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Re: [Michalak] Re: Dockbox/Harmonica

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  • James Greene
    ... I don t think you should encapsulate the wood. It s better and cheaper to use glass and epoxy on the outside to make the hull strong and waterproof, and
    Message 1 of 43 , Nov 30, 2005
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      > Well, that's good news on the epoxy and glass. I think you'll want to
      > encapsulate if you're storing it in the water.

      I don't think you should encapsulate the wood. It's better and cheaper to use glass and epoxy on the outside to make the hull strong and waterproof, and then use linseed oil/turpentine inside to repel liquid water and to make sure the wood can breathe from the inside -- so the water vapor that gets into the wood can easily get out again.

      James Greene
    • Rob Rohde-Szudy
      Still not sure what you mean. But maybe you were afraid of bending moments. While I still believe that the static forces per se can be only the max.
      Message 43 of 43 , Dec 8, 2005
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        Still not sure what you mean. But maybe you were afraid of bending
        moments. While I still believe that the static forces per se can be
        only the max. displacement of the floatation device, they can be
        "amplified" by lever effects, and surely can create large bending
        moments, if you mean that. Yeah. I am thinking the axle is centilevered out the side of the boat. Then something like a very strong bike fork supports the "tire". It'd be raised and lowered by another fitting on the fork. Maybe a hydraulic cylinder or screw actuator. The axle has to be brutally strong, since it's cantilevered.

        >> Do you instead mean that these tubes are flat against the side
        >> when in use, but FLOP down, like the support pads
        >> on a construction crane?
        >
        >Yes, exactly. And they would be held/pushed down by "sticks" that are
        >fixed close to the sheer line above the wheel.
        Now I get it. Yes, that is inherently stronger and you might get away with barn hinges if they are through-bolted to a chine. But I'd build the chine stronger than drawn, since you'll be putting holes in it.

        >Well, when in "travel" position, the hinges in my "design" would just
        >need to hold the weight of the floats.

        True, but I'm not so worried about travel position. I'm worried about strength and stability when it's sitting in dry dock position. That's why I'd tend to build the dry dock separately. No need to carry it with you.

        >What I meant were the forces at the connection of two floating
        >devices: the boat and the floats in the case that we discuss here, and
        >between the different modules in TIMS and WingNut. What are the
        >temporary forces at the connection when a wave is under the middle
        >module of three modules? or the middle module is in a trough and two
        >waves at the forward and aft module?

        Depends on how much each part weights and the distances between the center of gravity and center of buoyancy. Jim's article on sail area math shows how to draw force diagrams ans it's the same deal. You just need to make some guesses at weights.

        Or you cna save the work and build the dry dock separate. (Yes, I'm harping on this. I'd hate to see you spoil the performance of a design with appendages that could leave at the anchorage.)

        >I forgot to mention that I don't want only to stay on board, but
        >venture onto the rivers, channels, creeks, etc. I have some doubt that
        >I can anchor just where I want during night time, so I'd have to look
        >to reach a town by evening. And that means that I have to cover the
        >distance from one town to the next during daytime. A pontoon boat will
        >probably be too slow for this.

        I would not count on that. My light schooner is pretty fast under power, but pontoon boats routinely leave me behind. Many pontoon boats are either planing or semi-planing. I'm not sure which, but they definitely exceed their hull speed. I think they have those little deflector plates on the front to keep the bow from submarining in waves at these speeds. I'd look into pontoons a little more before making a decision. I bet you could get a beat up pontoon cheap and salvage the aluminum pontoons to build something. Or just get something welded. Or you could build plywood pontoos an just make them easy to unbolt so you can build new ones and replace them when they start to cause trouble.

        >I probably would be allowed to put a boat where others are already.
        >Not to build a poor man's house on the water ;)
        Bolger had a cool idea for that problem, by the way. One of his big power sharpies was designed to be a po' boy houseboat, but LOOK like a 1920's commuter yacht. So it blends in with the expensive surroundings even though it's a plywood box. Clever!

        --Rob


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