Rudder hanse 312

RUD 34 rudder from Jefa. No vibrations or humming when clean, but turbulence from the prop when motoring is still there of course. A bit more balanced then the original one, but you can not let the tiller go, even for a moment when motoring. I have made a quick release/adjustable tiller lock for this purpose.

Thanks for sharing your knowledge. I was aware of some historic rudder problems. And I banged on about poor design when I first bought my 301, it had seized rudder bearings problems.

As an excuse I am an old Git;  [virus jab tomorrow]  with far too much history of  boat/boatbuilding/ boat designer issues. I have put to sea in boats that I  have designed and built the Keel, mast and rudders for and had no problem; I have put to sea in boats from respected manufacturers and designers and had problems, due  to either design and/or manufacture.

Just to try and justify my old Git status, when I first had problems with the H301  60mm aluminium rudder stock I offered my solution was to use Duplex Stainless tube, its high strength and total lack of corrosion problems weldability etc mean it can be as light as aluminium by way of  smaller diameter and tubular. The smaller diameter makes plain bearing an option, because needle roller type bearings dont like crustation invasions.

I see Jefra "racing rudders" now offered with Duplex and the thinner section makes for a thinner rudder? Thats progress,  or learning on the job? Some of the vibration just might be due to the thick NACA sections [low speed aerofoils running too fast] needed for thick rudder shafts.

I'm currently correcting  an assymetric rudder problem on my wheel steering 315 [2007]. The drag link arm was fitted [presumably by Hanse] is 860mm long, the tiller arm is keyed at 10deg offset. The correct setup is 5 deg key offset and drag link should be 780mm. The drag link cannot be set below 800mm long so the builder turned the tiller arm over fitting it with 20 degree offset, this makes the steering totaly assymetric.  I am currently correcting both these faults to get my steering corrected. I appears to have come out of factory like this. These type of faults do little to asswage my lack of confidence in yacht  design or build getting it right.

Regards Perry

not quite a rant but I feel better!

Yes your right the thicker sections stall later but more drag which is what worries the racing person.

the extreme high aspect ratio rudders seen on race designs with narow cord and thin sections parabolic plan forms maximise efficiency eg minimum drag for max lift, well they stall suddenly with little warning. Checkout some of Bekens broaching yacht pics.

Conversly the old barn doors hung on back of long keel or skeg mounted with little attempt at balanced aerofoil, great wide cord with little attempt at aerofoil sections dont really 'fly', so the difference between attached flow [flying] and stalled flow are hard to feel, and even when deep in stall may still help to push the stern sideways??

 kindly Éric

Finally I chose to modify my rudder. I cut it by 15 cm, changed the upper part and improved the profile... I hope my choice will be beneficial! I'll give you my impressions in April.

Éric