New High Aspect Ratio Rudders Now Available
Updated August 15th, 2009
Special high performance carbon fiber rudder systems have now been developed for both the F-22 and F-32 by Farrier Marine, and are now readily available. Daggerboard rudders were first used on Farrier designs back in 2004 with the original F-33, and this worked very well, to where all new designs since have used only a daggerboard rudder.
The same 'kick back' style rudder was also used for the F-32, and plans are available to build your own
It was then decided to offer a 'ready to go' daggerboard rudder system after seeing too many production and after market 'high performance' rudders break, from either inadequate design or poor construction. Most do not realize how large the rudder loads can be on a high speed multihull, and it is essential for such rudders to be both designed and built correctly.
These premium all composite rudder systems use a new high aspect foil section that is very resistant to ventilation, and has a quicker helm response. The F-22 rudder can also be used on the F-24, F-25, and F-82, while the F-32 rudder can also be used on the F-9, F-31, F-33, and even as a maxi super rudder for the F-28. Either rudder can also be used on similar size catamarans or monohulls.
The daggerboard rudder configuration was chosen due to two key advantages, these being the ability to maintain good control in shallow water, plus the blade can also be lifted in light airs for less drag.
The alternative kick-up style rudders, where rudder blade is pivoted in the case to allow swing back, have been used successfully for years. But, they come with one very annoying problem - they are just about impossible to steer with when swung back to reduce draft for shallow water. Daggerboard rudders easily solve this problem by lifting vertically, to maintain excellent control, and without a huge tiller load. They have also been around for years, but also come with a problem - they usually cannot kick back. Thus if one hits anything the rudder can be destroyed, or worse, ripped off the transom.
The prototype F-32 blade was made in 2007 for Pete Pattulo's F-33R, who wanted a deeper and more performance orientated blade. Pete's original F-33 rudder case sleeve was modified at Farrier Marine in New Zealand to suit the new blade, and then air freighted back to Pete in time for the 2007 Miami-Key Largo Race. Pete reported back:
The rudder is working great!! It was like going from a car with really bad/sloppy power steering to a sports car with precision steering. We've now had up all the fore sails and the helm is perfect and balanced in all configurations. We were first to finish on the Miami to Key Largo race!
Thanks again! - Pete
In the past, ready made production rudders were always a problem, as they are hard to make, and frequently the final shape left much to be desired, with the join seam only 'so so'. Blades were also frequently thicker than they should be, or were warped, or halves were misaligned, while the metal cases were heavy, and prone to both corrosion and fatigue. The result was always something that would do, rather than something to be proud of.
However a number of new manufacturing processes have now been developed at Farrier Marine and the blades and cases are easily the best I have ever made or seen.
The rudder blade molds have been CNC machined for the perfect profile, and are substantial, in order to maintain the correct shape without any twisting. The rudder halves are also aligned perfectly with six stainless steel alignment pins in special bushes embedded in the mold and placed accurately during CNC machining.
Production rudders are normally made in two halves and then joined together from the outside, but alignment and finished thickness has always been hard to control, as was straightness. However these new rudders are being joined from the inside, while being resin infused in one piece. The assembled molds are being held straight, at the correct thickness, and in perfect alignment. The final shape is thus virtually seamless, straight, or as near perfect as one can get.
The case has also been further developed, due to the fit of the blade in the case being so important for 'feel' and ease of use. Too tight and one cannot raise or lower blade easily, too loose and the helm will be spongy due to movement of the blade in the case. Cases are commonly made to a fixed size, and then lined with a marine carpet, but if fit is not exactly right, or carpet too thick, it will never work well. Making the exact size has always been difficult, and thus a fully adjustable 'double molded' case has been developed, with a very thin synthetic fabric being used as a liner.
Width is adjusted by adding or subtracting shims each side of a plastic aft end strip (the case comes pre fitted with shims each side), with cross bolts being insulated from carbon case by special stainless steel collars embedded in epoxy resin. Fore and aft length can be adjusted by simply adjusting two (F-22) or three (F-32) nyloc nuts on aft case edge, which will move the end strip forward or aft. It can also be angled slightly if need be to adjust balance area. Rudder blade fit can then be perfectly optimized, while the plastic strip is gentle on the rudder trailing edge.
The F-22 Rudder blade and case
Both F-22 and F-32 rudders are of premium quality, have been designed for low weight and high performance, while pricing is very competitive due to the highly efficient manufacturing processes that have now been developed.