Freestanding

Discussion in 'Wooden Boat Building and Restoration' started by bondo, Feb 10, 2015.

  1. SaugatuckWB
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    SaugatuckWB Junior Member

    Maybe your spars indicate that you know what you are doing as far as their construction is concerned and people would like to see a proposed sail plan, even if its just a sketch?

    Probably the only reason to mess with poly tarp sails would be to experiment before making or having made a real set of sails. While lots of people say they work well, they do look like hell, and since you put the effort into the spars it would kinda be a shame.

    Also, if you are talking sails as opposed to sail, then how do you propose to set a jib without a forestay, and then you no longer have an unstayed mast and might was well add a couple shrouds.
     
  2. bondo
    Joined: Jul 2009
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    bondo Junior Member

    Thanks. I would love to draw a sketch of a sailplan. I don't know how to. I have no additional idea about a sailplan other than the picture someone kindly posted earlier. I am an amateur. Most of my sailing experience is on a sailboard. The sharpie was the only big sailboat I've owned. Yes, the poly tarp thing was about experimenting. Finding the best shape for the rig.
    I do intend to fly a foresail from my mast. I tried to carry fore and aft thickness higher up to assist.
    This is how I understand it. The boat is a catboat. It is supposed to be balanced with the main alone. The retractable bow sprit extends maybe 5' forward. An asymmetrical spinnaker for downwind according to plan. The forestay isn't used for a sail attachment. The aluminum sprit seems to flex some. I don't think the setup with the sprit provides the kind of tension you are talking about.
    Something else, with my sharpie I bought a sail that I remembered as being a Buccanear 18 jib. It had a wire luff so in hindsight it sounds like a storm sail. (Wire luff) anyway, that is how you handle the issue of no forestay. I flew the jib from the rear mast. Mostly for fun. Couldn't tack with it up so it was never up for long.
    Anyway, I remember that a foresail pulling on the mast changes the sail shape of the main a little.
     
    Last edited: Feb 15, 2015
  3. messabout
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    messabout Senior Member

    Your post number 17 said; work with me. Most of us will try to do so even if we sound like naysayers.

    Here is a useful suggestion. Let us say that the mast is 250 inches long (20'10). Support the mast at two locations as in your photo. One support will be a 43 inches from the heel. That is where your pivot point on the boat will be.. The other support will be at the tip. The track side of the mast will be facing up. You'll have about 250-43= 207 inches of unsupported mast. Measure to half way 207/2= 103.5. Fill a gallon milk jug with water. Hang it from the mid mark. The mast will bend some amount and your sail maker will want to know about the bend. If he does not ask for the numbers, find a different sail maker.

    Mark off about seven or eight even spaces along the 207 inch part....207/8=25 7/8. Now stretch a stout string or wire from tip to pivot point. You will have something like a very long archers bow. Measure the distance from the mast to the wire at each location where the division marks are. Make a chart with that information. Keep the chart, it is important.

    If your sail has a 16 ft. 6 inch luff, then you will need a boom of 12 feet or more in order to get near the 11 meters of area that you have mentioned. The sail will need a fat roach and not much rise at the clew in order to get the area you are targeting. Not enough rise and craniums are in peril. If the boom is so near the deck, how do you plan to vang the boom? If you are up for using a "swing rig", the forestay tension will vang the boom. It's a goofy looking rig but it works well enough. You would not need a bowsprit with the swinger but you'd have to let the mast rotate freely.

    There is more.....If the boat is built to plan and the board is in the position as per plan, then your sail must have a center of effort pretty close to the CE of the sail on the plan. You have been a board sailor so you already know what happens when you move the sail CE forward or aft. ....Still more......If you are to use a jib, you will probably need a bowsprit. The fore sail will alter helm balance big time. Plan ahead!

    Excuse the long winded diatribe Bondo. I'm only trying to alert you to potential mistakes.
     
