Why a sailing dinghy's hull is so much heavier than a windsurf board?

Discussion in 'Sailboats' started by xarax, May 4, 2009.

  1. ancient kayaker
    Joined: Aug 2006
    Posts: 3,497
    Likes: 147, Points: 0, Legacy Rep: 2291
    Location: Alliston, Ontario, Canada

    ancient kayaker aka Terry Haines

    There is no such thing as a wind-surfing bank manager; that is an oxymoron. Where would he put the cocktail bar?
     
  2. xarax

    xarax Previous Member

    They are wind-surfing into their swimming pools...:)
     
  3. BWD
    Joined: Aug 2006
    Posts: 229
    Likes: 11, Points: 0, Legacy Rep: 128
    Location: Virginia, US

    BWD Senior Member

    in canuckistan, it is too cold!
    They fly to grand cayman ;)

    @xarax: a little dark or black humor is fine, by me... :D
     
  4. tspeer
    Joined: Feb 2002
    Posts: 2,311
    Likes: 282, Points: 83, Legacy Rep: 1673
    Location: Port Gamble, Washington, USA

    tspeer Senior Member

    I think a big factor is a board does not have to resist the heeling moments of the rig. The mast mounts to the board with a flexure or joint, which can only transmit force and not moment. The moment on the rig is resisted by the sailor's weight pulling directly on the rig.

    With a dinghy, the moments are transmitted to the hull through the mast step (cantilevered mast, ala Laser) or through the shrouds and forestay. The moment from the crew hiking out has to be transmitted forward as a torsion load on the hull.

    I was once sailing a Laser when the mast step became unbonded from the bottom of the boat. It ripped up the deck when the rig gave way. A board doesn't have to take that stress.
     
  5. xarax

    xarax Previous Member

    Thank you tspeer,

    If that is so, to reduce the weight of a dinghy further we do have to move towards the windsurf solution, don’t we ? And the "true and only" classic sailors would dismiss or ignore it right from the begining, of course. So it will not evolve any more...I have not seen the 1958 film, or pictures, of the Peter Chilvers invention, but, as it was using a rudder, I believe it really belonged to a class of watercrafts that are nearer to the classic sailing boat than to the windsurf boat. ( The port/starboard movement of the windsurf mast is secondary to its function. Windsurf inventor Jim Drake had even tried another solution without it, but the shallowness of the water made the lifting of the rig easier if it was fastened to the board through a universal joint, like the Darby s craft . It serves much more to the modern surfers nowadays, of course.) Could a modern variant of Peter Chilvers' boat be a solution ?
    I suspect that another reason is simply the width difference, and this is dictated by the less control the classic sailor has on the boom and his body and hull movements, than the windsurfer. While the windsurfer can pull and push the boom both ways instantly and directly with his hands, and move the centre of weight of his body instantly and directly with his legs, and so while he is dealing more with the overall balance of his boat, our poor classic sailor struggles with ropes and rods that don’t offer him anything stable to hang on, and crawls back and forth in an unnatural body stance trying to keep the mast as vertical as possible. So the dinghy sailor needs more hull stability, i.e. more width, and we know how quickly width of the hull throws the lightness of the hull out of the window.
    I have thought that if, on a dinghy ( ! ), we could put a swing rig, like Aerorig, we could control it with some tiller or wheel fastened to the mast.This would function also as a handle, a stable point from where the sailor could hang his body weight with both his hands The rudder controls could be integrated on the same tiller or wheel and function by another movement of the hands, the rotation of the wrists, for example (like in some Segway models.:) ) Such an integrated boom/rudder control could well help the sailor to aquire a quicker and more direct control of the boat as it imoves through the elements, - and to concentrate more on balance matters . A better balance of the boat means a less wide hull, so less heavy hull as well.
     
  6. bistros

    bistros Previous Member

    Sounds like you already know what you want, so go ahead and build it. Once built, you will quickly be able to prove your concept (or learn why it doesn't work).

    For what it's worth, I suspect you are seeing things only from an experienced board sailing perspective, and your understanding of high performance dinghy sailing may be academic at best. Movement on dinghy is much less inhibited as you are not bound to the boom and are free to move anywhere.

