EARLY NOVEMBER saw the first launch from Fairey's yard at East Cowes of the RNLI's prototype fast slipway boat City of London. It was the start of the exact, and exacting, programme of builder's trials through which every lifeboat must pass but which takes on an even greater significance when the boat being tried is the first to be built to an entirely new design.

During this programme the RNLI's technical and operational staff have to satisfy themselves that the new boat meets in every way the high standards demanded by the specification.

The first item in the programme of trials was the checking afloat but at moorings of the vital alignment of the shafts which transmit power from the twin General Motors 8V-71 marine diesels to the FSB's twin propellers. Next, with ballast on board to simulate the weight of any equipment not yet fitted, came a preliminary inclining test to find out the vertical (and fore and aft) position of the boat's centre of gravity and thus get a rough check of her stability (a further inclining test is made later when the boat is fully equipped); also a minimum fuel trial is carried out to establish her true range.

Now came the time, on November 17, for the FSB prototype's righting trial (see right). The boat was 'capsized', being hauled over through 180 degrees by crane until she was fully inverted. When the lines were released, it took the FSB only five seconds to come upright and shake herself free of water, and, as can be seen in the third photograph down, a central strip of the foredeck remained dry throughout. There was scarcely a drop of water to be found below decks and the FSB had come through with flying colours.

For the radar installation the righting trial was also an important test. From the photographs it can be seen that the radar scanner, which had been made watertight, was in position.

The FSB's Decca 150 radar was operating as she was capsized but, as designed, it automatically switched off before the scanner entered the water so that the scanner would not be damaged by revolving in the sea. The system used for watertighting is arranged so that after the boat has righted herself the radar must be switched on again manually before a picture is once again obtained on the display.

After the righting trial, the FSB returned to Fairey's yard and was hauled out so that all her other electronic equipment could be fitted. Then she was once again launched to continue her trials. One day was given over to a short sea trial during which an exhaustive check, item by item, was made of the functioning of each unit in the machinery and in the electrical system. Then came the first of the FSB's extended machinery trials, when on five separate occasions she was at sea for between four and six hours; during the first of these sea trialsher compass was adjusted and during the next her radar and radio were put through their paces.

Other days were given over to trials of each item of deck equipment, to progressive speed trials over the measured mile and to fuel consumption measurements, and also to a final inspection by RNLJ and Lloyds overseers before the prototype fast slipway boat was hauled out for the second time, just a few days before Christmas. Then followed the detailed completion of her fitting out and her final painting in preparation for operational trials early in the new year.

(to be continued).