Head Protection (continued from page 265) including wind tunnel work; as a result an RNLI designed wrap around visor (see photograph, page 265) was found to offer the best combination of desirable optical properties and protection. NRDC has applied for patents for this visor and also for a separate optical system for obtaining clear vision. The RNLI has a 25 per cent stake in any royalties on both these patents.

3. Production and supply to ILB stations The RNLI visor has been licensed and is now being made by the Psychiatric Rehabilitation Association (PRA), thereby providing them with satisfying work and the RNLI with a reasonably priced article. NRDC and MATSU meanwhile are offering production rights on the optical patent to appropriate manufacturers.

The production visor consists of a shape punched out of a sheet of 1 mm unbreakable clear plastic, with two adjustable position fixing studs at the lower outboard ends, and locating lugs which tuck under the peak. The side profile of the visor presents a downward rearward slope from peak-tip to the nose. This means that the deflected air flow acts in the same direction as gravity to clear most of the water impinging on it. Any droplets remaining are, due to the visor shape, well inside the eye's focal length and one can thus see quite easily through them. Most commercial visors, due to their forward slope in way of the eyes, do not so easily clear droplets since gravity and air flow oppose each other.

The lower edge of the visor is about 10° below horizontal (the eye's normal line of vision in relaxed posture) and this enables the wearer to see with totally unobstructed vision simply by tilting the head up about 10°, or to see through rain, spray and hail, by tilting the head down.

Extending the visor downward to protect the lower part of the face and including slots had also been investigated, but other problems such as the concentration of liquid, turbulent air or misting terminated those lines of development.

To guide NRDC, MATSU and the RNLI in the various stages of progress, a steering committee was set up by Mr K. Grossfield of NRDC which was fortunate in having as members, in addition to representatives of the three organisations concerned, three experts in their own fields: Surgeon Captain J. D. Walters, Institute of Naval Medicine; Mr J. D. Booker, Royal Aircraft Establishment; and Mr P.

Davison, Transport and Road Research Laboratory.

The advice and experience of these men were most welcome, and it is gratifying that both Captain Walters, on behalf of the Navy, and Mr Davison for road users, are still pursuing their own investigations on the helmet/visor combination which the RNLI has selected. One particular bonus brought out by Mr Davison's investigations is that glare caused by wet visors when lights are shone at them can straightway be eliminated simply by tilting the head; conventional visors would need to be retracted or removed.

So, after initial use by the RNLI at sea, perhaps the visor will become popular with motorcyclists. Our manufacturers, PRA, hope to place it on the motorcyle market and since it is designed to fit all sizes of four of the major types of helmet, it is hoped it will suit most others.

While not a first aim of the project, it has always been the RNLI's intention to select a helmet finished in a bright, clear colour. The finish of the original one-size helmet selected some years ago was Dayglo orange, but it has become faded due to exposure to ultra violet light and chipped with age. A number of firms have co-operated in producing fluorescent painted helmet samples, but after six months of use, or even non-use, deficiencies in painted versions have emerged. Gloss finished painted surfaces seem to chip away from the plastic shell easily and matt surfaced coatings pick up dirt, although providing a better night target in a beam of light. The latest British Standard for motorcyling helmets (BS 5361) has highlighted our problem by specifying that 'the shell should have a finish that affords good conspicuity'.

The Institution is currently faced with the option of: (a) re-painting helmets about every two years; (b) awaiting the development of suitable durable bright paints; or (c) turning to self-adhesive fluorescent/reflective panels to be added to the crown of the helmet.

In the short term, a number of painted Dayglo helmets are still being evaluated and as an interim measure, to get the visors in service, white helmets have been purchased and issued. These were found to be more easily seen at dusk and in a beam of light at night at several hundred yards than any other standard colour available. The Dayglofluorescent and retro-reflective finishes were, of course, better in all visual respects, but until they can withstand the rigours of use and abuse for, say, two to three years, they will continue to be experimental only.

The RNLI hopes to offer lightweight, bright and comfortable helmets and visors first to Atlantic 21 and eventually to all ILB crews. The helmet without visor will also be of use for offshore lifeboat crews. In some Waveney class boats they have been found to filter out the noise in the wheelhouse and yet permit the spoken word to be heard.

In the future, with the development of radio equipment capable of working in a very wet environment, the incorporation of earphones and a microphone attached to a lightweight personal radio may be feasible.

To sum up, the basis now exists for head protection from damage, cold, wet and, to a limited extent, fire. The main objective of the project, ease of vision in adverse conditions, has been achieved.

Further, crew now have a better chance of being seen—and there may be still further improvement in this field—and finally there is the possibility of a new mode of communication. All these features have already emerged from an interesting and continuing project..