Hartely 30 with Lee Helm. Helpfull suggestions please

Discussion in 'Boat Design' started by Andy Turner, Aug 1, 2014.

  1. PAR
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    PAR Yacht Designer/Builder

    The first thing seems pretty obvious and this is to scale the drawings you have and check the mast location, it's height, fore triangle, boom, etc. If it's distinctly different, you can likely still use it, but you'll need to place it with the CE about where the original was supposed to be.

    Finding the original CE should be easy enough if the sail plan is marked, which is usually is. If not, it's an easy thing to work out anyway. A good guess is about 18" aft of the luff, at the second reef point on the main. The geometry is very simple if you want to be more precise.

    With an accurate CE drawn up, you can make a same scale drawing of the present rig, also figuring out it's CE and place this on the same vertical line the original CE was located. This will get you very close to balanced. So close, you'll be able to tweak with mast rake, which again, looks to be in the 2 degree aft range.

    My data on the design, doesn't have much on the bilge keels version's handling characteristics, but the fin keeler is said to do well. We can reasonably assume, she'll balance right, once the rig is balanced over the CLP, given an appropriate lead, which will be in the 15% - 17% range for this style of masthead.

    Yes, earlier I misspoke (typed). you want less area forward, not more, to ease lee helm and/or more lateral area forward. I don't think this is an appendages issues, so much as a cobbled together rig with poor placement kind of thing. Some drawing time, sitting at the kitchen table with a ruler and a pen, will yield close enough results to see how far off things are. Even at a fairly small scale you'll be able to nail things down to an inch or so, which is good enough.
     
  2. Andy Turner
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    Andy Turner Mr

    Thanks again everyone for your extremly helpful, and oftn amusing, comments and suggestions! I apreciate your time in reqding the thread and looking at the pics and data!

    Here is the current plan, after which i shall report back and let ya'll know the progress.

    1. Go to the boat on friday and definitely rake the mast back to the plan figure of 9.75 inches.
    2. Ideally look at moving the forestay mounting point back behind the anchor roller instead of the end of the sprit.
    3. Have a chat with Alan Robbinson the sail maker about the sails, their condition, shape and area and if he feels anything needs doing to them.
    4. Make very acurate drawings of the positions of eveything as rcomended by PAR to compare and calculate against the plan.
    4. Go out and try the boat with all that done and all the weight i put aft for grounding moved below to the saloon a central and as low as possible.



    Just out of interest, i know that in the ideal world i want to have all the weight in the boat at the C of G and as low as possible. But what is the score with trim and helm feel? Is it generally the case that too much weight at the stern adds to lee-helm feel? Or is it different with each boat and needs experimenting with?
     
  3. Skyak
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    Skyak Senior Member

    One suggestion I have is that you NOT do the work to position the forestay until you do the accurate CE calculation. Your boom is short, your mainsail is small, I don't see how you can think the original rake and forestay position will work. Do the calculation first. If CE is still off double digit percentage...

    About trim -my thought was that less bow in the water means less lateral resistance forward contributing to lee helm but get better opinions.
     
  4. PAR
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    PAR Yacht Designer/Builder

    Skyak beat me to it. Do the drawings and checking first, before touching the standing rig. It's probable you'll need to replace the headstay and /or move things around, so plan these out, so they can absorb the loads. Once the figuring part is worked through, you can develop a parts list and plan of action to get things moved once, for good. You've already seen what happens if you guess or just tinker with it.
     
  5. Andy Turner
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    Andy Turner Mr

    Good advice.

    So from the plan i have, i uploaded sheet 6 to an earlier post, i can work out the correct position for the CE, 18" back from the luff at the secon reef point?

    Then make measurements and drawings of my boat and work out where the CE actually is with my rig and sails.

    And then i know how to adjust my rig or if it is going to be adjustable?

    Is that rigt?
     
  6. SamSam
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    SamSam Senior Member

  7. PAR
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    PAR Yacht Designer/Builder

    Yep, 18" is a guess, based on this general rig type and it's proportions. In reality, it might be closer to 12" aft of the luff.

    With the "designed" CE located, place your current rig over the drawing and see if it "hits" (it will not). Next see if you can slide the whole rig, forward or aft to make the CE hit on a vertical line through the designed CE. This might require some wholesale changes, such as a bow sprit or the removal of a bow sprit, moving chain plates, stemhead fittings, etc., but on a steel boat this is easier then other hull materials. The only real issue will be mast compression at the step, which needs to be stout (really stout). With luck, you'll land on the bulkhead the mast was supposed to land and compression forces are handled. If not, a compression tube will solve it.
     
  8. Skyak
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    Skyak Senior Member

    Just to be sure, can you also measure the leading edge of the keel attachment relative to the bulkhead and that the mast step is directly over the bulkhead and centered in the stays. Someone would be crazy to move these but based on some other dimensions....
     
  9. Andy Turner
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    Andy Turner Mr

    Yeah i will. I will take measurements of everything on the boat and check it all against the plan.

