CNC Plans not Included

Discussion in 'Multihulls' started by jorgepease, Sep 19, 2016.

  1. brian eiland
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    brian eiland Senior Member

    On Maltese Falcon the sails furl into a slot in the mast. The yards (crossbeams as you called them) are their to guide the upper and lower edges of the sails out to the extreme ends of the yards.

    One of the problems that MF had to solve was how the slot that contained the roller up sails weaken the free standing mast tube.

    MF was also a rather complicated system that facilitate by the overall size of the vessel and its rig(s).

    I was hoping to find some simplification for a smaller vessel's application of the basic Dynarig concept. One of those simplifications involved the reefing to the rig. I (we) in that square rig discussion were looking at reefing the rig in a more conventional manner such as raising and lowering the sail area via a 'up-down manner' , rather than horizontal furling the individual sails as in the MF.
    In that vain we sought to have the 'yards' (those crossbeams) slide up and down the mast tube. That model vessel on the video sought to make those yards look like flat plates that would act as 'aerodynamic fences' between the yards up and down the overall sail shape, and they would stack flat as the rig is reefed.
     
  2. jorgepease
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    jorgepease Senior Member

    That idea of yards up and down the mast reminds me a bit of the omer wing sail.

    I think it's pretty amazing that the last tiny section accounted for most of the tipping force.
     
  3. jorgepease
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    jorgepease Senior Member

    a cool post on free standing masts, wanted to keep it because his, designed by sponberg, was elliptical, not round. Here is what he says oh and I am of the same mind about wind noise through stays, hate that stuff.

    Hi. Long time listener first time caller

    In 98 we replaced our ageing stayed rig with a prepreg carbon free standing mast on our equally ageing Spencer 42. A big sister to Hal Roths original “Whisper”

    I wrote an article detailing the whole event for Ocean Navigator magazine which was published in the May/June 1999 issue #98.

    Since we built the mast our selves from scratch including the work on the deck and hull most of our costs were materials. When the dust settled our cost for everything from the deck up with new sails came to about five grand less than the cost for a CT 37 project which was happening at the same time here in Vancouver. The 37 was cutter rigged, double spreaders with all new hardware, rigging, mast and sails. All professionally done.
    If we had hired out the work it would have been beyond our budget by a wide margin.


    The gentleman we hired to design the mast, its section, lam schedule and new sail plan was Eric Sponberg a yacht designer and certified engineerworking out of Newport Ri. at the time but now based in Florida. He has a lot of experience with free standing rigs as well as carbon and was a key asset to the whole project. His contribution was worth every penny and more!

    A free standing mast like its stayed brethren has its advantages and disadvantages. Having sailed all my life in stayed rigs and the past 9 or 10 with a proper free standing rig I probably would steer clear of stayed rigs on my own boats if at all possible, but, hey, never say never!

    The primary disadvantage is up front cost and from my point of view it is probably the only disadvantage.
    Most people are familiar with the freedom rigs. In order to keep labour and materials costs down to a reasonable number they were built on what were essentially aluminium flagpole mandrels.
    This geometry is one of the worst shapes one can have on a free standing mast. The bending characteristics are way out whack for designing a sail with decent shape. It can be done of course. Building to a price they really had no choice.
    It is to the sail making industries credit that the damn things can sail at all. My suspicion is that the geometry of these kind of masts do nothing to help the sail maker confronted with building a sail for these things.

    Eric’s design called for a elliptical shape with a modified entasis shape (think the top half of a Greek column). A series of changing tapers. Not a singletaper like a cone or flagpole). As a result the old bucket goes upwind as well if not better than most boats its size.
    The new mast is about 9 or 10 feet taller than the old one. which means the rig is about 60 to 80 pounds heavier than the old deck stepped rig all up. The Centre of gravity is almost 3 feet lower than the old rig so they kinda cancel each other out.
    If we were to do it again both Eric and I feel we could shave another 60 to 100 pounds off the final weight.
    The work on the hull and deck was considerable and took us about three weeks full time to complete Suffice to say that there is a lot of carbon, Knytex and glass where there wasn’t before. All told we used almost 20 gallons (finished/mixed) of epoxy nicely squeezed out I might add, to complete the hull/deck modifications.
    We had a lot of fun doing this project, met a lot of cool people, and are still having a ball sailing the old bucket.
    We sail a lot and have put the rig and boat through many miles of sailing in a wide variety of conditions. Not one single creak or groan from the rig. The spartite occasionally squeaks a bit and the mast and halyards hum going upwind in a blow with too much sail up. That’s about it.
    One thing we didn’t anticipate was how quiet the rig is in high winds ( to date 58 knots true). No screeching and howling in the rigging. Because of the relative quiet we tend to make less hurried and more relaxed decisions. That alone was worth the price of admission.
    Handling the boat is much easier than the old rig since we can get her to go with just the main up. Tacking and gybing is a snap in close quarters. Mind you in light airs, 3 to 4 knots true we sometimes have to “snap” the big roachy full batten main over to the opposite side.
    Depending on the situation often the first reef is to furl up the jib. It’s great because you don’t have to put down your coffee to tack.
    We find we are reefing at around the the same wind strengths as before. We also find that we rarely use the traveller anymore, it is mostly the mainsheet and vang. With a bit of outhaul and cunningham.

