Freestanding

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

  1. messabout
    Joined: Jan 2006
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    Location: Lakeland Fl USA

    messabout Senior Member

    I am a believer in free standing masts for small boats. There are several advantages unless you set a fore sail. But I am also a realist and there is no way a free standing mast, of an equivalent section modulus, can carry a larger load than a shrouded mast.

    The free standing mast is a cantilever beam. It can not compete with a partially supported beam as in a mast with partial support in four directions. Sure you can beef up the section to compensate.

    I like free standing masts for trailer boats because of simplicity and absence of all that damned wire and fiddly bits. Not only that, but you can let the sail weathervane when advantageous....like at launching or retrieving sites. You can also rotate the mast to stow the sail, or even reef. All that is dandy but do not forget that there is a huge load at the heel of the mast because the whole deal is a giant lever, and the pivot point had better be mucho strong.
     
  2. bondo
    Joined: Jul 2009
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    Location: Seattle

    bondo Junior Member

    Hey messabout. Of course the stayed mast/same section thing you say is true. Why is everybody trying to challenge my science? Work with me. What I should have said is: a freestanding rig needs to carry more sail than its counterpart. Fortunately, it can...in the way it flexes. There. Btw. I have always had a bs meter go off when I hear the square shape causes too much drag problems. It seems so obvious to someone who's had one. When we point our apparent wind is dead on the 45. Not on the side of a flat surface, but aimed directly at the "corner" of the box. Again, I'm not saying my way is better than your way. But I do call bs on the thought that a box mast creates problematic drag to the degree that you can notice it. I have to be honest...I wish there weren't such a pool of sharks looking to be the first to spot a rediculous oversight on my part. I already built the damned thing. Let me tell you about it, then you can all ravage it.
     
  3. SaugatuckWB
    Joined: Jan 2014
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    Location: Saugatuck,MI

    SaugatuckWB Junior Member

    Do you have a pic of the mast? Maybe a drawing of your proposed sail plan? Just wondering. I agree on the differences of a square or round mast, negligible or non-existent for most purposes and particularly on this boat. If you had a foil shaped mast that rotated it would be different, but not on this boat. Any pics of the sharpie? Lots of those with unstayed rigs.
     
  4. SaugatuckWB
    Joined: Jan 2014
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    Location: Saugatuck,MI

    SaugatuckWB Junior Member

    Sharks patrol these waters, sharks patrol these waters. Stay in the life boats people. That dayglow orange life preserver, it won't save you, it won't save you. Swim like a motherf....er!
     
  5. bondo
    Joined: Jul 2009
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    Location: Seattle

    bondo Junior Member

    My sharpie was way back, when there were literally only a few prints and no copies of photos. Probably put in the water in 1985. I haven't seen a picture in a few years but I'm hoping it turns up. Designed and mostly built by Christian Maas. No cabin, had a pretty mahogany coaming around both open cockpits. Me and his younger brother built the appendages and masts as I said. The first rudder was too small. You could be flying along on a reach and the rudder would get overpowered and start to cavitate. When it started to cavitate the boat would "spin out" and turn toward the wind and screech to a halt. Never tripped over but it scared the you know what out of everyone. One day it happened maybe three times so I built a bigger rudder and it stopped.

    Don't get me started on sharpies. I don't understand why sharpies aren't the most common sailboat type.
     
  6. bondo
    Joined: Jul 2009
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    bondo Junior Member

    So I guess while speaking of my sharpie i can tell you our instructions for building the masts. Scarph cvg Doug fir together. Leave it 3/4" thick. Buy cvg 4 x 4. Calculate the staves so they could be clamped around the 4x4 as a solid core for the base of the mast. That meant the masts were 5" square/solid to above the partners (except for ventilation hole) then hollow, tapering to 2" at the masthead. I remember him saying "make them as tall as they turn out (using two 16' sticks minus the scarph joint) One mast was about 6" longer for some reason so that mast went to the bow.
    Then buy two used "star class" mainsails. Cut them so they are deck mounted, rising to the boom. If it's too much area, you can cut some off, if the rudder is too small, you can build another. (He seemed to know the rudder design was small) That was it.

    Please don't presume that I think it is all that simple. But I am mentioning the specifics as a baseline. That sharpie and those masts are my baseline.
     
  7. bondo
    Joined: Jul 2009
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    bondo Junior Member

    Okay, back to it. I knew that the staves were tapered in the profile. I wondered about tapering them along their thickness. I looked and couldn't find any mention of tapering of the thickness.(I'm sure it can be found)

    A birds mouth mast would prevent me from tapering the thickness. Or at least I couldn't think of how to do it.

    I bought two finger-jointed cheap trim boards at 20' long from the local. I used cardboard butt-shims, glued to one of the sticks to plane a taper into the other. (I planned the shims so my final Sitka staves would stay full thickness until above the partners) basically, I made a tapering jig.
    I patterned the staves in the profile before tapering.
    Okay, after the four sides were cut out. Wait. One thing is you don't want your masts to be straight tapers. You need it to be a little "plump" taper. When you cut it straight such as using a chalk line the mast will look thin in the middle. I read one other guy refer to this straight line effect as looking a bit column like.
     
