Weather helm on half tonner

Discussion in 'Sailboats' started by nemo, Oct 12, 2009.

  1. Paul B

    Paul B Previous Member

    Ha Ha, my dogeared copy of the rule went into the bin in 1988. Now I wish I had kept it, with all the revised sections neatly glued in over the old text.

    Yes, the Rule did make designers jump through hoops, hoops the designers caused the rulemakers to put in because they would push everything to the limit.

    The skegs had to be measured in every dimension, a joy for the measurers. Even the radii of the edges of the skeg had to be measured to ensure they were legal skegs.

    People who never had to deal with designing or measuring to the IOR Rule have no idea just how technical little details like skegs and P brakets could be. The designer had to get it ALL right, every little detail. So did the builders.
     
  2. Paul B

    Paul B Previous Member

    The dashed line in the detail picture I posted is the CL of the rudder post. All the area in front of that is counterbalance.


    If you are able to make a thinner post and rudder you can shorten the chord length along the entire rudder, so a deeper rudder should not have any more wetted area than the existing one.
     
  3. booster
    Joined: Apr 2009
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    booster Senior Member

    Gary B!
    Thanks for the Wave-rider analysis. So they stepped a new mast. Yes, those holes are irritating, especially on the long offshore race. How to come out of those in decent shape... By the way I have been struggeling with those "merde" ******** as well.
    Regards,
    Booster
     
  4. Charly Setter
    Joined: Apr 2007
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    Charly Setter Junior Member

    Is this the Wave-rider you are talking about ? http://tinyurl.com/ygveh2n

    Second place IRC 1/2ton Championship 2009 in Belgium.:)
     
    Last edited: Oct 15, 2009
  5. Paul B

    Paul B Previous Member

    This is a crude outline (MS Paint over the existing Farr drawing) of what I was trying to say.
     

    Attached Files:

  6. Paul B

    Paul B Previous Member

    Yes, that is the boat.

    Note in the photo the boom is sheeted pretty much on CL, going upwind nicely.

    Note the angle of the tiller. Hmmm, looks like pretty neutral helm. No sign of "buckets" of weather helm on this IOR boat.

    Doesn't look like they need to "feather" the main.

    Doesn't look like they've had to reef in this light air to balance the boat.
     

    Attached Files:

  7. waikikin
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    waikikin Senior Member

    Nice picture, looks like a nice day out in light conditions. All the best from Jeff.
     
  8. Perm Stress
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    Perm Stress Senior Member

    "No sign of "buckets" of weather helm on this IOR boat"

    There is just barely any wind.... what weather helm in conditions this light ?!

    As to the "loads" weather helm...

    Good example is old Carter 30 halftoner, if not superchampion in class, but produced in great numbers in Poland some decades ago. For many dacades it was the only real alternative for ex Olympic sailors of Soviet part of the world. They were raced no less aggressively, as dingy classes their crews were originating from. Masthead rig with large genoas. Full depth skeg forward of her rudder. Stern lines somewhat similar to sailbag stuffed full, and open end then pulled tight with rope. Her tiller is ~80x80mm in cross section for good reason: two hands are not always sufficient to helm her in stronger conditions, no regards to the heading relative to wind! And yes, at least when cruising, they often reef the main deliberately and early. (all these developments made before introduction of full battens, really stiff sailcloth, etc.. I do not talk here about top budget world lewel racing; on our side of Iron Wall many technical advances in sailing were not physically present for long time, except only for state-supported-top-level-Olympic sailors.) At one occasion I even noticed a cruising oriented boat of this type with brand new suit of sails, with main 1-1.5m short on the mast, when fully set.
    That is one part: there WERE IOR boats with excessive helm.

    Then one more half penny:

    In Lithuania there is an RS280 racing monotype -~28ft long keelboat -a Toy used by ex-Olympic sailors to prove once again they arte still string and fast under sail. Why I mention it is because all of them have pretty normal weather helm upwind, except one -which have sails from different supplier this one, with appearently same mast rake and sail trim has definite lee helm...

    That is part two: sails could make HUGE difference.
     
  9. Brent Swain
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    Brent Swain Member

    Much of the weather helm common in so many racing boats comes from grossly unblanced hull shapes which tend to go down in the bow , and rise in the stern when well heeled, due to excessively wide sterns and excessively lean bows. A bustle tends to help by moving the centre of gravity further aft. Twin rudders well angled outward may give you more control.
     
  10. ancient kayaker
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    ancient kayaker aka Terry Haines

    One would expect excess sail carried too high to press the bow down, too. Not a racer or sailor myself (yet - but I'm working on the sailor part) but when I watch videos of ocean racers they seem to spend an awful lot of time with water hosing over the cockpit from forward. I suppose that is all part of the life of a racing sailor, but it would use up energy to do that.
     