    It seems all your design choices keep returning you to your comfort zone.

    If I were you, I'd try to get out and experience a variety of performance dinghies & skiffs before going further down this path. It seems you are making choices and setting preferences without understanding the things you are dismissing. You'd probably have a lot of fun getting out sailing. I'm sure there is an active dinghy sailing scene there in Athens - so go experience things!

    --
    Bill
     
  7. xarax

    xarax Previous Member

    The same old board sailors / classic sailing boat sailors misunderstanding, over and over again ! :)
    I tried to say that the movements of the windsurfer ( and of its body 's centre of weight ) are facilitated from the way he is holding the rig, and have a more instant and direct effect on the overall balance of the board than those of his dinghy sailor friend ! :) So I can argue the opposite of what you have said : Movement of the surfer s body is much more effective ( than the movements of the dinghy sailor ) as YOU are bound to the rig and hull, and so THEY are less free to move anywhere... And as the windsurfer can achieve a quicker, better balance, he also can rely on a skinner - so much lighter - hull.

    P.S. My "understanding of high performance dinghy sailing " is not "academic at best", it is simply non-existing ! But, as I stated repeatedly in this thread, we are not talking only aboutf high performance dinghies in this world ( this thread included, as it belongs to this world, I hope) ! Actually, judging with the help of limited knowledge that I happen to have in some other fields of reality,( that still exists somewhere out there, as you also can observe :) ), I don’t think that a super light dinghy can be high performing one. And to dismiss, right out from the begining, any questions that dare to compare the classic sailing boat with the windsurf board, as nonsense coming from ignorant windsurfers, is not so productive I think...I have never managed to sail a Musto or Moth foiler, but I was sailing dinghies long before you were born I suspect, as I am so old ! :):)
    Having said that, I must also say that I enjoy very nuch the discussions on high performance sailing that you and other nice guys have in this forum, and I hope I can learn something out of them.
     
  8. bistros

    bistros Previous Member

    I've spent the last three years regularly sailing a dinghy with a modified sailboard rig. Wishbone boom, strengthened mast etc. The mast is set as free-standing much like a laser - able to rotate freely and keep the aerodynamic profile clean.

    I've dealt with tons of "traditional" dinghy sailors who are quick to tell you a board sailing type rig won't work. From personal, hands-on experience it does work, and it does work well.

    The naval architect who has developed the boat and rig is a close friend - this is his personal boat and I have free access to it. It is a much more pleasant boat for me to sail with my son - no boom hitting him and very comfortable as well.

    My point is that you would benefit greatly from introducing yourself at some local dinghy clubs - everyone is always looking for available crew. Going out and learning about dinghy sailing by doing it is the best way to appreciate why and how things work the way they do. I did my first board sailing in 1976 at a sailing school I was teaching at - and I loved it from the start.

    If you were here in Canada, I'd extend an open invitation for you to come out and sail with me. Since we are on different sides of the globe, please go have some fun on the water - after watching the Athens Olympics, I know that there are lots of opportunities for you to see how things work on the other side of the debate. Once you do, you will understand that things are far more similar than they are different, and that I'm actually on the same side as you.

    I'd love to see you design and present your ideas of a dinghy incorporating sailboard technology - I'm one of few people who have a lot of time in such a design - and I've helped debug and tune the design. Contrary to your thoughts, I do believe that a super light dinghy incorporating a sailboard style rig can be very high performing.

    Cheers,

    --
    Bill
     

    Attached Files:

  9. Hansen Aerosprt
    Joined: Mar 2007
    Posts: 62
    Likes: 0, Points: 0, Legacy Rep: 29
    Location: SF Bay

    Hansen Aerosprt Junior Member

    Cool boat bistro.
    Do you have any better pics?
     

    Attached Files:

  10. Chris Ostlind

    Chris Ostlind Previous Member


    Yeah, true, but where are the windsurfer's feet in all this?

    On the board?
     