  8. bondo
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    bondo Junior Member

    Okay, so I was able to taper the staves thickness using my jig and the planer. I settled on 11/16" thick until above the partners, tapering to 7/16" at the masthead. I kept weighing my sticks and trying to make it lighter.

    i1341.photobucket.com/albums/o758/glenagher/c8f64098b61bb40af5a722940e7de88c_zpsb5941453.jpg

    Also, I routed a rabbet in opposite staves for gluing. I had to mount the router on my glue up table. If you haven't already stopped reading you will see that the thickness affects how the staves fit. As the staves get thinner the excess spruce gets trimmed off later by a flush router bit. This is how the staves can still fit together, even though they are getting thinner.

    i1341.photobucket.com/albums/o758/glenagher/126087235c3ffcb4493e805b60e2b8ee_zps3a58a7f7.jpg
     
  9. bondo
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    bondo Junior Member

    I bought about 80$ worth of cheap clamps from harbor freight. I built this project expecting I might have to make another.

    i1341.photobucket.com/albums/o758/glenagher/831193d9e270d35bdf54bdd69614d686_zpsade2eb25.jpg

    That brings me to the punchline. I thought about this and decided I would build to the very smallest of the sizes I thought might work. It is very difficult to resist adding safety here and extra just in case there. I know any other sane person would start bigger but I resisted. I reduced the size of this mast to only 4" solid at the partners tapering to 1 1/2" at the masthead. 22 feet long. The "bury" is deep. 42" = less leverage on the mast step. The step is bomb proof anyway. The mast only flies 18' above the partners. I know people wil want to talk righting moment.

    i1341.photobucket.com/albums/o758/glenagher/2973073cd72f67977bc68ecf245f3867_zps65a495b3.jpg
     
  10. bondo
    Joined: Jul 2009
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    Location: Seattle

    bondo Junior Member

    The main is only about 11 meters. I could get another yard on the taller mast. The shape is sort of on the sailmaker. Fully battened, but I don't know, maybe less roach. They have a formula for checking the mast bend to calculate how full to make the shape. They try to see how much flex they are working with.

    i1341.photobucket.com/albums/o758/glenagher/848bd870027d1789410ce8d5beea570a_zps0b775bd3.jpg

    Kinda hard to take a picture of a mast. 28.2 lbs before hardware.

    i1341.photobucket.com/albums/o758/glenagher/e1289dafa82cf83b003f89bc15c58916_zps0a5bc4b0.jpg

    I probably had more but I'm tired so there you go. Have at it.
     
  11. bondo
    Joined: Jul 2009
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    Location: Seattle

    bondo Junior Member

    The trailing edge is straight, for the old-school ss sail track. (another Herreshoff invention) I need to buy a masthead sheave and out haul sheave.
    Before I built this mast I thought I could build it to 25 lbs. if I build another one I would consider having the lines run internally.
    I shaped a solid stick for a boom that looked okay for awhile before I lost control of it and it didn't look right. It weighed 7 lbs. I wanted the boom to have the 7/16" roundover that the mast had to match. The solid stick boom looked odd (too much radius for the size)
    I built a hollow one that I think I love. It looks fat in the picture 2-1/4" at its widest/1-1/2" at the ends. A really light feeling 5 lbs. And strong. i think the matching 7/16" radius looks natural on it.

    i1341.photobucket.com/albums/o758/glenagher/4ecb4cdb3c97ce9cf54769852e7a1a2b_zps09367081.jpg
     
  12. Canracer
    Joined: Aug 2009
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    Location: Florida

    Canracer Senior Member

    I would think that a foil shaped mast would do better to windward.
     
  13. Canracer
    Joined: Aug 2009
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    Location: Florida

    Canracer Senior Member

    Congrats on a good looking boat. The spars look great too. I guess if you change your mind, you can always add the stays further down the road
     
  14. SaugatuckWB
    Joined: Jan 2014
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    Location: Saugatuck,MI

    SaugatuckWB Junior Member

    Spars look great. Really nice job. I'd like to see the boat when finished too. Good luck.
     

  15. bondo
    Joined: Jul 2009
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    bondo Junior Member

    I must have come across as a jerk. I really do want people to be critical now. Maybe if I say rediculous, unfounded things.
    Well...will it work? Yes. Of course it will work. At least to some degree. First I should add that I live in Seattle where winds are light in the Summer. Truth is, we need more sail area than you Florida-Texas guys.
    I've wondered about experimenting with "poly tarp" technology homemade sails. Or better, have a sail made/recut. Then, same as conventional rigged homebuilts, pull the sail up the mast and see what happens. I'm hoping it won't break off and poke my eye out but it could happen.
    If the mast seems springy right off I guess I would consider removing the extra length.
    By the way, I have had difficulty getting the weights of other rigs to compare to. Does anyone know how much their rig weighs?
    I am officially asking for criticism. Thanks if you bother.
     
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