A new larger Hydrovane rudder is priced at EUR 456. They explain why they use nylon for the rudder: it bends when hit by an object or touching the ground, thus saving the expensive shaft.
Here's a copy of the rudder description on the Hydrovane site (NB I have no interest whatsoever in Hydrovane - wish I had).
TWO RUDDERSTWO RUDDERS - The combined effect of two rudders working together is perhaps the most significant advantage of a separate auxiliary rudder system. For downwind sailing in particular, the main rudder can provide the greatest yaw resistance only if it is fixed. To this natural stability the nimble HYDROVANE rudder is tempered to the conditions resulting in yet further yaw damping - which means a more comfortable ride, a straighter course and less potential to lose control in bad seas and risk: broaches, crash gibes and knock-downs.
NEARLY INDESTRUCTIBLE - The rudder is manufactured in solid cast nylon – perhaps the largest single piece of nylon that one may see in a lifetime. With over 20 years of history these rudders have proven to be nearly indestructible. We have yet to see one of our rudders damaged from hitting a submerged obstacle. We believe that on such impact the rudder flexes, bends to absorb the blow then merely fends off the intruder - often unbekownst to watchkeepers and leaving little trace - maybe a scratch but never a gouge - the nylon is so tough ... and flexible.
Avoids Snagging Commercial Fishing Gear - Neither do we hear of the rudder being fouled by commercial fish nets or lines - because:
* Tapered shape - helps line slip off
* Flexibility - rudder bends under load helping such gear to slip free
* Not very vulnerable with hull and keel in front acting as protective barrier
Easy Removal - The rudder is designed for easy removal with a quick release pin that is easily ‘popped out’ with a boat hook. A tether must be kept on the rudder at all times.
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RUDDERS - all solid poured/cast nylon
1. Original (short - 950 mm./37.5") - 1980 to 2005 - 8 kg. (17.6 lbs.)
2. First longer version - 1105 mm./43.5" - 2006 to 2009 - 8.5 kg. (18.7 lbs.)
3. Latest July 2009 onward - 10.5 kg. (23.1 lbs.) - 25% heavier ... maybe 50% more power
OUR RUDDER – For nearly 30 years the rudder has been made of solid nylon poured into a mould. Other than a few manufacturer’s defects the rudder has proven to be unbreakable – an enormous virtue. Over the years various improvements have been made – lately getting larger and thicker. Customers/owners are typically so happy with their rudders - having little interest in upgrading to the newer and larger versions. In 2006 the length was increased by 5.5 inches/14 cm. In June 2009 it got thicker by adding 5 lbs./2.3 kgs. – now weighs 23 lbs./10.5 kgs. The improvements are designed for bigger and faster boats producing more power with less force required to control it. For smaller boats and big high speed boats we shorten the rudders - not needing the extra power or optimizing performance.
The latest version has been named the ‘TH’ – a tribute to our ‘in house engineer’, Ted Hargreaves. Ted inspired the upgrade based on his aeronautical experience with foils. After the first test Ted reported that it is 'scary' as it was so much more powerful but so light to the touch - easy to control - couldn't believe that it could be that good without stability issues. Now we know that it is not 'scary' at all - but very stable. It is a vast improvement. We strongly recommend the upgrade for any owners with older versions of the rudder who would like the extra power.