EXCELLENCE IN DESIGN AND ENGINEERING
“The boat did not feel tender relative to the standard 82 even when pressed to rail down.”
The centreboard design Once all these factors were carefully evaluated, it became obvious which system was right for Oyster. With two customers waiting in the wings for centreboard 82s and the performance indicators more than promising, the green light was given to start engineering the system. A significant list of critical requirements were immediately laid down in terms of safety and as near as could be achieved maintenance-free operation:
• A precision-engineered pivot bearing must be designed to completely avoid any possibility of the annoying ‘click-clack’ noise of the board when the yacht rolls. Quite often an annoying trait of centreboarders. • Twin rudders to be provided to keep rudder draft down while maintaining excellent steering and tracking characteristics and as with all Oysters, the rudder draft to be less than board-up keel draft to afford the rudders protection from the fixed lead keel.
• The Oyster centreboarders should, as with the mainstream Oyster fleet, surpass the stability criteria for unlimited ocean voyaging.
• Rudder tips to be kept inside the line of the hull to avoid damage from a dock.
• Underwater components should be all bronze to virtually eliminate corrosion.
• The lift system was to be powerful enough to lift the board with the yacht hard on the wind in normal circumstances.
• No lift ram should be in the water to avoid maintenance and corrosion problems and negate the potential for oil leaks and pollution.
Confirmation on performance came when the 82 centreboarder was first commissioned at Oyster. On a brisk day, blowing a steady 20 kts from the southeast, several members of the design and commissioning team took her on sea trials with a freshly calibrated log. The numbers were carefully recorded. Back at the design office we compared the figures to the VPP and tank test results produced several months earlier. The performance stood up to and at some points surpassed expectation. The boat did not feel tender relative to the standard 82 even when pressed to rail down. To add to our satisfaction, she was found to be very light on the helm when well pressed, with the lee rudder being in its most efficient vertical position it gave great balance and feeling of control – a point well appreciated by the twin rudder Volvo 70 crews in the southern ocean.
• We must design a functional capability to free a jammed board should the need arise. • Board up/down interlocking fail-safe system must be 100% reliable to avoid damage in the event of lift system failure or jammed board. • There should be enough strength in the board to withstand pushing the boat to full heel should the board tip take the ground while being driven stern first onto a lee shore on a dragging anchor. The board is solid bronze. • An emergency back-up lift system using a normal sheet winch at loads no greater than the headsail sheet should be provided.
With the outstanding success of the first two centreboarders we have extended the idea across the range without changing concept or design essentials and the first Oyster 655 centreboard started building as we went to press. >
• It must be possible to replace the lift line with the boat afloat, to avoid slipping problems in more remote cruising locations.
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