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Thread: An Ilur in Vermont

  1. #351
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    Default Re: An Ilur in Vermont

    Thanks for posting that pic. Also eliminates a potential leak-point past the C/B shaft, I suppose.

    Very clever.
    Sooty Tern Build Thread: Another Tern in the Works!
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  2. #352
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    Default Re: An Ilur in Vermont

    I'm guessing that since my Beg-Meil has a metal CB, the CB case required two layers of plywood. As such the inner layer of my CB case is notched to hold the pivot and the outer layer results in a "smooth" outer surface. However, I substituted cherry for the outer layer.

    Your boat's going to be beautiful.

    Gary

  3. #353
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    Default Re: An Ilur in Vermont

    Thank you, Gary. Doubling the case wall like that would make for an extremely strong case. Do you have pictures of your CB case? It would be interesting to see how Vivier designed the supporting structures for the heavier board.

  4. #354
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    Default Re: An Ilur in Vermont

    John, When it comes time to glue-up your birdsmouth mast, give me a yell if you need help. I imagine that'll be a lot of sticky pieces of wood flopping around all at once.
    I was born on a wooden boat that I built myself.

  5. #355
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    Default Re: An Ilur in Vermont

    Thanks, Rich, I would definitely enjoy the help! For those readers to whom bird's mouth spar construction is old hat, the next bit of documentary will be ho hum. For those who are curious, or for whom bird's mouth spar construction seems complex, fear not and read on. There is an excellent article in WB #149 about the process. It basically involves planing a board to thickness, ripping eight staves from the plank, and cutting a 90 degree bird's mouth into one edge of each stave. The staves then self align when popped into an eight sided spar, which is then easily 16 sided, then sanded round.

    To start, my basement workshop is a small and crowded space. In feed and out feed of the twelve foot plank didn't take ingenuity, but it does require an open window:
    http://
    The thickness of the plank is determined by multiplying the spars greatest diameter by .4 . For my 2 and 3/8 inch diameter yard, that works out to .95 inches, a fat 15/16th of an inch. The wall thickness will depend on wood species, generally 20 percent of the spar diameter. A plain sawn plank:
    http://
    Yields vertical grain staves when ripped:
    http://

  6. #356
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    Default Re: An Ilur in Vermont

    http://

    Many passes on the tablesaw will give you a set of staves, bird's mouths ready for assembly and glue up.

  7. #357
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    Default Re: An Ilur in Vermont

    http://
    This was a practice piece I did a year or so ago.....

    http://
    From eight to sixteen sides is easy-peasy.

  8. #358
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    Default Re: An Ilur in Vermont

    Sorry John. I looked and couldn't find anything illustrative regarding the setup of the CB case.

    Carry on.

    Gary

  9. #359
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    Default Re: An Ilur in Vermont

    Carrying on, then, the staves need to be tapered.....I saved the strongback upon which the hull was built. It makes a nice, long, flat assembly bench for just such an occasion:
    http://

    As the next picture illustrates, the staves need to be held straight for accuracy in lining off the tapers.
    http://
    I screwed a long, straight batten to the bench, to which I clamp the staves so that tapers can be marked:
    http://

  10. #360
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    Default Re: An Ilur in Vermont

    Next, the tapers are rough cut on the band saw. In this picture, I am halfway along the long taper of a stave, sneaking up to the outside of the pencil mark I used in marking off the taper:
    http://
    Once the tapers were rough cut on the bandsaw, I used a plane to smooth down to the line on staves one and eight, then sandwiched the rest between, and used the finished outside pair as guides to bring the rest to final dimension together:
    http://

  11. #361
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    Default Re: An Ilur in Vermont

    http://
    All tapers cohabiting happily. From here, popping the bits together to test the fit brought satisfying results:
    http://
    http://
    Ready for glue up. I know this technique is very well trodden ground, but posted pics hoping that they will be a useful future reference for folks treading it for the first time.

  12. #362
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    Default Re: An Ilur in Vermont

    John, You move right along! I've been wasting too much time splitting and stacking firewood. I've got to get back in my work shop!
    I was born on a wooden boat that I built myself.

  13. #363
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    Default Re: An Ilur in Vermont

    I just spent a pleasant afternoon over at John's place helping him glue up his spar and generally chatting about boats. He knew that Oughtred's Tammie Norrie was a close second in my design selection before I selected Eric Hvalsoe's HV13 as my present build. He had a set of plans for this boat and loaned them to me today just so I could take a look.
    So, I return home with these plans tucked under my arm and my wife gives me a look of horror, as in, "You're not really going to build ANOTHER boat, are you?" For some strange reason, she feels that having six boats is enough. I assured her that they were just for looking, not building. I think she believes me, but to be on the safe side, I hid them in my workshop so they wouldn't "accidently" end up in the woodstove.

