New Dory Rig: Lug-Yawl

Discussion in 'Sailboats' started by Clinton B Chase, Jul 25, 2008.

  1. Clinton B Chase
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    Clinton B Chase Senior Member

    Greetings,

    I am working on a couple design projects, my Maine Coast Dinghy that I have mentioned before, and a new rig for the Alpha-Beachcomber Dory. Attached are scans of the sketches, the sail plan and another plan showing interior layout.

    My question regards balancing the rig. My aim was to keep the C/B box in the same place for simplicity and so that the traditional dory rig could still be used interchangeable with the drawn lug-yawl. I found the CE for my rig and the alpha rig and they are shown as hatch marks on the baseline. Notice how far aft the CE for the alpha is! It is aft of the CB. I was taught to get the CE to fall on the leading edge of the CB and you'll see that is where it is located as I've drawn it.

    Could anyone suggest why the CE is so far aft in the original. Any dory sailors here who know whether these boats had a lot of weather helm, which I would predict based on this analysis. Suggestions for where I should get the CE to fall would be appreciated. THANKS for checking out this new arrangement.

    Cheer,s
    Clint
     

    Attached Files:

  2. alan white
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    alan white Senior Member

    Hi Clint,

    Could be the fact that the CE moves forward when reefed, and a tender boat like a dory reefs sooner. This puts the CE where it should be in heavier conditions. I am guessing however.

    Alan
     
  3. sharpii2
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    sharpii2 Senior Member

    Why not make the mizzen slightly bigger?

    And why not make it with a sprit boom instead of a Bermuda one? Then it would always set right and not twist.

    You probably would not have to enlarge it much, as you are very close, as it is (going by the distance between sail area centers, NOT the board.). I think the mizzen would still be small enough to entitle you to call the rig a yawl, as you might be increasing its area by 20% or less.
     
    Last edited: Jul 28, 2008
  4. alan white
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    alan white Senior Member

    Looking at it again, I think you should go with your plan and allow for some adjustable rake (aft from plumb) with the main mast. The addition of the mizzen allows helm correction by sheeting it flat. It's a nice looking rig and handier than the original rig. At worst you'd have to move the mizzen aft and add a V boomkin. The socket for the mizzen mast could be halfway up the transom board.

    A.
     
  5. Clinton B Chase
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    Clinton B Chase Senior Member

    TX for thoughts: Alan per you first response, the dory-alpha rig was rarely reefed, they used different rigs and dropped in the most appropriate size before pushing off the beach (the fishermen) or shoving away from the dock (Beachcomber club racing in early 1900s). My latest though as to WHY the CE is so far aft is that it would give some weather helm, enough to give the yoke-line steering system some 'positive' feel.

    Yes, making mizzen a little bigger would bring my CE aft. I need to really determine if I want to do that. I'd like to get this thing balanced on paper and not be rebuilding the partner area...but that would work to slowly rake the mast(s) to get the CE where it feels good. I may indeed use a sprit-boom on the mizzen...I thought with its size and the sheeting angle that the boom with jaws would be better, but maybe not.

    The other big Q is to decide if 102 + 18 SF is enough. I think it is...what about a mizzen staysail on this rig?

    Clint
     
  6. sharpii2
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    sharpii2 Senior Member

    Hi, Clint.

    Some more thoughts on your dory rig.

    Maybe you would be better off without a sprit boom. It can be a bit of a hassle to set up.

    I can think of two alternatives:

    1.) putting a vang on the Bermudan mizzen. This can be very simple and does not need to be adjustable. It merely keeps the boom down as the sheet is let out. The sail should be cut flat anyway, as its main purposes are to trim the balance, meaning it will be feathered a lot, and to act as a riding sail at anchor. the other alternative is:

    2.) using a boomed lateen sail. With this sail, you can make the yard longer than the boom and move the CE aft that way. This sail would not require a vang to hold the boom down, just a hold down strap. The only disadvantage would be that there would be three spars rather than just two. But all of them would be shorter than the mizzen mast with the Bermuda rig. The shorter mizzen mast for the lateen could possibly be left permanently stepped, as it wouldn't offer much windage.

    I think you have enough sail area, even excluding the mizzen from the calculation.

    What you have here is a long, narrow boat that is also quite tender. Such a design (without a lot of outside ballast) is not good for light wind sailing, anyway, and probably should be rowed in those conditions. The sail rig should be for times when the wind makes rowing a hassle. Then, a smaller rig comes in quite handy. It isn't instantly over powered by the winds it will usually be sailing in, say 10kts +, and the spars are shorter so they take up less room when not used.

    With this type of boat, as with just about any sail boat, a weather helm is far superior to a lee one. This boat, being long and tender, would be quit mean with a lee helm. The original rig probably got the balance right as a boat this narrow and symetrical should have very little Leed, if any at all. This may well be an exception to what you were taught.

    Just a few thoughts.

