Centreboard

The main role of the board is to provide lift when sailing close-hauled and reduce leeway when reaching. With the board fully down the boat draws eight feet and, if sailed properly, will point almost as high as most cruising boats. Sailed properly means that when hard on the wind sail trim is critical, a good speed must be kept up and heeling too much must be avoided or she makes a lot of leeway. There is a certain technique in sailing a centreboarder efficiently, not just on the wind but off the wind as well. This is when the centreboard becomes a true asset as it allows one to reduce the wetted surface. Also, the ability to lift the board gradually as the apparent wind goes past 135° up to the point when the board is fully retracted is a great advantage as the risk of broaching is virtually eliminated. The absence of a keel to act as a pivot in a potential broaching situation means that the boat does not tend to round up when, in a similar situation, a keeled boat would do just that. It is a feature that I have blessed on many occasions and has allowed me to continue keeping the spinnaker up longer than I would have done otherwise. The board is also normally retracted when motoring in calm waters as the reduction in wetted surface provides an extra quarter to half knot of speed.

The main reason for choosing a centreboarder is primarily to increase one’s cruising options and having a boat whose draft can be reduced instantly can be a great advantage.

The fact that the OVNIs have a completely flat bottom means that with the board fully up the boat can dry out on any beach, tidal bay or estuary. When the tide runs out, the boat settles down comfortably, and, as the height of the stern platform is less than two feet above the dried out surface, access aboard is very easy with the aid of the swimming ladder. We have dried out on many occasions, whether to put on a quick coat of antifouling between tides while cruising the Chilean canals or to access a shallow bay in Alaska so we could watch a grizzly bear fishing for salmon.

One other advantage of having a centreboard, which is a solid aluminium plate, is that one can use it as a sounding board when entering an unfamiliar shallow anchorage. With the board fully down and the control lever on the hydraulic pump in the open position, I motor slowly into the anchorage keeping an eye on the depth sounder. If we happen to touch the bottom, there is time to stop and pump up the board. Life has become even easier since acquiring a forward looking sonar (FLS) that shows any obstructions up to about sixty metres (200 feet) ahead allowing the person at the helm to take the necessary avoiding action. But even with the FLS I continue to use the well-tried method of sounding with the board.

The centreboard and rudder are both raised by the same hydraulic pump located in the port cockpit locker right next to the steering position, so it can be accessed instantaneously. The control levers for both rudder and board are normally in the closed position that locks the hydraulic system. On collision with an obstruction, the back-pressure in the hydraulic system blows a sacrificial valve and the board or rudder are free to swing up. The sacrificial valves are thin copper disks that can be quickly replaced. In nine years of sailing I have only blown the system on about ten occasions, usually when entering an anchorage that was shallower than anticipated and we hit the bottom. Try and do that with a keeled boat!