    We still get jokers coming up and telling us that it won’t work and will fall down. Its always fun to see the variety of shapes and sizes experts come in. Its also fun planting these same jokers when we cross tacks with them out there.
    Most people are genuinely interested though and if we have a moment we love taking them sailing.
    Not a project I would recommend on a whim. We were just so damn curious, to not do it would have driven us nuts.. Nowadays I just get tired thinking about the whole thing.
    So, yes Virginia some kook actually did this and survived.
    Hope this adds something to the mix and answers a few questions.
    One other disadvantage to this rig is any knowledge I had regarding stayed rigs has atrophied, badly!

    Cheers,
    Bryan
    ________

    and this post on biplane rigs
    Flight Risk served a breif stint as a test platform for a biplane rig when the previous owner wanted to test the concept in advance of designing a 60' cruising cat. Upwind powered both sails well, broad reaching was fine, dead downwind allowed the sails to be deployed outboard on opposing sides of the boat, leaving the tramp area amazingly open. On a beam reach, and maybe 20 degrees above and below, the windward rig did indeed shadow the leeward sail, which just fell gently inboard and sat there quietly. As a beam reach is a fairly fast point of sail for a catamaran, losing the power of 1 rig was not real annoying, the boat maintained about the same speed as going upwind. The owners conclusion was that the biplane rig, with no headsails, was really a fine solution for shorthanded sail handling aboard a big cruiser. No headsails to mess with, quite easy to reef the leeward sail while on a beam reach. If each sail had 2 reef points there were 5 configurations of decreasing sail area. When I bought the boat I returned it to its original sloop rig, with assym spin and roller furling screacher, significantly more sail area, complexity, and the ability to fly a hull, which I love to do. I'm not sure if that particular rush could be produced with a biplane rig. But it could be fairly high performance if designed as such, with headsails and sufficient sail area overall.


    Dave

    And one with backstays only
    http://www.wyliedesigngroup.com/press_files/OceanPlanet, Wooden Boat.pdf


    Another with foresail
    I am a big fan of freestanding masts; auto-depowering, reliability, clean decks, lower cg than a stayed rig, less areodynamic drag, ability to sail deeper offwind without distorted mainsail shape from rigging, larger roach more efficeint mainsail shape, narrower sheeting angle for jib due to lack of rigging, no compression loads on hull and deck. I just finished a custom catamaran with one, which is a bit more challenging due to the increased righting moment. www.hytechmarine.com
    Fastwater 52.

    or - Rig developments - Ocean Navigator - January/February 2003 http://www.oceannavigator.com/January-February-2003/Rig-developments/


     
    Last edited: Jun 5, 2017
  4. jorgepease
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    jorgepease Senior Member

    Added the daggers and rudders for look, they aren't to scale as I don't know what the scale should be but they are close and fit. Daggers are just aft of the mast.

    Not giving up on unstayed masts yet. Lot's of info out there on this and I have to decide between pure performance or so many other benefits such as a smaller main mast beam which would let me have direct access to front of boat.

    My roof is now shaped in the most streamlined shape to reduce drag as per the graphic above.
    RNDR23.jpg


    If you go fast enough you don't need a galley or cabins ))
     
    Last edited: Jun 1, 2017
  5. jorgepease
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    jorgepease Senior Member

  6. jorgepease
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    jorgepease Senior Member

    It's not just about the boat being lightweight, what are you going to do about all your scuba tanks and compressor, that's heavy stuff. Well soon we will have the option to use SCORKL - Breathe underwater with TOTAL freedom http://www.scorkl.com/ :) ... up to 10 minutes at a time, perfect for setting and pulling anchors, checking out underside of boat or spearing a lobster.
    scorkle.jpg scorkle2.jpg
     
  7. jorgepease
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    jorgepease Senior Member

    The more I think about it, I don't want a pod hanging off my hull. I would want to build a something like a keel to help protect it but I start to wonder if it's worth it for a boat that rarely intends to motor. Torqeedo outboards have shafts of to ~ 63 inches. Add a portabracket and I have about 21 inches of vertical movement, that is all I need to bury the prop when needed yet have it free of the water the rest of the time. Yep minds made up, going with outboards
    ob.jpg pod.jpg
     
  8. groper
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    groper Senior Member

    Im not sure what happened with torqueedo but ive read many complaints about them. One cruising cat here had them and after many reliability issues they eventually ditched them and went back to gas outboards...

    As for you scuba equiment - you can already buy a battery powered hookah system for 1 or 2 divers. Lasts 45mins and can good for a depth of 40feet.

    PowerSnorkel | Powerdive http://www.powerdive.com/product/powersnorkel

    Theres another one on kickstarter at the moment with a lithium battery and much lighter and cheaper also here;

    AirBuddy is small and light, battery powered hookah diving gear. http://www.airbuddy.net/features.html
     
  9. jorgepease
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    jorgepease Senior Member

    Torqeedo is also expensive but quite a few others out there now. It doesn't have to be torqeedo and can be a pod drive that I modify to a retractable bracket. Ran into an Italian guy today who has been living on a 40 foot cat for the last 20 years. I asked him about electric drives, and he said he used to have one with a generator, then he went to solar panels and batteries no generator, then he went to no motor at all and he says he likes that best. lol :) ... but to be fair, this guy doesn't have a schedule, know what time it is or probably even what day. He always anchors, rarely goes to marinas or is seen on land lol, I would never have met him except he was socializing with old friends who I happen to know.

    Those hookahs are probably my speed as I can't hold my breath for that long. Free divers will love the one I posted, they can stretch 10 min to 30 easy.
    I understand how they feel, I used to have a gas powered hookah and the hose was a pain. For $200 I will buy a few )) and probably end up with the electric hookah in the end ))
     
  10. jorgepease
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    jorgepease Senior Member

    Almost all weight is in the center of my design. The outboards, or pods on extensions, are just aft of the main mast beam. Here I draw them with a portabracket which gives you 24" of vertical movement. The batteries are inside the hulls no more than a few feet away. In the up position the pod isn't very high above the water, an outboard would give the advantage of having the builtin tilt. There is easy access to the hydraulic bracket from above and to the pod from below, no need to yank the boat if the pod goes bad.

    RNDR22.jpg RNDR23.jpg RNDR24.jpg RNDR25.jpg RNDR26.jpg
     
  11. groper
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    groper Senior Member

    If you are to have them hanging like that there will have to be zero play in the mechanism (hard to acheive in practice) or it will flog back and forth in a seaway when waves strike it. Constant flogging will make annoying noises and eventually destroy it in the long term. It really should come up much higher if it is to be stowed.
     
  12. jorgepease
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    jorgepease Senior Member

    Yes, that is the argument to also have a tilting mechanism, probably worth getting an outboard it might be nice to rig a tilting mechanism on the pod because then motor noise would be non existent.

    Just saw the teaser for my nephews environmental snowboarding/mountaineering documentary for the Krgyzstan segment (being shot in 6 countries, one country to go) it's pretty impressive quality. He is going to have shoot my Living Off The Grid in a Luxury Catamaran Documentary )))) damn kid isn't even out of college yet!!!

     
  13. jorgepease
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    jorgepease Senior Member

    Im going to lay out the steering for the interior helm. From what I read the transmission steering is good for when the helm is a long distance from the rudders. I plan to use a kick up rudder system similar to shuttleworths where the rudder kicks up between the transom steps unless I can find a better way. I can't figure out how the steering would hook up, only maybe if I terminate in a hub and switch to a flexible chain or belt. How is this normally done?
    cat-trans-1.png Kick-upRudderSystemweb.jpg PortTransomweb.jpg TransomDetailweb.jpg
    Thinking on how an outboard motor works, it can be raised, tilted etc without losing steering
    9.5 Swivel Bracket.jpg
     
    Last edited: Jun 8, 2017
  14. groper
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    groper Senior Member

    The way i normally see it here is the rudder shaft is mounted into a box which sits fair in hull. The tiller head on the top of the shaft is connected to hydraulic steering ram which has flexible hoses to it and the ram is also mounted on the pivoting box. So the whole lot kicks up and the flexible hoses allow the little bit of movement for changing geometry.
     

  15. jorgepease
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    jorgepease Senior Member

    I'd like to provide the tiller option but also want the inside helm to have a good feel. The Jefa transmission steering systems look pretty robust, easy to install and is supposed to give you a nice feel, I don't want to ruin it in the last few feet with hydraulic but maybe a cable system at the end. First I want to see how the rudders will work on this boat.

    I had to shrink the galley a bit more, got rid of the barstools, I will put a nice helm chair instead, just leave that side of the room to navigation and controls etc... boat is getting lighter by the day ))

    RNDR24.jpg RNDR25.jpg RNDR26.jpg RNDR27.jpg
     
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