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RUDDER BLADES AND STOCKS

This is a simple method for accurate construction of a balanced rudder blades.

1. A solid fibreglass plate on the blade centerline determines the planform and a series of glass foil shapes (5 on this rudder) act as accurate guides for forming the foil shape.

The rudder stock or a sleeve to accept the stock is fitted to the central plate before the foil shapes are fitted.

PVC foam blocks are then placed between the foil templates and planed down to the final shape. Finally the trailing edge is trimmed, squared off and reinforced before the final lamination of the blade.

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One of the problems we come up against in installing rudders in cats is that if you permanently fit the stock to the blade in the construction stage you have to either fit the rudder when the boat is lifted by the crane at launch, or dig a deep hole in the workshop floor. I've seen both solutions used in various workshops.

Arnie Duckworth is one of the more creative thinkers when it comes to finding simple build methods and these images show his solution to the rudder and stock installation problem.

A thin carbon sleeve was moulded over the composite rudder stock and fitted to the blade central plate. This allows the stock to be dropped into the hull from above and fitting the blade to the stock by pushing it up from below. 

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Left: Blade faired ready for glassing and showing carbon sleeve to accept rudder stock.

Left: A full size pattern is provided for the Rudder Plate and the foil templates. They are also available as a Dxf file if a CNC is being used to cut the pieces.

Below; Fairing the foam blocks, firstly with an electric plane, and final sanding with a fairing board.

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Left: A full size pattern is provided for the Rudder Plate and the foil templates. They are also available as a Dxf file if a CNC is being used to cut the pieces.

Below; Fairing the foam blocks, firstly with an electric plane, and final sanding with a fairing board.

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Left: Tiller steering system for Raku 44 currently under development.