    But, who knows, in a couple of years, it would be a nice little boat to build....
    I was born on a wooden boat that I built myself.

  14. #364
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    Default Re: An Ilur in Vermont

    And thank you very much for the good help and good company, Rich--it was an easy job for two pairs of hands, but would have been difficult and probably pretty messy to tackle solo. I just checked the spar, and the epoxy had cured enough for me to loosen all those hose clamps to have a peek. They all came off without a problem, none of the squeeze out glued the clamps to the yard. I may get around to trying to cobble together a spar lathe, but for this first one, I'll likely sand by hand after sixteen siding tomorrow. This evening, I put together this, after recalling a similar widget Jim Luton made when he was doing the spars for his Matinicus double ender:
    http://

  15. #365
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    Default Re: An Ilur in Vermont

    Nice write-up of the process, John. Looks like the building form is close to an ideal fixture for such a task. Very prescient of you not to hack it up after we turned the boat.

    Dave
    Sooty Tern Build Thread: Another Tern in the Works!
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  16. #366
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    Default Re: An Ilur in Vermont

    [QUOTE=Clinton B Chase;3929393]I love to sand...I think it's the most wonderful, zen-like, productive thing to do in the world. Honestly....just sayin'. I think I love everystage of a boat project because there is almost always a totally different type of phase to look forward to next. /QUOTE]

    Yes........I went into the garage this morning after chores, on a gray, rainy, soft morning. Looked up and it is a brilliant, sunny noon. Where did the morning go? Sixteen siding:
    http://

    And getting toward round:
    http://

  17. #367
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    Default Re: An Ilur in Vermont

    Wow John, you're making great progress! That Euro-larch looks like nice stuff, I've had some experience with the domestic N.A. variety (Larix laricina), and while it is a very useful wood, it has some shortcomings as well. First off, I don't see any sap pockets in the pictures of your wood, the hackmatack that I've used was full of them. Also, yours seems to have nice even grain, the stuff I've used was pretty coarse, and it tore out badly when machined.

    As a help to any here who would like to learn how to readily identify European larch (Larix decidua), I am posting this helpful video:


    Tom

  18. #368
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    Default Re: An Ilur in Vermont

    Hi John,

    Thanks for replying re the Lug Yawl rig a little while back. I've been giving this some more thought and I'm just wondering if the rig has also been designed so that you could step the main in the Lug Sloop mast foot and sail without the mizzen, as an alternative?

    Cheers,

    Adrian

  19. #369
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    Default Re: An Ilur in Vermont

    Adrian, I don' see why you couldn't do that. The plan set has very clear detailing about the mast step and partner arrangements so that the lug sloop can be sailed as a balanced lug. Seems like it would be easy to set up that way. The boat could be sailed in either the lug yawl or the "bourcet-malet" configuration, but there would be some choices in set up while you were on the beach--the down haul arrangements would need different attachment points depending on the rig, and if the main were boomless, the sheeting arrangements would need some thought as well. Also, if the forward deck was built to accomodate both set ups, you would have to lift the mast and set it down through a hole in the deck in order to step the mast as a lug yawl--not a big deal if the mast is light, but maybe a bit awkward if you are trying to raise or lower the mast on the water in a boat pitching or rolling in swell. It would probably be set up without strong intent at going back and forth from sail to row on the water, if you set it up as the bourcet-malet, but having the step and mast partner arrangements built in would give you many choices of set up, and great flexibility. Hope that helps.

  20. #370
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    Default Re: An Ilur in Vermont

    Hi John,
    I am probably being dumb here, but you have lost me when you say the boat could be sailed in the bourcet-malet configuration, I thought that this was a 3 sail rig (as per the Ebihen 16) with main, jib and mizzen? I was thinking that the Lug Yawl rig as designed for you by Francois would probably use the missainer front mast step with the mizzen and was wondering whether if you dispensed with the mizzen, it would be possible to sail with just the main, but stepped back in the lug sloop mast step to maintain the sail balance. Are we talking about the same thing?

