Weather helm

Discussion in 'Sailboats' started by stuart_paget, Aug 17, 2007.

  1. stuart_paget
    Joined: Aug 2007
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    stuart_paget Junior Member

    Hi there,

    I know this is an old chestnut but I would like to describe my problem and thoughts and see how these go down. I have a 20' gaff yawl with 4' bowsprit and 4' bumkin, beam of 7'9" with draft of 2'3" keel up and 4'6" keel down.. With full main I quickly get serious weather helm in F3-4 winds with the mizzen furled. There is a lot of lead in the bilges and 4 ' swing keel. Reefing the main early helps a lot but slows the boat down and the weather helm kicks in before the lee rails even get a look at the water! Also on a broad reach the tendency to suddenly break off on a broach can be a little alarming.

    I would like to go faster with full sail with the weather helm dramatically reduced.


    The present rudder hangs off the transom on 3 pintles the last of which is fixed just aft of the propellor. It has been suggested that I need to to have a lifting extension on the rudder for more grip and more resistance to weather helm. I am about to experiment with a second headsail as an easy option to try and when new sails are being made this year I will be asking the saikmaker to peak the mainsail as high as possible

    Does this sound sensible?

    Stuart
     
  2. Bergalia
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    Bergalia Senior Member

    More depth to the rudder sounds sensible. Do you have a 'folding' prop - if not it may be a worthwhile investment as this could cause turbulence and loss of rudder grip. As to fiddling with the sail configuration - I'd try experimenting at the rear end first.
     
  3. jehardiman
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    jehardiman Senior Member

    First; what is the angle of heel when the weather helm kicks in? This may be a heel problem rather than a sail or rudder problem. Many short, shallow, wide vessel like to be sailed on thier feet, not healed over as the waterplane rapidy becomes asymmetric as heel increases, especially on a hull with a deep forefoot.
    Second, it sounds like you should have a staysail and a jib if the boat is 20' with a 4' bowspirt. Older rigs used more headsails than most modern sailors are used to. They also reefed earlier, as the sailcloth stretched out of shape sooner than modern cloth. I'll bet if you post a picture, we'll find the mainmast placed well aft and the mizzen just a riding sail, also an older trait.
     
  4. Bergalia
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    Bergalia Senior Member

    Good points Jehardiman. Maybe a 'stiffer' narrower jib 'Scotch cut' might solve the problem.
     
  5. stuart_paget
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    stuart_paget Junior Member

    Thanks,

    I'll try and get a picture posted over the weekend. Most pictures are taken on the boat which is not really the angle you want ! Weather helm begins without much heel. I am rigging up a staysail with a borrowed sail this weekend so I'll see if that makes a a big difference.

    Stuart
     
  6. Cliff Pope
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    Cliff Pope Junior Member

    As rule I believe you should not try to compensate for sail imbalance by adjusting the rudder - it ought to be possible to get the boat to sail herself on a straight course by fine tuning the sheets. Use of a lot of rudder creates turbulance and slows her down, apart from being hard work.
    You could consider:
    Trimming her down by the stern a bit by shifting some of the ballast
    Adding another foresail, if you don't already have jib and staysail
    Lengthening the bowsprit. (My 21 foot cutter build in about 1880 has 7" 6" projecting)
     
  7. alan white
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    alan white Senior Member

    Weather helm like that can be ameliorated by various changes. Cliff has it right that if the boat is light in the stern, the boat will want to round up. Trimming the stern down will also tilt the mast back, so your gains will depend on how much is achieved by a small drop in the stern. The suggestion to extend the bowsprit also makes sense.
    I'm surprised you're finding the strong weather helm with the mizzen furled.
    I would think the boat would be slightly in the direction of lee helm with the mizzen furled.
    Check to see the mast is at least vertical, and not back-angled by trimming the boat to sit exactly in its lines on calm water and putting a level to the mast.
    This is all assuming you are able to flatten the mains'l. A too-full main can cause some weather helm. Close-hauled, how flat can you get the sail?
    A fixed central position for the sheet attachment to the deck may allow just enough lift to cause weather helm. A traveller would then make the difference.
    Hull shape has a lot of influence. A unusually broad stern at the waterline and a fine-ish entry will cause the boat to progress from lee to weather helm
    and little can be done except to trim sails. A well balanced underbody should always make for an easy and consistent helm.
    Lastly, your centerboard may be too far forward in the down position. Once dropped fully, raise it incrementally untill the weather helm decreases while still allowing good windward progress. Mark the position and when the boat is out of the water next time, glue a block in place forward of the board to limit its final position further aft.

