Join Date: Jul 2008
Location: SW Florida
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Re: Spade rudders vs blue water passage making
Solid shafting will not merit anything as essentially all or most of the bending stress is carried in the first few % of depth along the surface of the material. Crevice corrosion AND bending stresses which promote fatigue (cracks) because the endurance limit was exceeded .... once it penetrates into the macrostructure will cut even 'solid' metal like a knife through butter; same as how a puny little girl could rip apart an old fashioned thick phone book. When it comes to 'cantilevers' you want 'good' not 'solid'.
The reason pintle/hinge hung rudders are preferred for 'blue water' is they are less subject to bending stress because of their inherent (hinge) 'support'. Cantilevers are always 'bending'.
good thread guys...I have been postponing my rudder repair alot...I guess because I probably need to haul out...I never liked spade rudders and have never owned a boat with one...after reading this discussion and realizing the forces at work I will probably never own one...for the type of sailing I like to do...but if I was a racer or stayed solely in the bay I would certainly not rule them out.