Description of the KeelThe following photographs are of the first keel of this type which is being fitted to a 25ft sailing boat designed by Stuart Roy of Yacht & Powercraft Design Services Ltd.
This is a plywood full scale model. The keel plates will be used as patterns for casting in iron.
The keel box is 8ft long and 13ins deep. The plates have a maximum thickness of 2ins and the bulb a maximum thickness of 6ins. The keel extends by 37ins and has a chord of 25.5ins.
This shows the extended keel and the box it retracts into.
In this situation with the keel touching the ground (weight on) the keel is locked in position.
The keel box is now on stands and the keel is weight off. Pulling on the retraction strap initially moves the top of Plate 2 rearwards. This movement allows the top of Plate 2 to clear the down lock stop which it engages with when the keel is ‘weight on’.
This shows the keel partially retracted.
For this boat the strap enters the keel box at the rear.
The strap then passes over a roller at point X, over the top of Plate 2 and then down a slot in the joint between the two plates and is attached to the Hinged Link.
The keel bulb houses the Hinged Link.
The Hinged Link is now visible, the strap connected to it and the slot in the front edge of Plate 2.
The front plate, Plate 1, is hinged on a substantial shaft and is similar in most respects to a swing keel.
The rear plate, Plate 2, is connected to Plate 1 by the Hinged Link at the bottom and at the top is supported on a cross shaft with a pair of 2ins wheels. The wheels run on guide rails which are on the inner faces of the keel box.
The keel fully retracted.
Advantages of this keel design:-
• No requirement for a keel box in the cabin. Useful space in a small boat is at a premium. My retracting keel is housed in a shallow box under the cabin floor.
• When extended the keel locks in place and becomes effectively a fixed keel capable of taking the full weight of the boat.
• A locked keel will stay in place providing a righting moment in the event of a knockdown or rollover.
• A low centre of gravity for the boat when the keel is retracted.
• The centre of gravity moves aft when the keel is retracted which is beneficial when sailing downwind
• Removing the need for a keel box in the cabin improves the structural integrity of the hull.
• The down lock is as a result of the geometry of the design and is achieved without any additional moving parts.
• There is no risk of structural damage from an unrestrained keel in the event of a knockdown or rollover.
• The keel assembly is housed in a box that can be fitted to the hull in a way that allows for easy removal of the unit should it require maintenance.
• The keel is retracted using a single cable attached to a winch (electric or manual). The keel extends under its own weight.
Patent applied for. Application number GB0809023.5
Licences for the Steynor Keel are available to boat builders and designers, please contact the company.