  11. xarax

    xarax Previous Member

    Thank you very much Bistros. It is evident that it was me who misunderstood you, after all ! :) I would be glad to take advantage of your most generous invitation and sail with you in Canada...although I must admit that I am not used to cold water and dry suits, as CT 249 has noticed !
    I wrote a quite long description of what I am thinking of recently, but I pressed the wrong button twice and lost the whole text, so I decided that a brief exposition would be better !
    As I see in your pictures attached, you still control the wishbone windsurf boom exactly in the same way we control a classic rig boom , i.e. through the block and tackle system that involves main sheets, pulleys and ratchets. You can not push the boom the same way, with the same gesture, as you pull it, what is the first huge difference from what the windsurf board sailor is doing. You have one arm and hand occupied with the tiller of the rudder and another with the sheet of the boom, so you can not use them to help your body positioning and moving securely on the hull, which is the second huge difference from what the windsurf sailor takes advantage of.

    A classic single handed sailboat sailor can not :

    1. Use both arms, along with both legs, to move his body.
    2. Use both hands, along with both feet, to hold his body in any position required for balance.
    3. Use both hands to control the swing fin of the sail-fin that swings into the air current.

    But the windsurf sailor can !


    Trying to figure out how we could have the standing mast and the rudder of a dinghy while retaining the better control the windsurfer has on the balance of his body and boat, I thought of a fourth requirement. Here is the difference from a windsurf and the light narrow dingy I am trying to imagine: The dinghy sailor should be able to :

    4. Use both hands to control the swing fin of the rudder-fin that swings into the water current.

    As we were both sailing dinghies back in the old good days of the 60ies and windsurfing in the 70ies, we remember the how miraculous the mere fact that we could stand and sail on this narrow hull has appeared to us ! The windsurf board was in our eyes as a miraculous invention as the bicycle was in the eyes of the 18 century people, I guess ! If there are some elements in this craft that can be copied and pasted into the dinghy, I personally have no problem with it, not at all ! Nor will my son who, unforunatelly, is ready to recruit to the windsurfing camp...:)

    Cheers and thanks again.
     
  12. ancient kayaker
    Joined: Aug 2006
    Posts: 3,497
    Likes: 147, Points: 0, Legacy Rep: 2291
    Location: Alliston, Ontario, Canada

    ancient kayaker aka Terry Haines

    We need a metaphor! Really, the difference between the board and the boat is the difference between a motorbike and the car. ON the motorbike you'd better use your body weight sensibly if you plan for a long life, IN the car it hardly matters unless it's a go-cart, and even then only if you're in a hurry. Bistro's point is that you must use your body weight ON the board to stay upright: it is far less important IN a dinghy and it doesn't matter a bit what you do with your body with the average cabin boat, unless the lady has a good idea.
     
  13. Tanton
    Joined: Nov 2003
    Posts: 992
    Likes: 92, Points: 38, Legacy Rep: 294
    Location: Newport RI

    Tanton Senior Member

    Weight.

    The "Bee" boat weight is at 26kg.
     

    Attached Files:

  14. bistros

    bistros Previous Member

    Bill:

    The boat is Eric McNicholl's Quetzal (first revision, not the newer asym/trap boat).

    Eric is in the middle of website issues right now, but you can find more pics of this design here: Quetzal rev 1.0. I know there is a video up on Youtube as well.

    I love this boat. It is simple at first use, but surprisingly sophisticated when optimizing speed - playing the traveller to keep leech tension up and reduce twisting off. Very similar to the discussions surrounding the "Punk" design we saw on S/A.

    Some boats just seem to be magic on the water and this original Quetzal is the reason I had Eric design the Falco for me. My ten year old prefers to sail in the Quetzal over the "scary" Falco. Eric has also modded the original Quetzal to use a small asymmetrical spinnaker. Eric reported it was faster than Contenders on the water around the cans using the kite.

    --
    Bill
     

  15. Chris Ostlind

    Chris Ostlind Previous Member

    Isn't this entirely dinghy dependent? There's a long list of dinghies IN which nobody sails. It's more like all over the boat with most of ones body mass well outside the dinghy.
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.