    Overall length.
    Position of and dimensions of both keels.
    Position of mast step.
    Positions of all stays and shrouds.
    And if possible i will measure both sails to check they are what they say they are on the builders notes.

    Thanks again guys, so helpful being on this forum!
     
  10. UNCIVILIZED
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    UNCIVILIZED DIY Junkyard MadScientist

    Tag 4 further study.
     
  11. Martin B.
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    Martin B. Junior Member

    Unbalanced craft

    Andy, you have virtually all the answers you need in your own information.

    Firstly your mainsail is undersized and thus you do not have enough leech area to"push" your craft up into the wind.
    Look at the numbers. Luff should be 11.5m - your sail is a whole 700 mm short.
    The foot should be 3.96m - your sail is 123mm short.
    I went thru this same problem many years ago when the builder of my craft ran short of funds and just purchased stock already made sails from the loft, the main was way undersized - STUPID. We could hardly get the bow up towards the wind she had so much lee helm !

    Even before you get a new main, lower the boom down to somewhere where the designer intended it, this will reduce the heeling moment of your sail plan and thus slightly reduce you out of wack helm. Incidentally on my yacht I lowered the boom by about 600mm by cutting the bottom off the mast which was easier than trying to relocate the gooseneck assembly then I had about 1800mm added to the top of the mast and got a new main to fill the mast and the original boom length - she took off and no more lee helm.
    Now, luckily your actual mast is longer than originally intended by 500mm ! So you could actually add at least 700 + 500 = 1.2m to the luff of a new mainsail and probably more if you lower the boom to it's correct height.

    Immediately rake your mast back to vertical and have a look at things then rake it back slightly further as per the original design intention.

    Next, lose the " bowsprit" IMMEDIATELY and land the forestay at/on/ just aft of the stemhead ( depending on the actual structure at and underneath the stem) . This will bring the Centre of Effort aft somewhat. With a larger mainsail you will seem to be overcanvased much earlier - Fine, just douse the #1 headsail and hoist the next size down . Immediate result, less sail forward therefore decreasing lee helm.

    From considerable experience, which is written up in detail in this Forum - see "John Spencer's designs" post #95, changing the shape, cross section or whatever of a steel keel(s) and or rudder (I did both), is not a simple job. Start on correcting the sail plan first.

    Good luck and keep us advised of your progress.
     
  12. Andy Turner
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    Andy Turner Mr

    Progress.

    Right.
    Having spent friday on the boat her is what i accomplished.

    I took acurate measurments of the boat and have estblished thatt he mast foot is in exactly the right place.

    Ther is room for some adjustment of the mast foot to bring it further back if needs be, but the mounting plate is in the correct position.

    The keels and rudder are also correct to the plan.

    The forestay was attached right out att he end of the sprit so i have moved it backwards as shown.

    I didnt have the oportunity (tides, winda nd time didnt allow) to test her out, but i am very much hoping this has made a difference.

    Obviously if this works then i shall weld a steel web in the centre of the sprit so i can mount the forestay back in the centre, although i dont actually think having it 2 inches to the right will make any diffeence.
     

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  13. Andy Turner
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    Andy Turner Mr

    Having moved the forestay backwards 8 inches and tightened the shrouds and backstay i have now got a mast which rakes aft instead of forwards.

    I know its probably not the best method but with the boat afloat and everything below decks and low down i bolted a spirit level to a work bench on the car park, leveled it up and sighted it against the mast.

    If nothing else it establishes that the mast was definitely leaning forwards and now it is definitely leanign backwards.

    The next this is to see what differnce this has all made.

    I can still move the mast foot back a little as shown in the next picture but i am hoping it wont be necessary
     

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  14. Andy Turner
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    Andy Turner Mr

    More pics of work so far.

    In this pic you can see what i have done at the front.

    The forestay was attached right out att he anchor roller.

    Is was all rusted solid so unfortunately i had to cut it off with disk cutter.

    I can turn up an new nylon roller so i'm not too worried about that.

    I have replaced the anchor roller spindle with some stainless threaded bar for now.

    I have moved the forestay back 8 inches and drilled it through the double thickness steel at the back end of the "sprit" for now to see what difference it has made.

    In due course i shall obviously, weld a web in the centre and get the forestay back 2 inches to the left but for now this will give me a good idea of whether the issue is better.

    Moving the forestay back 8 inches meant i could tighten the backstay fully, and i currently have no more adjustment on the backstay threads, however, i have made a temporary backstay tensioner which pulls together the two lower parts of the backstay, where they come down to the transom, giving me much more versitike adjustment in the backstay.

    As can be seen by the other pics the mast is now clearly raked back.

    The plan says the mast head should be raked back by 9.75 inches.
    It was raked FORWARD.
    It is now definitly raked back, altouhgh i havnt been able to figur out a way of measuring how much.
    Either way, this has got to make some diffence no?
     

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  15. Andy Turner
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    Andy Turner Mr

    Another pic.


    Robbo the sailmaker also made good opuse of the day by making tmplats for a sprayhood, i think it looks cool in silver tarpulin actually lol ;)
     

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