This comes at a hefty price, but seems impressive.....

Discussion in 'Stability' started by Mr Efficiency, Sep 11, 2020.

  1. brendan gardam
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    brendan gardam Senior Member

    if you read the whitepointer story, the flooding keel was designed to pass 2c survey stability tests. before wp the edencraft were a very sought after boat, still are because they are a haines hunter built to much higher standards than haines mass production.
     
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    The Edencraft is a 233, a deeper veed boat. Of course there is a definite relationship between the hull shape, the hull weight, and the way the boat sits at rest, and water ballast is a way of improving things. I expect the extra cost and complexity has deterred makers, who would rather just adjust deadrise, but in the end, the end-user decides, I think if water ballasted boats were a distinct improvement, market penetration would have happened to a greater extent.
     
  3. brendan gardam
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    brendan gardam Senior Member

    did you read the bit about the wp 263 having flooded keel to pass 2c survey stability requirements. its not for show.
     
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    I don't think anyone ever installed it for show, you can't see it !
     
  5. brendan gardam
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    brendan gardam Senior Member

    :):):):). i'll give you that one.
     
  6. Mr Efficiency
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    Mr Efficiency Senior Member

    Why do you think so few install these tanks ? At least part of the reason, has to be that you can't have a fuel tank in the same place as the ballast tank, and that is a problem.
     
  7. brendan gardam
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    brendan gardam Senior Member

    reading the seakeeper specs, their smallest gyro for boats down to 23ft needs 55amps . the seakeeper 3 for 36 to 39 ft boats needs 85 amps. that is a lot of power. the other problem i can see is how do you retrofit into an existing hull, that is a serious bit of weight and inertia to bolt to the floor. i can see it being much easier with a new hull where you can extend the engine beds or make some sort of strenghtened mount. there is a comment on the seakeeper youtube video that a unit came loose and destroyed the boat almost sinking it. aside from those issues i can see how good a gyro would be in a charter fishing boat . when i used to go out as a decky on one half the passengers would be hanging over the side giving away their breakfast when it was choppy .
     
  8. Mr Efficiency
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    Mr Efficiency Senior Member

    naturally it has to be installed as per specifications, like anything else. I actually expect these things to take off, with that sector of the market that can justify the cost. It isn't a thing for shoestring budgets.
     
  9. brendan gardam
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    brendan gardam Senior Member

    they don't have ballast tanks. it is basically a flat section a few inchs deep that runs above the v bottom. do you think a boat with twin 300 suzukis runs on a couple of 25 lt portable tanks on the deck. this is my last post on this thread, you can not be told anything even when presented with proof. i notice for all your posting about gyros you still can't answer me about the power requirements which is the elephant in the room.
     
  10. Mr Efficiency
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    Mr Efficiency Senior Member

    I have answered it, I ,mentioned batteries, and the way batteries are these days, think electric cars, then I don't think that is too much of an ask. A ballast chamber would need to be more or less centred on the COG of the boat, and have a capacity well beyond what you imply, to be worthwhile. In a 25 foot boat, at least 500 litres I would say. Can you show me the ballast set-up on that Whitepointer, and how much capacity is in it ?
     
  11. brendan gardam
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    brendan gardam Senior Member

    no i can't show what the capacity is but you can ring the builder and ask him, its not even ballast is it, the keel floods to reduce bouyancy so the hull can settle onto the chines, because it is open to the sea all the time it can't be considered ballast. your seakeeper will need that much weight in batteries they alone should be enough to keep the boat stable. now thats it , no more posts.
     
  12. Mr Efficiency
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    Mr Efficiency Senior Member

    You are getting cranky in your old age, Brendan.
     
  13. BMcF
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    BMcF Senior Member

    I'm genuinely curious...is there any data out there that shows the measured reduction in roll motions for the flooded keel applications? There are qualitative reports on the motion reduction provided by all the other roll damping solutions; some remarkable and others, not so much. That gets back to the necessity for applying the correct technology to any particular hull type...or knowing when to apply non at all.
     
  14. Mr Efficiency
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    Mr Efficiency Senior Member

    It isn't just roll motions the so-called flooding keel is intended to help, it is initial stability, and mitigating the effects of people moving around causing heel. Of course it works to some extent, despite claims that because it is open to the outside, it can't be considered ballast, but in practical terms it is. It is entrained, and can't slosh from side to side when filled, and if the air vent is closed, is pretty well trapped.
     

  15. BMcF
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    BMcF Senior Member

    I knew all that...just wanted to see some numbers. Active motion reduction will never, ever have anything much in common with a flooded keel. That was my point. Similar situation with bilge keels. They might reduce motions by 10-15% in best case...while active solutions can achieve 90% reductions in some cases. Apples...oranges....
     
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