drawing needs scale

Discussion in 'Boat Design' started by sandpiper32, Aug 28, 2014.

  1. NoEyeDeer
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    NoEyeDeer Senior Member

    Can you get a strong enough fir mast at a decent weight inside the original partners?
     
  2. Rabah
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    Rabah Senior Member

    Hello All,
    Please to see attached files
     

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  3. PAR
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    PAR Yacht Designer/Builder

    The masts were simply extruded aluminum (6061) tubing, though I don't have the diameter and wall thickness (not a difficult set of calculations BTW), they'd likely be considerably lighter, even as contiguous sided tubes, in this size than a birdsmouth spar, especially if made from Douglas fir, which will be 20% - 30% heavier than more traditional spar building species.

    Rabah, is slowly developing up a hull, which makes one wonder why, though now has produced a set of triangles, similarly placed over his hypothetical hull. Nothing in these new "sail plan" drawing are particularly helpful, in fact little more then a tracing with a really big magic marker. Not that it isn't a noble enough effort, I just question its need.

    What would be helpful Rabah, are appropriate set of mast scantlings, their placement over the actual CLP, with a justifiable lead (for this type rig) and possible sail maker details, such as the appropriate amount of luff round, leach, batten count, etc., not to mention the associated hardware details with their customary callouts, rigging considerations with accurate lengths on the proposed tackles, etc.
     
  4. frank smith
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    frank smith Senior Member

    Sailrite , might have some info
     
  5. Rabah
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    Rabah Senior Member

    Hi All,
    Again a new portion of laughter and an entertainment!
    PAR again hopes to change the controversy from the basic / first / problem OP - whether there is a possibility to copy drawings or photographing of a small format / usually from the Internet / thus that we could measure our construction then.
    I am already tired will explain with my poor English language. But I think that language of engineering is the universal. If the interlocutor truly the professional he will understand you also with smaller words.
    What for it is necessary to deflect the subject to mast rigging? It is a new subject for new thread.
    What for so irritates you model which I has made? It was not without the purpose. He was necessary! Without it the method of program Delftship Professional would not show any outcomes.
    It is banal to iterate. But it is necessary to be clarified. How I have made all?
    I had L hull and B max. On them has picked model - contours without meaning. Whether on the slightest meaning there will be they type Presto or not!
    Scaled the image on principal dimensions L and B.I was then subordinated contours of my model on contours of the image.
    After that it is already easy. In the upper right of each projection there is a window for coordinate of each point of the image.
    I have already shown you the sails. Certainly I not credulous to calculate only to drawings published from Frank Smith. To compare outcomes I was used one more image of a lateral view at the yacht with sails - photographing from the brochure for Sandpiper 32 in the Internet.
    Gross area of sails it is received under the drawing 31,746 m^2 and on photographing 31,88m^2. But also in two cases it is impossible to be 33,72 m^2/363 ft^2/.
    And other sizes for you / see the coordinate system from the file in the former publication/:
    Location of the propeller at the stationary engine: X=1,623m from Zero point; Y=0 and Z=0,143m from BL
    Main mast – coordinates on a middle line of mast:
    Down end X=5,167m from Zero point; Y=0 and Z=0,154m from BL
    Upper extremity X=4,408m from Zero point; Y=0 and Z=10,58m from BL
    Fore mast -coordinates on a middle line of mast:
    Down end X=8,872m from Zero point; Y=0 and Z=0,389m from BL
    Upper extremity X=8,342m from Zero point; Y=0 and Z=10,62m from BL
    Down end of the side keels - fore edge: X=5,886m from Zero point and Z = - 0,902 m from BL
    Check of Maximum Navigation Draft with side keels: Z keel + body draft =0,902 + 0,467 = 1,37m for WL by Displacement 3,356t/7400lbs/.
    It corresponds to published size Draft-Board Down = 4 ' 6 '' =1,3714m
    Centre of the toilet sink - upper extremity: X =7,862m from Zero point; Y=0,375 m from CL to PS and Z=0,685m from BL
    Only it is not necessary to ask me about the diameter and the thickness of tubular aluminum masts. Each designer respecting himself will evaluate these constructive sizes if will be engaged in it.
     
    Last edited: Sep 16, 2014
  6. Mark Fisher
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    Mark Fisher Junior Member

    I sail hull #24:
    [​IMG]

    The boat as designed was a schooner rig. My PO built the boat in MA from a "hull kit" and swapped main for mizzen (and moved the mizzen step aft ~3 feet), but kept the rotating mast rig. It is quite convenient, though not as close-winded as a sloop.

    The masts are tapered aluminum. Diameter at the deck is 6 inches, tapered to around four at the top. I don't know the wall thickness offhand. They weigh ~100 lbs each. I dream of having carbon sticks made and shedding ~ 400 lbs of lead ballast at the same time.

    I have some of Walt's construction drawings, though no layup schedules or other construction details. Getting enough information to fabricate the masts from the brochure drawings would be a stretch!
     
  7. Rabah
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    Rabah Senior Member

    Hello All,
    This time I shall to quote myself:

    I shall add only, that coordinates lower and peak points of masts which I have shown, determine their length. It will facilitate work of the designer which will occupy in calculation of necessary cross section /or the minimal secant modulus on a bending / of aluminum masts. They are subject on a bending from wind stress on sails. Obviously masts will consist on a length of the several pipes of an aluminum alloy welded to each other with different diameters.
    It would be very useful if Mark Fisher published those drawings with which he have.
    But from photographing which Mark published it is visible that sails are three, instead of two as was in drawing Walt Scott. It suggests me the following:
    I have received for two sails a gross area responding drawing of Walt Scott 31,746m^2. But size is specified in drawing of Scott 363ft^2/33,724m^2/.
    Probably that the third /most fore/ sail have the following area:
    33,724-31,746=1,978m^2 ≈ 2 m^2
    It would be interesting to see how much there is the area of each of three sails on yacht of Mark Fisher.

