Practical and Ideal Berth Design

Discussion in 'Boat Design' started by Grant Nelson, Jun 1, 2008.

  1. DanishBagger
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    DanishBagger Never Again

    Well, a rolly anchorage can be quite unpleasant in a wide berth. Or even if it's "just" too far off the center of roll.
     
  2. Westfield 11
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    Westfield 11 Senior Member

    While I agree with your point in theory, in practice I have found that 50k to 100k lb. boats just don't roll that much at anchor. Pitch, perhaps, but unless stern tied they just weathervane into the wind. Certainly things may be different in different cruising grounds. and I will yield to your greater experience in these matters.

    Michael
     
  3. DanishBagger
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    DanishBagger Never Again

    Well, in that "roll" of mine, I thought "roll", "pitch", "yaw" and every other of those words included. I know, I should have used a more correct terminology, I'm sorry.

    Anyway, I disagree, that once you go to about 50k or 100k lbs the boat won't do any of those things, that's simply not true. Well, in some places it is, I guess, just like you point out the opposite.

    But I have seen huge boats roll around, pitching and yawing at anchor, so it's not just the weight that does it.

    Anyway, I think one should try to have a really good seaberth for at least half the crew, preferably for everyone if venturing far from land (and thus being able to heave-to for hours, having a rest).

    I really do respect the dashews, and they're serious about rolling. There's a reason even their 83 foot FPB have flopper stoppers and watertanks on top of the pilot house. It's certainly not because it would just be a fun thing to do, it's because it rolls at anchor, even if does weigh around the 100.000 lbs fully loaded if I recall correctly.
     
  4. Westfield 11
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    Westfield 11 Senior Member

    Again, it's horses for courses, the mission of the Dashews is different from Monk and DeFever's as is reflected in the boats them selves. Wind Horse is an all weather offshore voyager. The top heavy shorter range DeFever is a coastal cruiser. The Monk is somewhere in between, but still biased away from being optimised for serious offshore work.

    Any boat that I own will only cross oceans on the deck of a freighter, which, considering the cost of fuel and wear and tear on the vessel, has become an attractive option. It is no longer necessary to travel from one cruising ground to the next on one's own bottom. But the implications of that is another discussion for another thread.
     
  5. DanishBagger
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    DanishBagger Never Again

    When I speak of the Dashew's FPB in this context, they're talking roll, bobbing, and so forth _in anchorages_. I am not talking about their hydraulic stabilisers, or the fish they can attach to the outriggers while underway. It's flopper stoppers used in anchorages, watertanks at the top of the pilothouse, which, by their own admission has only been used to slow down the rolling motion in an anchorage.

    Anyway, as even they are rolling when they are not moving along, be it in hard-to-navigate places such as in between coral reefs, or simply at anchor in a motorboat that is pretty big, has a low center of gravity, and - get this - even sports a keel (yes, it does), really puts the argument that if your boat is weighing between 50k and 100k lbs. then it doesn't (can't) roll utterly to shame in my book.
     
  6. TeddyDiver
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    TeddyDiver Gollywobbler

    [​IMG]

    So??? clear, bit gusty weather with 1-1.5m waves:p
     
  7. Westfield 11
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    Westfield 11 Senior Member

    I never said that they won't roll, just that IMHO they don't roll "that much". I can only speak from my own (limited) experience.
     
  8. DanishBagger
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    DanishBagger Never Again


    At twelve knots, btw.
    But my point was not the weather, my point was that it's quite a big boat, weighing between 50.000 and 100.000 pounds, yet the owners-cum-designers claim they still roll in anchorages. This despite them trying to sell this type of boat.



    Ah, I see, so you weren't conveying that in a boat between 50.000 and 100.000 pounds, rolling at anchorages are unnoticable, that boats that size would never need a sea berth in an anchorage …
     
  9. TeddyDiver
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    TeddyDiver Gollywobbler

    I've allways found a bit strange using knots with wind speeds. Is it something like "mild kuling"?
    Anyway the helicopter was still flying to take the pic so not very "hard weather". Seldom see pictures taken of a boat then for obvious reasons..
     
  10. Pericles
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    Pericles Senior Member

  11. DanishBagger
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    DanishBagger Never Again

    No, no, I meant they were sailing/driving at twelve knots. Boat speed, that is.

    Again, the picture was not to show harsh weather, but to show a dedicated design and the size of that thing.
     
  12. FAST FRED
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    FAST FRED Senior Member

    "I figured I'd also google Concordia Berth and post a picture here of a nice one, thinking I'm propably not the only one ignorant to what such a thing is."

    Thanks for the try but that may be a berth in a Concordia , but its NOT a "Concordia Bunk"., as least as I have seen them.

    The Concordia bert has a pipe fitted to the boat at two ends that does NOT touch the hull sides.One edge of the canvas is attached.

    The there is a second pipe mounted lower that ho0lds 3 curved pivoting arms. The top of the arms have the second pipe for the bunk.

    The curves arms accept ash battens that form a very comfortable seat back.

    When closed and used as a seat back the bunk is out of sight and holds all the bedding , and some crew storage.
    Upon being swung open the bunk is ready to use.

    Haven't found a photo on line , and it will be November before I can take a shot of our installation.

    FF
     
  13. DanishBagger
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    DanishBagger Never Again

    Ah, I see. Thanks for the clarification, Fred. It's much appreciated. Looking forward to see a real one, then. Hopefully someone can find a picture before november, though. :)
     
  14. Westfield 11
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    Westfield 11 Senior Member

    If you need a sea berth when you are in an anchorage, then you just picked the wrong place to drop the hook. I assume you are talking about an actual anchorage as most understand it. I always thought that "anchorage" implied a modicum of protection from wave if not wind and usually both. If you are anchored offshore in 50 to 100+ feet in open water, Yes, then I agree you do need a sea berth. You also need to have your head examined too IMHO unless you are getting paid for the experience (fishing?). Does not sound like pleasure cruising to me.

    I know all about the arguement of having a vessel capable of safely withstanding any condition as one can't predict the sea. In that case, I submit that a submarine would fit the bill and anything less would be inadaquate. Well, I exagerate, an icebreaker would do as well. Perhaps even a pilot boat with a steel hull and superstructure, and no more than 1 or 2 tiny portholes. Again, does not sound like a pleasure boat either.

    At 72', the Dashew's Wind Horse is a rather light boat @ 50K lbs and still not really a very heavy displacement vessel @ 75k. Reading their web site it seems like it was built to be able to surf down wave fronts when offshore. This certainly implies a lighter type of design, one that will jump out of displacement mode easily. No wonder they need pipe berths, safety harnesses and ballast tanks to slow the roll, as a light boat will have a quick uncomfortable motion in the best of conditions. This is not at all the behavior of a traditional displacement cruiser at sea nor at anchor. Certainly not the behavior of the two designs I referenced earlier and these are semi-displacement hulls operated in displacement mode.

    I see from the post above that Wind Horse is moving at 12 knots, is that above hull speed for a 70' waterline? If so then it is not a displacement boat at all, if it can surf down waves, then is it a planning hull instead? You guys are the experts.....
     

  15. DanishBagger
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    DanishBagger Never Again

    Actually, Wind Horse is 83 feet, not 72. And you're right, it's pretty light for boat that size. On the other hand, it's quite low, and although the lack of height means it will roll quicker, a taller one will still roll. Especially considering how the taller superstructure will be affected more by wind, which will mean you might get lucky that the wind forced you sideways onto the waves.

    Btw, their boat doesn't roll _that_ fast, go read their website. They even have numbers (yes, they're number-geeks*).

    * In a good way, of course.
     
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