    Cheers,

    Adrian

  21. #371
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    Default Re: An Ilur in Vermont

    Adrian, I think we are mostly on the same page......I commissioned FV to design a pure lug yawl, because I am planning to use the boat for camp cruising, and expect to need the ability to easily change back and forth from sail to rowing. He drew me the plan that I posted as a drawing some posts back, without any discussion of how it would affect the bowsprit and jib set up. I think you could probably do what you are describing, but would have Francois calculate the center of effort/center of lateral resistance to be certain. It would be really nifty to be able to sail under jib and mizzen alone, with a wide open cockpit, and it would also be nice to have the simplicity of the misainer alone when you wanted fewer strings to pull.

  22. #372
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    Default Re: An Ilur in Vermont

    A few liesurely hours with Jim Luton's sanding widget has yielded a nice, smooth spar. So, without further ado, I offer you:http://

    The Larch.

  23. #373
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    Default Re: An Ilur in Vermont

    And Now:

  24. #374
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    Default Re: An Ilur in Vermont

    The Spar Bending Test:
    http://

    This is well described on Stuart Hopkin's web site for Dabbler sails. The weight for the yard is suspended from the halyard attachment point. Measurements are taken at 1/4, 1/2, and 3/4 of the length of the spar, noted by some bits of masking tape. Measurements are taken from a string, to the nearest 1/8th inch. The weight is 1/3rd of the sail area the spar will carry, in this case 40# for the 118 sq foot main.

  25. #375
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    Default Re: An Ilur in Vermont

    Many thanks John, I will check this with Francois.

    Cheers,

    Adrian

  26. #376
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    Default Re: An Ilur in Vermont

    Quote Originally Posted by John hartmann View Post
    It would be really nifty to be able to sail under jib and mizzen alone, with a wide open cockpit.
    That was what I enjoyed about my Drascombe Lugger the most, I sailed her "jib and jigger" whenever conditions allowed. The Missus especially liked the boat when there was no mainsail set, with no boom it was a nice place to lounge around.

  27. #377
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    Default Re: An Ilur in Vermont

    The larch seems to make a pretty stiff spar. What's the max bend, about 1/2"? That shouldn't give the sailmaker any trouble at all. I wonder if the birdsmouth construction makes for a stiffer spar then if it were a solid stick? I would think so.
    I was born on a wooden boat that I built myself.

  28. #378
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    Default Re: An Ilur in Vermont

    Yes, Rich, it is a stiff spar--offsets from butt to tip were 1/8, 3/8, and 1/4 inch. Max diameter is 2&3/8 inch, and the spar weighs 8 pounds, 12 oz.The mizzen mast will be 2 inches in diameter,and the bending test will only require 8 lbs, so the bend should be negligible.

  29. #379
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    Default Re: An Ilur in Vermont

    Rich, no the Birdsmouth won't make it stiffer. Stiffness or deflection = Load x Span ^3 divided by 4 x Youngs Modulus x width of beam x depth of beam ^3. (edited: this is a generalized formula for a typ. beam rectangular or square in section. For one that may better represent deflection in a mast...a cantilevered beam...a better formula is posted below in #380, thanks Dave).

    In other words, with simple beam theory in mind, Deflection is an inverse function of the diameter of the spar to the third power. So it's the diameter that counts in spar stiffness, whether hollow or not. Strength is a different manner. The lug mast should be as stiff as possible without making it too heavy. His deflection looks good...i.e., not much!

    I like my yard to have a bend in the upper portion to help depower the sail.
    Last edited by Clinton B Chase; 11-22-2013 at 08:58 AM. Reason: clarified formula
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  30. #380
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    Default Re: An Ilur in Vermont

    The engineer in me needs to be a little bit pedantic here.

    The formula that Clint posted is technically for a beam with a solid rectangular section. For general shapes cantilevered and loaded at the end, the formula is:

    FL^3/(3EI): F=load, L=span, E=Young's Modulus, and I=Area Moment of Inertia.

    The Area Moment of Inertia "rewards" having material farther from the beam centerline. Thus, Clint is generally correct that beam stiffness is governed primarily by the outer dimension -but it's not correct to say that the hollowness doesn't have an effect.

    For two beams of the same outer dimensions, material, grain orientation (for ansiotropic materials like wood) - one hollow, one solid - the solid one will be stiffer than the hollow one. However, for the same *amount of material* (ie weight), you can make a stiffer hollow beam than solid beam by moving material from the center of the beam to the outside (i.e. making a larger diameter) - and it's a strong effect.

    There's an additional consideration that comes into play with birdsmouth construction in wood because using birdsmouth construction you have more flexibility in how you orient the grain than you do in just getting a spar out of monolithic slab of wood.

