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Fixed or detachable rudder blade?
De Waal offers several options for connecting the rudder blade to the rudder stock. Each method has its own benefits. In rough seas the joint has to cope with tremendous stresses. It helps to know that we build in a high degree of safety and follow preset production procedures.
Will you opt for a fixed blade or a detachable one? Choose between the welded shrink ring module, the traditional flange construction, or our innovative pacific build, developed by the engineers of De Waal.
1. Are you looking for a fixed rudder blade?
The most commonly used type of rudder blade for inland shipping is the fixed blade. It provides a no-nonsense rigid connection between the rudder stock and the rudder blade. What makes it unique is our shrink ring fitting.
1a. Shrink ring module
The rudder stock is inserted deep into the rudder blade, where it meets a hollow tube. At the most heavily stressed point, at the top of the blade, we fit a heavy steel ring. This ring provides an unyielding shrink-fit around the rudder stock. It is welded in place along the outside. This means that no welding needs to be done on the rudder stock itself! This prevents all kinds of material stresses.
Benefits include low cost and absolutely crack-free construction. The right and most popular solution for inland shipping.
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2. Are you looking for a detachable rudder blade?
If so, select our flange option or the pacific type of build. Both designs offer specific properties and advantages; see below.
2a. Flange
Traditionally, the flange option is the most popular solution. The top of the rudder blade is fitted with a thick flange with several holes in it. At the bottom end of the rudder stock, a corresponding circular flange is fitted. High-tension prestressed bolts are then used to clamp the two flanges together and create a solid structure.
Pros: traditional flanges offer a detachable and relatively affordable solution.
Cons: Welding stresses are introduced where the flanges are attached to the blade and stock. In spite of this, it is a popular and durable solution to create a detachable rudder blade.
2b. Pacific type
The Pacific type of build features a rudder stock that passes deep into the rudder blade. Near the centre of the rudder blade the stock is held in place by a tapered seat and secured by our special hydraulic pin. A unique design in ship-building, the solution lacks any visible flanges, making it highly suitable for use in super yacht construction as well as in maritime designs that call for easy disassembly.
Pros: saves time during assembly and disassembly, avoids welding stresses in the rudder stock. The lack of flanges results in optimised flow profiles and avoids gap losses between the rudder blade and the rudder head box. Long-term guarantee against cracks appearing in the rudder stock.
Read the newspaper article about the Pacific rudder