  4. SaugatuckWB
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    SaugatuckWB Junior Member

    Sailmaker's Apprentice: Emiliano Marino is an excellent book to help with the details of designing and making sails. Its well written and interesting enough to actually read. It gives you a good idea of how much goes into building a sail and all the factors (like CEO mentioned above) that need to be considered. If you come up with a sail plan then sailrite has a lot of materials and kits for sails. There may be an existing boat that closely matches what you want and then you could buy a kit for that boat and potentially save some work. If you are going to have someone make your sails then you are probably best giving them as much info as possible and letting them do the design work.
     
  5. bondo
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    bondo Junior Member

    Hey that's great. I'm going to do your deflection testing now and save my numbers here. I bought the sailmakers apprentice. Honestly I didn't read much of it yet. (Obviously) oh: weight in center of span = 1 us gallon/plastic container
    Spar #1, length from partners to 6" below sheave = 217-1/2". note: ( I don't know if it matters but the max deflection under its own weight is 3/8") Deflection measurements starting from partners: 1/8, (or approx 27-3/16" from partners) 1/8 =1/16"+ deflection. 2/8 from partner = 5/16"- deflection. 3/8 = 7/16" deflection. 4/8 or half way up = 1/2"+ deflection. 5/8 = 1/2"+deflection. 6/8 = 7/16"+deflection and 7/8 = 5/16"- deflection.

    i1341.photobucket.com/albums/o758/glenagher/7c01b73821611ec3f1b71f0aae3e7d46_zpsa0c8e5b0.jpg

    I don't know what this means but the whole spar balance point is 54" above partners. When comparing weights/I would get to subtract the solid "buried" cantilevered end of my spar?
    Also, some of the things you guys have said I'm not sure I even know what they mean so bear with me.

    Per plan, the mast is raked 5 degrees. I am going to plant this flag at 4 degrees. I'm moving the centers a fuzz (my mast thickness affects) and the unstayed rigs I had before seemed to get drawn back a little like a bow and arrow. You are pulling back on the rig. "Loading it up" (up haul and out haul by hand only, no winches on board) same with small spinnaker. The tightest things are going to get are hand tight. But you end up tightened back if you will. I really appreciate you guys helping me through some of these things I don't know.

    Another thought: I never had reef points on the sharpie. When I got overpowered I would sail with full foresail only. Meaning that mast was still overpowered, and now it had all of the righting moments and the loads of the entire boat to contend with.
     
  6. bondo
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    bondo Junior Member

    Wait, am I doing that right? I know I am trying to measure the chord. Of these, which of the following am I measuring? (Eg is midpoint) The total sag + 8.3 lbs = 1/2"+ or the amount of net deflection caused buy the weight which = 1/8"+?

    i1341.photobucket.com/albums/o758/glenagher/0c1e92c80181f048f65b6a3615c491b0_zps8e93a7f7.jpg
     
  7. messabout
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    messabout Senior Member

    Not sure of your exact question. I'll try to explain better than I did in my other post. If the mast was the same size and the wood was the same thickness all the way to the top, then it we could use some math to predict the deflection with reasonable accuracy. But.......you have a tapered section and it will behave differently from predictions of a simple deflection formula. We could do that with math too but the math would get pretty sticky.

    Measure the amount of deflection at several different established points along the length of the mast. You might have to use more weight to get it to bend enough to measure easily.....two jugs of water maybe. The string or wire is a temporary bow string. With the mast bent, measure in several places, along the length of the mast, between the string and the top of the mast where the track will be.

    I don't want to make a big deal of this but it does matter to your sail. Sails cost 4, 5, 6 dollars per square foot maybe even more for a one off custom sail. The fewer times it must be re-cut the better.

    Incidentally the pictures of your mast suggest high quality craftsmanship. Good for you. Seat of the pants tells me that you have built it stronger than necessary, but if the joints do not fail the mast sure as hell ain't going to fail.

    If you can let the free standing mast rotate freely, you will find a meaningful difference in the way that the sail pulls.
     