    Dave
    Sooty Tern Build Thread: Another Tern in the Works!
    Sooty Tern Blog: http://xflow7.wordpress.com

  31. #381
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    Default Re: An Ilur in Vermont

    Quote Originally Posted by xflow7 View Post
    The engineer in me needs to be a little bit pedantic here.

    The formula that Clint posted is technically for a beam with a solid rectangular section. For general shapes cantilevered and loaded at the end, the formula is:

    FL^3/(3EI): F=load, L=span, E=Young's Modulus, and I=Area Moment of Inertia.

    The Area Moment of Inertia "rewards" having material farther from the beam centerline. Thus, Clint is generally correct that beam stiffness is governed primarily by the outer dimension -but it's not correct to say that the hollowness doesn't have an effect.

    For two beams of the same outer dimensions, material, grain orientation (for ansiotropic materials like wood) - one hollow, one solid - the solid one will be stiffer than the hollow one. However, for the same *amount of material* (ie weight), you can make a stiffer hollow beam than solid beam by moving material from the center of the beam to the outside (i.e. making a larger diameter) - and it's a strong effect.

    There's an additional consideration that comes into play with birdsmouth construction in wood because using birdsmouth construction you have more flexibility in how you orient the grain than you do in just getting a spar out of monolithic slab of wood.

    Dave
    Thank God for engineers, but just looking at that formula makes my head hurt! I guess this is why I build 'em, but don't design 'em.
    I was born on a wooden boat that I built myself.

  32. #382
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    Default Re: An Ilur in Vermont

    Well, at least I spared you the integral expression for moment of inertia.

    In all seriousness, though, I always hesitate to make posts like that. While I'm a good engineer, and there are many engineering-y topics that I know pretty well, I would never claim that that makes me an expert on boat designs, or that such arcane formulas are the be-all end-all of good design.

    What Clint posted was entirely reasonable for the current purposes. I just think it is important to make sure that when formulas are brought up, they are understood for what they are.

    As far as building and woodworking, you'll all soon be seeing all the ways I can screw that up over the next year or two!

    Dave
    Sooty Tern Build Thread: Another Tern in the Works!
    Sooty Tern Blog: http://xflow7.wordpress.com

  33. #383
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    Default Re: An Ilur in Vermont

    Dave and Clint, thanks for that explanation. I wish my college physics professors had been so clear! Clint, can you speak a little more to having the top portion of a yard flexible to depower a sail in gusts? Is that a trial and error process, or can you figure how much bend to build into a stick? It would seemto me to be a trade-off.... on one hand, you would have a built in safety valve for gusty conditions, on the other, wouldn't a more flexible spar make it harder to flatten a sail to depower it as winds increased?

  34. #384
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    Default Re: An Ilur in Vermont

    John, in fact a bendy spar does depower as the leach opens up in a puff, and the middle of the sail stays pretty much the same.

    Fractional racing sloops do the same thing with bendy masts.

    Allan
    And the Binnacle-bats wore water-proof hats
    As they danced in the sounding sea.

  35. #385
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    Default Re: An Ilur in Vermont

    Dave, thanks! That formula is much more consistent with my experience. I have definitely found that removing material from the center had somewhat an effect on stiffness of the resultant spar. I'm going to send you a PM just to further my own understanding and not bog down this thread. Cheers,

    Quote Originally Posted by xflow7 View Post
    The engineer in me needs to be a little bit pedantic here.

    The formula that Clint posted is technically for a beam with a solid rectangular section. For general shapes cantilevered and loaded at the end, the formula is:

    FL^3/(3EI): F=load, L=span, E=Young's Modulus, and I=Area Moment of Inertia.

    The Area Moment of Inertia "rewards" having material farther from the beam centerline. Thus, Clint is generally correct that beam stiffness is governed primarily by the outer dimension -but it's not correct to say that the hollowness doesn't have an effect.

    For two beams of the same outer dimensions, material, grain orientation (for ansiotropic materials like wood) - one hollow, one solid - the solid one will be stiffer than the hollow one. However, for the same *amount of material* (ie weight), you can make a stiffer hollow beam than solid beam by moving material from the center of the beam to the outside (i.e. making a larger diameter) - and it's a strong effect.

    There's an additional consideration that comes into play with birdsmouth construction in wood because using birdsmouth construction you have more flexibility in how you orient the grain than you do in just getting a spar out of monolithic slab of wood.

    Dave
    Clinton B. Chase
    Portland, Maine

    http://tinyurl.com/myboats

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