  11. barrynelson
    Joined: Nov 2009
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    barrynelson Architect

    weather helm

    Hello

    I sail a 1980 model 3/4 tonner (albin stratus/Norlin36). Phenominal boat all things considered. Over the past 10 years, through many subtle changes she has gone from beast to well-mannered greyhound. Sail design, rudder design & weight distribution worked the magic. After spending the previous 25 years racing E-scows & Star Boats I had experienced the power of tuning.

    The first improvement was to remove everything from the bow. I tore out the water tank, got rid of the chain & big anchor, moved the batteries back etc. This made a huge differency in the tendancy to wipe out.

    The second, was a new rudder. The old shaft was slightly bent & bound-up in the bearings. The replacement, is a fully devleloped, carefully designed lifting surface with gimballed bearings. The new rudder provides two finger steering in ALL conditions with no back-lash & nice feed back. I rarely move the wheel more than an inch when things are in the groove. Very subtle & precise.

    The final big improvement was the new mainsail built by Chris Nielson Of Nielson sailmakers. Very flat, draft forward & dead flat in the leech area. Two top battens, just like the Star. One super stiff & streched tight for heavy air & a soft tapered one for light-medium. The previous main was soft, with draft way back & deep camber ... blown out, just like a worn out Star main.

    The difference between two identical Stars: one, with old, soft, blown out main & the other, a new firm, well shaped one is the difference between two completely different boats. One cranky, the other .. close to perfection. I am not aware of any boat which demonstrates the relationships of steering, sail shape & tune-ability like the Star. For those who haven't experienced the magic of Star boats, I sugest you try it. A friend of mine who is a world class Lightning sailor, spent a couple of years playing with an old Star just to learn about sail shaping.

    Hope this wasn't too long winded

    Barry
     
  12. booster
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    booster Senior Member

    Regnbågen

    Hi!
    I the previous post the Norlin design Stratus was mentioned. A development "Regnbågen" won the 3/4-ton cup about 1-3 years later. The championship was held in Denmark or Germany. The boat was sailed by the Sundelin-brothers (Olympic champions in 5.5 in Acapulco). Probably the whether-helm was cured with this development. However, this must be one of the last heavy-displacement 3/4-tonners to win the title.
    Regards,
    Booster
     
  13. Brent Swain
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    Brent Swain Member

    Raking the rudder post aft drastically reduces its effectiveness, as this tends to suck air down it, causing it to cavitate early . Raking it the other way tends to draw water up it's lee side, making it more effective and less prone to stall, as long as you don't rake it too far.
     
  14. DasHearach
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    DasHearach New Member

    Weather helm on 1/2 tonner

    I had a lot of fun with friends who had a 1/2 ton Whiting in Singapore 1980 - 83. This boat had serious weather helm problems when I was offered the helm. I quickly handed the tiller back and told the skipper to steer straight. I then steered the boat using the main sheet. We then started winning races! In case anyone was there the boat was called "Big Splash".
     

  15. citrus76
    Joined: May 2012
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    citrus76 New Member

    Apologies for posting on such an old thread. I own a Farr 920, (design 54). I found this thread while looking for information on modifying IOR sterns...I believe that Nemo's original post refers to design 65 which followed on (and beat) design 54. After reading through this thread (at least the design parts of it) I thought readers may be interested to know of my experiences of some modifications I have made over the years which have been done without really knowing what I am doing... I was quite surprised to see them all listed here... Rebuilt boom - length increased by 350mm. Can confirm this didn't alter balance, but did help with down wind performance. Reduced mast prebend and slightly increased rake to account for new sails (which made a huge difference).
    The single biggest improvement though has been to modify the rudder. On the advice of others I 'had a go' at adding 30mm to the leading edge and increased the depth of the rudder 150mm. I also reduced the chord as much as I could using the original rudder. Of course this is more drag (and hasn't altered the underlying balance issue), but combined with the sails and better trimming has made an enormous difference in terms of better grip / control. The weather helm is massively reduced in breeze over 20kts. I used to be terrified flat off in 20+kts with the kite up trying to keep the boat 'on its feet', now if we tip over, it's all my doing... There doesn't appear to have been an appreciable light wind penalty either.
    The rudder modification was made slightly half heartedly, as I didn't know whether this would be a good or bad thing so wanted to be able to 'grind it all off' if it didn't work. For anyone else with this type of boat / issue I think I can recommend the new rudder option. Definitely a success.
     
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