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Re: Micro with plate centerboard

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  • William
    I go away to Asia for a few weeks and miss out on my favorite topic (Micro/LMs)? What luck. Mason, great report on the centerboard mod. I d love to see a
    Message 1 of 38 , May 31 1:09 PM
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      I go away to Asia for a few weeks and miss out on my favorite topic (Micro/LMs)? What luck. Mason, great report on the centerboard mod. I'd love to see a comparison of GPS tracklogs.

      I have been "knocked down" once in my LM, on Lake Erie. There are two ways I can see it happen. The first happens when running, with sharp and high waves coming from abeam. The flat bottom of the M/LM rides the swells easily, but also heels considerably, and if the waves are steep enough and spaced close-enough together, that long boom can dig into a passing wave. When this happens, the mainsail sheets in tighter (no matter how much you ease the main sheet), as the boom digs into the wave. The boat heels further, the boom digs deeper into the wave, and so on. I recall Phil Bolger wrote something about this in regards to a vice of cat boats with long booms? Anyway, I had it happen to me a few times on Lake Erie, but it was never serious enough to result in a knockdown, although I could see it happening.

      My knockdown occurred when a sudden gust of wind blew me over (again on Lake Erie). I usually sit with my back to the wind on the windward side and I did not see the approaching gust. Before I could ease the mainsheet I was heeled at least 70 degrees- not enough to put the mast head into the water, but enough that I was standing on the gunwale, looking down into the depths of the lake. Time slowed like cold molasses. She popped up almost instantly and I reefed.

      I cannot speak of the M, but my LM plans show 11 cu feet of foam total. I recall that one cubic foot will float approx. 62 lbs, so the flotation from the plans will float 682 lbs. The estimated weight of my LM (with .5 inch thick sides and top deck, and the added structure of the self bailing cockpit) without the outboard is 1870 lbs. The plywood(26 cubic feet) will float an additional 1612 lbs. In total, a stock LM should float 2,294 lbs. That's not bad. A heavily laden boat would sink, a lightly loaded one might stay awash.

      I altered my LM by adding more foam (and floatation space) under the cockpit sole. I now have a little over 20 cubic feet of floatation space which gives me 1240 lbs of floatation, along with the 1612 lbs in ply. I feel more comfortable with this margin of error (2852 lbs of floatation for a ~1900 lb boat). Regardless, I don't think a Micro or LM would sink as quickly as some plastic boats (such as J24's, which seem to sink with some frequency).

      Love these discussions.

      Bill, in Texas
      Long Micro Pugnacious

      --- In bolger@yahoogroups.com, Bruce Hallman <hallman@...> wrote:
      >
      > On Thu, May 27, 2010 at 10:33 AM, John Bell <yonderman@...> wrote:
      > >
      > >
      > >
      > > A long time ago I heard a story from Texas that a Micro got knocked down, flooded, and sank. I'm not sure there is 450 lbs of positive bouyancy in the wood structure alone to keep a Micro afloat.
      > >
      > > I don't know if it's true, though.
      > >
      >
      >
      > (I have the Chinese Gaff Micro Navigator design rig, not the basic
      > Micro rig.) But with my sail rig, the few times I have got caught in
      > overpowering winds, the way the boat behaved was to lean over a bit,
      > and then then quickly dump the wind out of the mainsail while rapidly
      > spinning around to point directly up into the wind. That is why I say
      > I cannot imagine getting knocked down, because the boat naturally
      > spins and heads up into the wind automatically and seemingly idiot
      > proof.
      >
      > The only way I could imagine turning over would be if one got caught
      > in a big surf break, and even then I am not sure how she would behave.
      > My guess is that she would lean over about 60 degrees, (which would
      > lift the fin keel up to a point that it wouldn't have any grab on the
      > water), and then she would skitter along like a cork.
      >
    • William
      I go away to Asia for a few weeks and miss out on my favorite topic (Micro/LMs)? What luck. Mason, great report on the centerboard mod. I d love to see a
      Message 38 of 38 , May 31 1:09 PM
      • 0 Attachment
        I go away to Asia for a few weeks and miss out on my favorite topic (Micro/LMs)? What luck. Mason, great report on the centerboard mod. I'd love to see a comparison of GPS tracklogs.

        I have been "knocked down" once in my LM, on Lake Erie. There are two ways I can see it happen. The first happens when running, with sharp and high waves coming from abeam. The flat bottom of the M/LM rides the swells easily, but also heels considerably, and if the waves are steep enough and spaced close-enough together, that long boom can dig into a passing wave. When this happens, the mainsail sheets in tighter (no matter how much you ease the main sheet), as the boom digs into the wave. The boat heels further, the boom digs deeper into the wave, and so on. I recall Phil Bolger wrote something about this in regards to a vice of cat boats with long booms? Anyway, I had it happen to me a few times on Lake Erie, but it was never serious enough to result in a knockdown, although I could see it happening.

        My knockdown occurred when a sudden gust of wind blew me over (again on Lake Erie). I usually sit with my back to the wind on the windward side and I did not see the approaching gust. Before I could ease the mainsheet I was heeled at least 70 degrees- not enough to put the mast head into the water, but enough that I was standing on the gunwale, looking down into the depths of the lake. Time slowed like cold molasses. She popped up almost instantly and I reefed.

        I cannot speak of the M, but my LM plans show 11 cu feet of foam total. I recall that one cubic foot will float approx. 62 lbs, so the flotation from the plans will float 682 lbs. The estimated weight of my LM (with .5 inch thick sides and top deck, and the added structure of the self bailing cockpit) without the outboard is 1870 lbs. The plywood(26 cubic feet) will float an additional 1612 lbs. In total, a stock LM should float 2,294 lbs. That's not bad. A heavily laden boat would sink, a lightly loaded one might stay awash.

        I altered my LM by adding more foam (and floatation space) under the cockpit sole. I now have a little over 20 cubic feet of floatation space which gives me 1240 lbs of floatation, along with the 1612 lbs in ply. I feel more comfortable with this margin of error (2852 lbs of floatation for a ~1900 lb boat). Regardless, I don't think a Micro or LM would sink as quickly as some plastic boats (such as J24's, which seem to sink with some frequency).

        Love these discussions.

        Bill, in Texas
        Long Micro Pugnacious

        --- In bolger@yahoogroups.com, Bruce Hallman <hallman@...> wrote:
        >
        > On Thu, May 27, 2010 at 10:33 AM, John Bell <yonderman@...> wrote:
        > >
        > >
        > >
        > > A long time ago I heard a story from Texas that a Micro got knocked down, flooded, and sank. I'm not sure there is 450 lbs of positive bouyancy in the wood structure alone to keep a Micro afloat.
        > >
        > > I don't know if it's true, though.
        > >
        >
        >
        > (I have the Chinese Gaff Micro Navigator design rig, not the basic
        > Micro rig.) But with my sail rig, the few times I have got caught in
        > overpowering winds, the way the boat behaved was to lean over a bit,
        > and then then quickly dump the wind out of the mainsail while rapidly
        > spinning around to point directly up into the wind. That is why I say
        > I cannot imagine getting knocked down, because the boat naturally
        > spins and heads up into the wind automatically and seemingly idiot
        > proof.
        >
        > The only way I could imagine turning over would be if one got caught
        > in a big surf break, and even then I am not sure how she would behave.
        > My guess is that she would lean over about 60 degrees, (which would
        > lift the fin keel up to a point that it wouldn't have any grab on the
        > water), and then she would skitter along like a cork.
        >
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