Quote:
Originally Posted by Jeff_H
The rudder on the Allied Princess is what at the time was called a 'Constellation Rudder'. It was developed by S & S through a lot of tank testing and was found to require less drag for any given rotating force. The idea was that more of the blade operated in free flowing water rather than in the highly turbulent layer near the surface. Another factor that came into play is that boats of this era, like the Princess, tended to sail at higher heel angles than boat that preceeded that era, or modern boats for that matter. At these large heel angles more of the rudder is operating near the surface and so ventilation of the blade was more likely to occur when heeled. The Constellation rudder placed more of the rudder blade away from the surface.
Of course at sharp rudder angles, these blades were more prone to producing larger tip vortexes, but on a long keel boat like the Princess the tip vortex of the rudder was fairly minimal part of the overall drag and not worth considering.
Anyway, if you chose to do a more traditionally profiled rudder you would need more surface area than the rudder that you have and so would probably see no gain in speed.
Respectfully,
Jeff
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Good discussion. The Allied Princess rudder looks very similar to what Ron Rawson replaced his original Garden designed rudder with.
My Rudder (1977 and later):
Earlier:
Allied:
