efficient 10m displacement powercat (build thread)

Discussion in 'Boatbuilding' started by groper, Apr 15, 2012.

  1. groper
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    groper Senior Member

    The post is stepped upon the original I beam bulkhead. There is a lot of detail which is not visible in the pic but I had consultation with the naval architect who designed this boat and followed his recommendations which included the gussets you can see top and bottom of the post I added. There is additional decoring of the foam sandwich roof and subsequent addition of laminate surrounding the area, same goes for the bottom of the post. Below this, not visible, there is additional longitudinal web and vertical solid timber blocks between the transverse and longitudinal web. There is a heavy uni directional flange top and bottom of the transverse bulkhead you can see, which forms the majority of the stiffness required for the mast compression load of about 6 tons design limit.
     
  2. Ad Hoc
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    Ad Hoc Naval Architect

    Then you should be ok. As you'll get in-plane compression loads into the deck.
     
  3. groper
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    groper Senior Member

    Yeah, I guess some of your tuff love must have got through to me over the last few years adhoc, still learning but I figured that would have been the case which is why I specifically asked about it, a quick phone call and a few questions later I had all the info I needed. It's great that bob oram was happy to offer his advice over the phone when his service to this boat could have ended when it was launched by the previous owner...

    Here's the latest pic with some paint splashed around today...

    [​IMG]
     
  4. Ad Hoc
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    Ad Hoc Naval Architect

    Well, so long as it saves you heartache in the future, my work is done :p
     
  5. Barra
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    Barra Junior Member

    6 tons seems low for a 14 meter cruising catamaran? It must be very light.
     
  6. groper
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    groper Senior Member

    It's only a 12m boat. Empty it's 3.5tons, max designed displ is 4800kgs.
     
  7. DennisRB
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    DennisRB Senior Member

    This a really is great project. Well both of these are. Deserves its own thread IMO. I now eagerly await the final result of both vessels. I never did quite catch the final story of what happened with CNO and Mas. I followed it for a while before it started going loopy.
     
  8. Charly
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    Charly Senior Member

    Hey groper, it looks real nice. How is the crossarm attached to the tiller head? what is the crossarm made of?
     
  9. groper
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    groper Senior Member

    There is just a loose fitting bolt through the tiller head which acts like a pivot pin. The cross arm is just a stainless tube, with threaded ends so that the rudders can be aligned. It's all been fabricated custom, it's not off the shelf afaik. Slightly off center on the read deck, you can see the hydraulic cylinder mounted, a tag is welded onto the stainless tube and the cylinder arm bolted through the tag.

    This was all slightly modified f the original plans, the tiller heads should be below deck and the cross arm going through a slot similar to yours charley, then the hydraulic cylinder mounted under the deck rather than on top. There is also plans for a full kick up rudder system, which is why I have not modified any of this yet...
     
  10. groper
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    groper Senior Member

    The other boat, got a little taller...
    [​IMG]

    Fractional single spreader rig, inner and outer diamonds all with Dynex Dux synthetic standing rigging. 2:1 main and fractional spin halyards.
    Still have to mount the boom and run all the lines back aft inc the single line reefing. Need to mount some deck organisers and a few more clutches and blocks. Then to measure up for sails...

    Kitchen drawers are finally in fabrication so they can be fitted when they're ready before Xmas.

    Immediate stilll to do list ;
    - targa bar aft of cockpit for dingy and solar panels.
    - interior floor coverings.
    - install reinforcings for prodder to take screecher sail.
    - bit mor deck hardware and a couple more winches for downwind sheeting angles.
     
  11. Charlyipad
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    Charlyipad Senior Member

    Looks great Groper

    What size are rods for the stanchions? I was thinking of using glass rods stock glassed though the decks...with added doubler "biscuits" to give more bury, using stubs instead of full length, and then slipping the stanchions, probably stainless, over them. maybe a better aggangement would be full length glass rods? Or tubes?
     
  12. Saqa
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    Saqa Senior Member

    Get it on the water already mate, hanging to see how yours goes :D Your spaniards are gonna migrate to koro sea to mate and I will catch and eat them before you get on the water :p
     
  13. groper
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    groper Senior Member

    The solid glass rods are 1 inch diameter. They are simply glassed into the right angle area between the hull side and bulkheads. Bit of bog, press them in, coved around them, and glassed over on the inside of the boat, out onto the hull sides and onto the adjacent bulkhead. There is about 5 inches of bury underneath the deck which you have to work with... Nothing to glass on the deck, just bog around the hole they penetrate through to seal them up. Stainless is expensive, but if your going for that look then you don't have a choice, the stubs would work well for that. Don't forget the Dynex lifelines... Much lighter than stainless and no expensive hardware required to go with it...

    No shortage of spaniards yet saqa, trolled up a few more today :)
     
  14. DennisRB
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    DennisRB Senior Member

    Nice progress. Have you got any closep pics/details on the Dynex rig? Are the shrouds Dynex too?

    How is it terminated?
    How do you tension it?
    How do you prevent chafe?
    Protection from UV?

    I need to re rig my boat and am interested in dynex rig too. But I only thought the shrouds could be done, due to numerous chafe points in the diamonds.
     

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  15. groper
    Joined: Jun 2011
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    groper Senior Member

    Sorry I don't have anymore pics right now, I'll get some more soon. Everything is Dynex Dux save the forestay because of the furler foil has to spin around it... the seagull striker on the forebeam is also Dynex. Only way to do the forestay in Dynex would be to use a structural furler with torque rope, but they are very pricey. Otherwise, you could use hank on sails with soft hanks.

    The Dynex is spliced onto a stainless eyelet to terminate the ends. The eyelet is held by a normal rigging screw with the toggle pin passed through the stainless eyelet. You can also buy aluminium terminators from colligo aswell, for use with lashings or rigging screws for tensioning. There is also soft shackles used on the inner diamonds instead of eyelets. Ie . Larger diameter Dynex loops to account for the lost strength in the tight radius loop knot.

    There is no chafe prevention, it's pretty tough all by itself. You can read more about its properties on the colligo marine website, good info there. But in places where you can expect a lot of chafe from sheet ropes etc, we have a sheath over it. Same goes for UV, it's pretty resilient all by itself so most of it is naked.
     
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