    Bob
     
  7. Clinton B Chase
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    Clinton B Chase Senior Member

    Good points. I am a bit locked into using this lug b/c it is a sail I would use on a skiff I am planning to build soon...the idea is to use the sail for two different boats and save a lot of money, time, and kill "2 birds with one rig". I also happen to think the lug is the most elegant of all rigs, this one especially. So the rig is locked in. I have two places to play around: 1) size of mizzen/placement 2) rake of foremast and thus it controls CE location greatest. I think you are spot on about rowing in light stuff and setting up the rig once the wind is up to 10kts or so. She'd also be a bit of a dog in light air b/c she'll weigh a lot as dories often do! Upon reflection I'd build a mast partner to except the lug rigged alone and rigged with the mizzen.

    I'd like to have a rig that I can fly a mizzen staysail for off wind cruising especially in light airs. I wonder if my arrangement can take this sail as drawn.

    Cheers,
    Clint
     
  8. sharpii2
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    sharpii2 Senior Member

    mizzen staysail.

    Hi, Clint.

    I suppose you could put a relatively light one on and maybe gain a dozen or so square feet.

    Your mizzen is not very tall, so anything bigger would have really goofy proportions.

    The mizzen mast might have to be made with a bigger section as it would have much more load on it.

    It would be a handy way to move the CE aft, though.

    The luff of the sail might need a little hollow cut into it, as there is really no way to stay the mizzen to hold it tight, but I think that by the time the wind got strong enough to make that something to worry about, it would be time to take it down anyway. The hollow would make it behave better.

    Bob
     
  9. Clinton B Chase
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    Clinton B Chase Senior Member

    Latest sketch

    A new take on an old boat...
     

    Attached Files:

  10. sharpii2
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    sharpii2 Senior Member

    Looks like a vastly improved boat.

    Hope it works as good as it looks.
     
  11. diwebb
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    diwebb Senior Member

    Hi Clinton,
    another option is a balanced lugsail cat schooner/ketch rig (both sails the same size). I have used this rig on a dory and it worked very well. I originally designed it for a 14 foot multipurpose dinghy I designed, see attached sketch. You would need to step the foremast as far in to the bows as possible and the aft mast at about the aft end of the centerboard case. The balanced lugsail is self vanging and you could design for light air and then use one sail relocated to the forward end of the CB case for heavy air. The rig works very well downwind wing and wing and you can run with the foresail by the lee in a quartering breeze. I once beat a Thistle with this boat in about 10 knots of breeze.
    Just a thought to mix it up a bit!!
    All the best with the project.
    David
    Having trouble attaching the sketch will try again in a new reply
     
  12. diwebb
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    diwebb Senior Member

    Hi,
    this time I managed to attach the file.
    David
     

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  13. Clinton B Chase
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    Clinton B Chase Senior Member

    David, Thanks for the thoughts. For my dory, having the sails way in the ends of the boat would make sail handling difficult in a seaway. Here you see my current sail plan; the lug and mizzen are as far in as possible for the reason mentioned and simply because of the fact that this dory is so damn long...it takes a minute to get from one end to the other! So the sails are handy. Also, I have enlarged the lugsail to be about 122 SF which should be plenty...it should drive the boat when loaded and deal with getting her through chop as well as spread enough sail for off wind work. When lightly loaded, I will put one reef in as a default....to bring the area down to 100 or 105 SF. The centerboard is pretty locked in now as is the middle thwarts...the second aftmost thwart must stay put for this is the place the boat trims perfectly when rowing solo, which is fun if the boat is light and wind/seas are relatively calm. I'll carry 50 lbs each side of the trunk as essentially permenant ballast. I MIGHT move the mizzen aft a touch but this picture will simmer a bit before any final changes and larger scale drawings commence. This has been more work than I thought, but a lot of fun, too. I'm sure this arrangement has been done before, but I have not come across any documentation of such work. Perhaps if the 'net had been around in the day there would be a lot of models to go on!

    Clint
     

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  14. sailing canoe
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    sailing canoe Junior Member

    joel white 18 ft dory

    Hi Clint, Hope the wrist is back to work. On another thread i saw that you had Got the plans for the joel White 18 ft Shearwater. I saw one last weekend and really liked it. I wonder what you thought of it and if it played any part in your dory? Of course I always want bigger which your Dory is -- Nick
     

  15. Clinton B Chase
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    Clinton B Chase Senior Member

    Nick I have seen the 18' joel White boat. It is really a modified faering, sort of dory hybrid. It is very nice. Sails and rows well, sails better the owners tell me. I decided the look didn't suit me once I saw it on the water, but it has grown on me. It is a narrow boat and needs a mizzen I think to be a good sail and oars boat. Making this mod is doable but requires some drawing like I have done above. It played no role in this dory, which is not my design but a Chamberlain Alpha-Beachcomber redrawn by Gardner. i traced the lines and redrew the interior. Looking at this now, I would make the mizzen high aspect and move it aft. I also now think 105 is too little for the lug. It needs more along the lines of 120-125 SF, I think, for this big heavy dory.

    Cheers,
    Clint
     
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