Free standing mast

Discussion in 'Sailboats' started by Paul A, Apr 28, 2010.

  1. Fanie
    Joined: Oct 2007
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    Fanie Fanie

    Aye Paul A, you do come over a bit agressive.

    Just because someone doesn't suggest what you want to hear, doesn't mean they have it wrong. Let's take it one step at a time and respect each other's views, there is always some another knows you don't. Stepped into it myself a couple of times.
     
  2. Paul A
    Joined: Apr 2010
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    Paul A Junior Member

    How much of an apologetic qualifier do your tender souls need? My insistence that I wasn't attempting to insult wasn't enough?

    Offering speculation and conjecture to an engineer (which was what was done with the inaccurate history of sharpies, etc.), is about as useful as **** on a lamp post, nearly as insulting as cursing at them, particularly if placed in a supposedly informative format such as this.

    So, what is this, a boat design and engineering discussion forum or inaccurate historical recollection, speculation and conjecture about stuff you don't understand forum?

    Now, another qualifier, not all have been this way, with a few actually trying to mediate, which is much appreciated, but beam calculations is an engineer's common task. If it's beyond a poster's abilities, which is understandable, what is all this talk about carbon, when I want wood, cat ketch sharpies when I was talking about a modern masthead sloops and why shouldn't I be insulted at the preference for a established forum member and the indifference to a new comer? Either you can offer a set of scantling guidelines, possibly direct me to some or not. This isn't what happened from some of the posters, who made up history and suggested my request it wasn't usual, when obviously free standing wooden rigs have been around for centuries.

    Suggesting an argument "is weak" isn't a punch in the nose, but simply a statement in reply to a post, that didn't offer any support for itself, particularly in light of obvious flaws in that argument.
     
  3. Gary Baigent
    Joined: Jul 2005
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    Gary Baigent Senior Member

    Paul,you could consider a small chord wing mast, (that also rotates) which would still be considerably larger in chord and thickness than your original mast measurement suggestions, and therefore quite capable of handling all the loads your boat and the wind could dish out and still remain vertical. Your yacht is not a heavy dunger and will accelerate away from gusts. It could be built in 8mm strip planked white cedar or paulownia with a tapering box internal section central in the canterlevered areas from mast base to 30% up the mast. This mast would not only be lighter than your original, it would also be far more efficient in terms of power and reduced drag .... and wing masts, no matter what they say, are not difficult to build. Something like one of these.
    ps: agreed, the kumbaya stuff can go too far.
     

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  4. troy2000
    Joined: Nov 2009
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    troy2000 Senior Member

    Well, I guess I wasn't done after all.
    You asked for opinions, and you got some. The gracious thing to do would have been to thank everyone nicely, and pursue the replies you considered useful.
    No, it wasn't enough. Adding disclaimers to insulting remarks doesn't change their nature.

    You weren't offered any inaccurate history concerning sharpies. Everything I said can be backed up by referring to Howard Chapelle and other authorities.

    This is a boat design forum. Many of our members are experienced professionals, and the best way to get their help isn't by being rude and condescending to them or the other members.

    It takes a certain amount of chutzpah to come barging into the middle of a group of people who know each other, get rude and obnoxious, then complain that they like each other better than they do you. What did you expect? If you want unconditional love, go get a puppy. If you want respect from people, treat them respectfully.

    Getting back to your original request ("...would be interested in hearing what you all think"): if you wanted calculations or scantling guides instead of opinions, perhaps you should have asked for calculations or scantling guides to begin with, instead of just asking people what they think.
     

  5. sharpii2
    Joined: May 2004
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    sharpii2 Senior Member

    No insult taken.

    Sailboats present unique design problems, especieally when it comes to rig design. This is especially true when it comes to ballasted monohulls. The rig must be strong enough to heel the boat all the way over without breaking, but light enough to not raise the combined center of gravity of the boat too high.

    If the mast is too heavy, the boat will not recover from a capsize, or if the mast is too overweight, even a a knock down. With a jibless rig this is much easier to do with more ordinary materials. This is because any reasonable bending reaction of the mast is not going to effect the sail shape too much. In some cases, the bending of the mast can be exploited to flatten the sail in heavier winds.

    With a large working jib, you have a totally different animal. The luff of the jib most be kept at least reasonably straight. This takes a much greater amount of stiffness than holding the luff of a plain jibless sail sufficiently tight, even if the luff of such a sail extends past the mast, as with a balanced lug or chinese lug.

    So the substitute materials must compete with carbon fiber in stiffness to weight ratio, not just stiffness, if you want a large working jib. And the mast must not be too bulky, as bulkiness effects windward performance.

    This does not necessarily apply to light air jibs, as these are generally taken down before the luff sags enough to make them useless. So you may see a boat with a non carbon fiber mast sporting a huge asymetrical spimnaker in a zepher and even sailing to windward. This is because the force of the wind increases by the square of its velocity. A three knot breeze has one quarter of the force of a six knot one.
     
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