 2,000 hours. The new aluminium fans were given a warranty of 10,000 hours but proved much more reliable and have hardly ever failed.

The Importance of the HM.2 Design

Following the initial development of the first hovercraft, SR.N1, the problem of retaining the air- cushion was tackled in a number of different ways. The SR.N1 had no skirt in it's first incarnation and, although it worked, it had a very low hover-height and could not cope well with obstacles. Whilst one avenue of development tackled the flexible-skirt, fully-amphibious idea, a parallel development was going on with the idea of solid sides. The advantage of rigid walls is that the passenger cabin can extend the full width of the craft and the amount of skirt vulnerable to wear and tear is minimised. The craft is no longer amphibious but it has other advantages in that it can operate effectively as a fast passenger ferry and, since it has to remain afloat, it can have water screws and rudders which improve the manoeuvrability.

There were two companies which produced experimental craft prior to HM.2. Denny produced the D.1 which was the first experimental craft and has now been destroyed. They also produced three or four D.2s, one of which has survived in Trinidad and one is now used as a houseboat in South Carolina. A parallel development was going on at Hovercraft Development Limited and HD.1 was fitted with solid side walls and air screws. HD.1 was the forefather of the HM.2 but HD.1 subsequently had the side walls cut off and was fitted with a fully-flexible skirt. Since HD.1 has also been destroyed the HM.2 is the earliest surviving side-wall craft.

Heritage Value

Approach to Conservation

The HM.2 is unlikely to ever fly again although it would be possible to re-fit it. The damaged fibre-glass has been professionally repaired and it has been repainted in order to give a presentable appearance and help to keep out the effect of the weather.

Ideal Standard of Care

This craft is very important in development terms and the last good example of it's type that is likely to be available without the great expense of bringing one back from abroad. Ideally it should be kept in a clean, dry, covered environment, where it can be properly maintained and made available for public inspection.

Present Condition

HM.2 no. 17 is now stored by the kind permission of Vosper Thornycroft UK Limited at their Portchester yard and has been lifted out of the water. The damage to the hull has been professionally repaired and the craft has been externally repainted. Since Vosper are employed in the defence industry the yard is fairly secure but this can make access difficult. Lifting the HM.2 out of the water has greatly improved the long-term conservation of the craft.

Area Required for Adequate Conservation Storage

200 m² (20 m x 10 m)
Internal storage: 32.16 m² (6.7 m x 4.8 m)
Rear door: 1.2 m x 1.9 m

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