    Alan
     
  8. stuart_paget
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    stuart_paget Junior Member

    Thanks,
    Much food for thought here. I checked the mast rake and it is raked aft to try and put tension on the furling gear. I will try this evening to adjust the bottle screw in the furler to get the mast forward.
    The mainsail is old and needs replacing so probably isn't helping. I have no kicker and no horse at the moment with no vang on the gaff. The mainsheet, clew outhaul and halyards are the only controls for flattening the main. The horse is the first on the list for new additions. I know that tradtional gaffs have no kickers but they seem to be effective on some modern versions.
    I have a lot of pigs in the bow so could move some aft, the boat though is already floating with 4-5" of antifouling showing so perhaps more ballast is required altogether with more to be added to the stern.
    I could try putting tape on the keel uphaul at regular intervals to see what worked best. I adjusted the mechanism when I first got the boat to allow the keel to drop fully, perhaps that was a mistake..?
    I have rigged a staysail as an experiment although the halyard meets the mast at the same point as the forestay so the there is not a parallel luff to the jib which may not help that much but is better than nothing. Weather was too bad at the weekend to test it though.

    Stuart
     
  9. alan white
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    alan white Senior Member

    A combination of plumbing up the mast and returning the centerboard to where it was when you bought the boat (at least with a mark like tape, as you are doing---- you may wish to have the extreme forward position for light air windward work) should help a lot.
    Regarding the depth, which depends on inside ballast, look at your aft waterline extreme. If you see a shallow angle under the stern and more depth would significantly lengthen the waterline by submerging the counter a couple of inches, add ballast as an experiment. You may gain speed as well as better balance.
    However, the most fundamental thing you can and should do is to set the centerboard up correctly.

    A.
     
  10. Flumixt
    Joined: Oct 2006
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    Flumixt Junior Member

    Stuart-

    Don't know if this will help but it may jog your thinking:

    I've got a 21 footer with 6 foot bowsprit. I can set one of several jibs on it. The smallest is 4 X 8 = 16 sq ft roughly. I set that out usually as low as possible but not always and it helps the helm lots. I can sail heeled over nearly 40º without XS helm going to windward. So it is really a steering sail. Usually I set it with a club so it self tacks. I think, but can't recall right now cause I don't sail this boat much anymore, that a larger flying jib (like 8 X 16) would be more effective on a broad reach.

    I do contol the helm also by maybe 1 tuck in the main and setting an extra jib of equal area to that reef. So effectively I have maintained the same sail area but moved it forward. Its a compromise, of course, but helps steering.
     
  11. stuart_paget
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    stuart_paget Junior Member

    Thanks,
    I have managed to put maximum adjustment on the forestay bottlescrew but the mast is still slightly raked aft. I have today bought a douglas fir timber which is going ot be a new bowsprit 400mm longer than the existing one. I intend to plumb the mast and to put a masthead forestay on this to make the staysail more effective by moving the jib further out and maintaining a parallel leading edge.

    BY marking the keel uphaul I should find the best balance. The winter project will be creating better profile on the rudder and if funds allow getting a folding prop. A kicker will also be added soon and a decent horse for the mainsheet, if all of this doesn't help drive the boat to windward the only solutiion will be a different boat...!

    Stuart
     
  12. alan white
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    alan white Senior Member

    Stuart, do you have any photos of your boat?
    No reason besides a love of gaffers.

    A.
     
  13. stuart_paget
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    stuart_paget Junior Member

    Photos

    Please find photos,

    I have no decent off boat shots yet but I hope you get the idea.

    Stuart



    oga 022.JPG

    oga 026.JPG

    oga 031.JPG

    boat launch mediaevil fair 033.JPG
     
  14. alan white
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    alan white Senior Member

    Thanks. Looks like a lot of boat. Looking at the hull, it appears to be multi-chine plywood. How do you like the lug mizzen? Is it handier than a gaff?

    A.
     

  15. stuart_paget
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    stuart_paget Junior Member

    Yes plywood construction epoxied below the waterline. The balanced lug requires just one uphaul so setting is pretty fast and the less time spent looking in the wrong direction the better! It might perform better than a gaff mizzen becasue it has less vertical luff and peaks quite high but that is pure conjecture on my part. Once I have my staysail to give a bit more pressure forward I will try beating with the lug set and see how I get on.
    The forestay is being shortened this morning so I should get the mast at least vertical and we'll see what a difference that makes.

    Stuart
     
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