Examples of repairs : re-design new rudder

Example 1
Design and manufacture new rudder on 12 ton Hillyard.  The original rudder on this class is the semi elliptical broad rudder that is relatively inefficient because of its limited area deep down and occasionally very heavy because of its considerable leverage at mid  height. 

A new rudder was designed to have much more efficient area in lower deeper denser water without the overall considerable leverage of a very wide rudder. 

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Perhaps liken this to a sailing dinghy with a pivoting rudder, there is enough force on the rudder when it is lifted to break the tiller but, when the same rudder is dropped into deep water the vessel becomes responsive and considerably lighter on the helm. 

This rudder is constructed from iroko boards jointed widthwise with 13mm blind Bronze rods (dumps) inserted to prevent it distortion.
Overall the improvement on general handling is greatly improved with much lower rudder forces and more response.

Points to remember when designing rudders :

• Adequate clearance to allow for taking the ground. Bottom edge should be cut-up so rudder can move freely when aground.
• Fair off the leading edge to improve water flow from prop.
• You must not rely on glue alone - dumps must be fitted to take strain otherwise rudder could split under severe conditions eg weather-helm.
• The rudder should be  a close fit to the keel so ropes cannot get jammed in the rudder-shut.
• Adequate clearance for hull and prop