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* Ballasted Lifting keels are heavy - and therefore require a a great deal of time and effort to raise * Because ballast lift keels are heavy, they require a complex mechanism to operate, such as a worm gear, wire rope and drum winches or even electric winches - all of which require considerable maintainance and can be prone to failure. * Ballasted lift keels only offer stability when a mechanism is used to lock them down in place. If not locked a lift keel can slide back into the hull during a roll and actually contribute to a capsize. * When locked down a ballasted lift keel can not safely "kick up" should shallows be encountered. * The advantage of ballasted lift keels is that the ballast is low down affording the yacht with good stabiity. |
Viva Yachts are different.... |
Viva yachts have the majority of their ballast (steel pressings) encapsualted permanently under the cabin floor rather than in the swinging centre plate, which means the following advantages.. * The centre plate is relatively light - meaning it requires very little effort and time to lift. * Because it is relatively light the centre plate requires only a simple rope and pulley mechanism to operate form the cockpit, which is very low maintainance and extremely reliable * Because the ballast is permanently under the floor rather than in the centre-plate, the yacht is stable whether the plate is up or down * The centre plate does not need to be locked down and therefore is free to pivot upwards should the centreplate touch the bottom * Because the encapsulated ballast in a Viva is located higher uo than a lift keel's would be, extra ballast is incorporated to ensure high stability...around 25% more than the equivalent sized lift keel yacht. This high ballast ratio (the ballast is around 35% of the total yacht's weight) contributes to the Viva's superb stability - the Angle Of Vanishing Stability (AVS) for the Viva 700 is 150 degrees...which is very comforting to know when the going gets rough. Drying Out When the swing centre plate is fully retracted, Viva yachts sit upright on the ground, and the encapsualted ballast, as opposed to the hollow fibreglass bottom of a ballasted lift keel yacht, provides an extremely strong and solid base upon which they sit. Take a look at this link to see a graphical representation of a swing centre plate. It is from the larger Huzar 30, but the system for the Viva Yachts is extremely similar. Click here. |
Some thoughts about lifting keels... |