    At last I want to congratulate all readers of the forum on the coming New 2015 and to wish them many health and happiness.
     
  8. Mark Fisher
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    Mark Fisher Junior Member

    As I recall, the masts were alum. flag poles. They are tapered, not welded. I'll get back with sail areas. That blade jib comes in if the wind gets above 10MPH!
     
  9. Rabah
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    Rabah Senior Member

    Hi Mark Fisher,
    It was difficult to trust that on the length of the aluminum mast there is no any welding provided that a diameter for the deck is 6 inch / 152,4mm/, and in the top is 4 inch/101,6mm / as you have said.
    I think the conic rolling pipe it very dearly costs as alternative for manufacturing.
    Whether you will publish any drawings or this is just talking?
     
  10. DCockey
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    DCockey Senior Member

    My understanding is tapered aluminum poles are/were used as masts in Marshall catboats. The poles are/were made from straight tubing and tapered by a "spinning" process. The poles are relatively inexpensive as they are produced in volume for use as flag poles and for supporting lamps along streets and in parking lots.
     
  11. Mark Fisher
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    Mark Fisher Junior Member

    Again, my boat does NOT have Walt Scott's intended sail plan. Instead, the masts were "swapped," and the taller mast stepped forward in a Ketch configuration. It balances fairy well. The jib is a strictly light air addition (under 10 MPH on deck) as there is no bobstay for it - I've splintered one jib boom already! The jib boom is run out when needed and housed at dock.

    The masts are 6" dia at their base. Mizzen has a 5' bury and rises 23.5' above the deck, while the larger main has a 4.17' bury and rises 26.3'. Booms are doug fir.

    Sail areas are approximately: Main, 170 Ft sq, Mizzen 140 Ft sq, Jib under 100 Ft sq. Can't measure them now, as they are at North's.

    I have a copy of Walt Scott's line plans, but not of his rigging plans or layup specifications.
     
  12. Rabah
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    Rabah Senior Member

    Hi All,
    To calculate efforts acting on the mast of a sailing yacht and to construct it / to pick a profile of cross section, length, to bracing to the hull / all this is not at all easy problem.
    Let's see what is written in old books. For example in “Modern Development in Yacht Design”, David Cannell and John Leather, 1976, Russian translation 1979.
    On picture 5.1 the main forces acting on the mast are specified /see Fig 1/.
    At approximate calculations the distributed lateral load from the sail neglect also the mast calculate only for perception of thrusts from rigging, i.e. it is counted on stability by Euler formula /see Fig 1/.
    On picture 5.3 you will see sections of masts from different materials/see Fig 2/on same Euler loads:
    1- Fiber-glass-reinforced plastic / wall thickness 5 mm/
    2- Al-mag alloy / wall thickness 3 mm/
    3- Stainless steel /wall thickness 2 mm/
    And citations from the book “Yacht bau”, K. Reinke, L. Lutjen, J.Muhs, 1976, Russian translation 1982:
    „ The masters manufacturers of metallic masts have empirically received data /in the simplified tables/ in which a basis for calculation of cross section of the mast are only the length and breadth of the ship, displacement and sail area. “
    ________________________________
    NA Razmik Baharyan
     

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  13. Rabah
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    Rabah Senior Member

    Design of Yacht Mast

    What it is necessary to make the professional projecting a mast for yacht to convince the surveyor of Classification organization that it not be damaged at a strong wind during travels?
    From Rules GL for Yacht up to 24m, 2003, Part 3, Section 2-Mast and Rig, we can see following:
    1.1 According to the development of computation methods GL examines mast and rig dimensioning
    through geometric non-linear finite element analysis (FEA).
    2.1 Normally, four sailing conditions upwind and one spinnaker case are considered, all at 30 ° heeling angle of the yacht.
    3.2 Loads in longitudinal stays and halyards also contribute to mast compression. As a general approach this contribution to mast compression will be brought into account by 85 % of the maximum load at the mast step of the four upwind cases and is to be added accordingly to give the maximum total load.
    3.3 Buckling load will be calculated observing the contribution described under 3.2. As a requirement for sufficient stiffness buckling load must be at least a factor 2,6 above the maximum total load.
    All this is difficult enough for calculation. For this purpose I bring to your attention one very simple and light formula for calculation of the Inertial moment of cross section of a mast for yachts from Dmitry Kurbatov's book „ 15 projects of vessels for amateur construction “, 1985.
    The formula is approximate and it is possible to use even when the Diagram of righting arms misses.
    I regret that I cannot offer you the text in English for these formulas. All the same I am not a professional translator. But I think that formulas can be understood and without specialized translation.
    In the picture 201 you can see the longitudinal section of a mast at armament with a mast head staysail.
    ___________________________________
    NA Razmik Baharyan
     

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  14. sandpiper32
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    sandpiper32 Junior Member

    Mark Fisher, you mentioned you had a lines plan of the sandpiper 32. I'd love a copy for my files. I've two carbon masts that I intend to re-rig with. Currently i have two Soling mains on tabernacles. Love my boat and intend to get her to sail better upwind.
     

  15. Mark Fisher
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    Mark Fisher Junior Member

    The lines are in DXF format. In 2001, I left the original blueprints out in the sun for a week, and they were damaged. I then scanned them and used Turbo-cad 2D to re-synthesize the lines. The original blueprints and the original scans have both been lost. I can give you either DXF or TCW formats.
     
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