  8. bondo
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    bondo Junior Member

    Thanks for the assist. Still don't have a handle on the mast deflection test. Is test weight amount based on sq footage, anyone? Nice to hear someone say my mast looks strong enough. I thought I would hear it was too small. A rotating mast would happen if I could get a carbon stick someday. Help with rigging and fitting a sail is something I definately need. I Cut a hole in the partner today. Getting ready to start fitting the mast.

    i1341.photobucket.com/albums/o758/glenagher/93023d5d53a34f49a5b796247199850b_zpsadc93052.jpg

    I really feel better hearing a person say "hey, that mast might work" Thanks.
     
  9. Canracer
    Joined: Aug 2009
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    Canracer Senior Member

    Looks really good. What does that partner look like from inside the hull?
     
  10. bondo
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    bondo Junior Member

    I took the spar over to the boat for the first fitting.

    i1341.photobucket.com/albums/o758/glenagher/47cee61a1ba08e5efcbb346be9ee0a76_zps56ddb737.jpg

    I meant to take a picture of the inside partner details but I got distracted with the mast. This picture is before the mast is fully fitted in (still several inches high here) but you get the idea. There is a shelf in the bow that the mast passes through. The hole in the shelf acts to guide the mast into the step. I was happy how well this seemed to work. It was easy to bullseye the partner hole with the mast, same with the shelf hole. The mast heel is 1-1/2" smaller than the openings so you don't need to be really lined up. After the mast is lowered through the deck about 16" it is tip proof. The shelf will hold it. As you drop the mast farther everything automatically centers in the two holes as the mast size increases. (kinda lines up like a pen holder?)

    i1341.photobucket.com/albums/o758/glenagher/1d96fbe6e1c7b1d32907e1ccbaaf95de_zpsfd0e226a.jpg
    Whaddya think?

    i1341.photobucket.com/albums/o758/glenagher/b1b77b7a894ddfb97ccd1b71663036fd_zps35eeaac0.jpg

    Do they look right together? I want to hear if you don't like it.
     
  11. messabout
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    messabout Senior Member

    That's a saucey little boat. You have done well.
    The mast looks scary tall for such a small boat. It may work nicely if the boat is adequate to hold it's own, in spite of a significantly elevated position of its mast weight. (Polar moments and all that jazz.)

    Summer and splash time is near, go for it.
     
  12. bondo
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    bondo Junior Member

    What is polar moment? The mast drops in another 6" from the picture. How do I compare weights of rigs? My mast: bottom third weighs 15 lbs. middle third weighs 10lbs. Top third weighs 5lbs. Does anyone know the weight of conventional rigs? I have compared to wood rigs, gaff/other that were twice the weight of mine. I can't verify because freestanding rig weights aren't common. You guys have a good eye. Does my mast pass the eye test? The mast is too fat for that fat little boat? Thanks so much if you have any comments. (Thanks messabout)

    i1341.photobucket.com/albums/o758/glenagher/657ac640620262149d1d22161c01aeb5_zpsa4cdb6ce.jpg
     
  13. Canracer
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    Canracer Senior Member

    It looks fine. Honestly, I don't think that stays are unattractive. Are you planning to sail that thing this summer? You'd better get cracking. :)
     
  14. bondo
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    bondo Junior Member

    I don't have anything against stays or aluminum masts. I like the look of wooden spars. I've had a freestanding rig and I want that again. Thanks for everyone's input.

    i1341.photobucket.com/albums/o758/glenagher/1456b12223e36daab3c360f65105827c_zps368a0bbc.jpg
     

  15. messabout
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    messabout Senior Member

    Don't sweat the polar moment thing Bondo. I should not have mentioned it but my brain wheels were turning needlessly much when I typed that pair of words. Probably the Bourbon that I was sipping.

    What it amounts to is a weight or force acting on a lever. Think of yourself swinging an axe around in a whirling dervish like, circle. The head of the axe, being heavy, makes it difficult to slow or stop the rotational swing. If the axe head weight was reduced, or if the handle was shorter, it would be easier to control.

    The center of gravity of your mast is somewhere up above the center of buoyancy of the boat. The higher up, the longer the lever (axe handle). The heavier the mast, the more influential that weight and distance is. In severe cases the boat will roll and pitch more excessively than a more moderate height and weight would cause. I don't think that you will have any real problem with it.

    Keep up the good work.
     
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