Seaworthiness

Discussion in 'Stability' started by Guillermo, Nov 26, 2006.

  1. Guillermo
    Joined: Mar 2005
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    Guillermo Ingeniero Naval

    Yes Bataan, they seem both to have Norse influence in their origins. As the dornas are rather intended mainly for protected bays use (the South Galician Rías) their bows are not so high as in the Coble.

    P.S. I've realized the coble image you posted is the same member Angelique uses as avatar in this Forum :)
     
  2. BATAAN
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    BATAAN Senior Member

    Ripped from WB forum.
     
  3. Pericles
    Joined: Sep 2006
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    Location: Heights of High Wycombe, not far from River Thames

    Pericles Senior Member

    Guillermo,

    Does rebuilding require compliance with the RCD? I am thinking rebuilt and sold before the 5 year period expired. Just the hull remained as far as I can see with this runabout.

    Scroll down to AdrianK.

    http://www.boote-forum.de/showthread.php?t=18229&page=18

    How many parts does one have to have to constitute a rebuild?

    I have an idea:idea:

    Regards,

    Perry
     
  4. Crag Cay
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    Crag Cay Senior Member

    The RCD has nothing to do with rebuilds, or building classic designs in predominately the same materials as the original, or boats built exclusively for racing, etc. Nor has it anything to do with governments trying to control the use of boats by their citizens.

    The RCD is solely to liberalise trade within the EU and as such sets a common requirement for vessels at the point they are first put on the market.

    You could build and sell a GP14 in wood without any RCD compliance, but if you were to offer one in composite, I think you would be wise to comply with Cat D. That's not onerous as it's essentially self assessment.
     
  5. Guillermo
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    Guillermo Ingeniero Naval

    Trade liberalisation and common requirements, yes, but with users' safety in mind.

    Perry, why do you want to rebuild a boat in such a bad condition? :eek:

    Just keeping a couple of frames of the original (or even nothing, in fact) can be considered a rebuild, as far as you tighten to the precise design with no significant alterations. RCD has nothing to do with this, as Crag says.
     
  6. Pericles
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    Pericles Senior Member

    Two certainties, death & taxes.

    Start with the ship's bell and a few frames and who knows what the original looked like?

    http://www.life.com/image/89368235

    http://www.life.com/image/89368303

    A rebuild avoids the unnecessary complication of the RCD & CE mark, because the Boat Safety Scheme requires good standards of fitting out and maintenance.

    http://www.boatsafetyscheme.com/site/GettheGuide_7.asp

    It also means the vessel can be sold on at any time.

    Crag Cay,

    This line made me smile "Nor has it anything to do with governments trying to control the use of boats by their citizens."

    The fundamental difference between English Common Law and the Napoleonic Code is that unless something is specifically regulated by ECL, there is an assumption is that a person is free to do something i.e. there are plenty of very capable British sailors who set out to sail without a document of competence. OTOH, in NC, unless there is a document giving permission to take a of action, the assumption is that the action is prohibited. It's just a difference in mindset. Thus, an English & a Frenchman both have to have a certificate of competence to hire a day boat on French canals, whilst neither are so required in the UK. Turn up, cough up, take off.;)

    http://www.boatsthames.com/dayboats.html

    "My son," said the Norman Baron, "I am dying, and you will be heir
    To all the broad acres in England that William gave me for share
    When he conquered the Saxon at Hastings, and a nice little handful it is.
    But before you go over to rule it I want you to understand this:–

    "The Saxon is not like us Normans. His manners are not so polite.
    But he never means anything serious till he talks about justice and right.
    When he stands like an ox in the furrow – with his sullen set eyes on your own,
    And grumbles, 'This isn't fair dealing,' my son, leave the Saxon alone.

    "You can horsewhip your Gascony archers, or torture your Picardy spears;
    But don't try that game on the Saxon; you'll have the whole brood round your ears.
    From the richest old Thane in the county to the poorest chained serf in the field,
    They'll be at you and on you like hornets, and, if you are wise, you will yield.

    "But first you must master their language, their dialect, proverbs and songs.
    Don't trust any clerk to interpret when they come with the tale of their wrongs.
    Let them know that you know what they're saying; let them feel that you know what to say.
    Yes, even when you want to go hunting, hear 'em out if it takes you all day.

    They'll drink every hour of the daylight and poach every hour of the dark.
    It's the sport not the rabbits they're after (we've plenty of game in the park).
    Don't hang them or cut off their fingers. That's wasteful as well as unkind,
    For a hard-bitten, South-country poacher makes the best man- at-arms you can find.

    "Appear with your wife and the children at their weddings and funerals and feasts.
    Be polite but not friendly to Bishops; be good to all poor parish priests.
    Say 'we,' 'us' and 'ours' when you're talking, instead of 'you fellows' and 'I.'
    Don't ride over seeds; keep your temper; and never you tell 'em a lie!"

    Rudyard Kipling.

    Yours, lightheartedly,;)

    Perry
     
  7. Guillermo
    Joined: Mar 2005
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    Guillermo Ingeniero Naval

  8. Lazy_Jack
    Joined: Jun 2011
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    Lazy_Jack New Member

    Hi there All -

    Can I just say this long lived thread has been most informative, though I haven't manged past page 50 or so.

    Sorry to resurrect it - but I have a genuine question:

    Since this thread started 5 years ago how many Pogos, Open 40's or other similar ULDB bluewater yachts have capsized or sunk?

    The early parts of this thread had lots of stats, but some of these designs were quite new back then.

    In the last 5 years the numbers of these yachts have multiplied vastly, most races are full of them and by now such yachts must have been in every sea condition imaginable.

    So are there any cautionary horror stories out there?

    This isn’t a troll: I am getting back into sailing after 20 years off and I find these modern designs appealing. However being from Tasmania I have also been in some of the worse sea conditions you can imagine.

    Please note I’m interested in case studies and proven examples of unseaworthy behaviour in these new craft – not just the opinions that were exhaustively aired in the first have of these thread.

    One capsize? Ten? What’s the current tally?

    Cheers,
    LJ
     
  9. sharpii2
    Joined: May 2004
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    sharpii2 Senior Member

    Hi, Lazy Jack.

    I don't have the numbers your looking for, but I do have something to say that might be interesting to you and may save you a lot of heartache down the line.

    There are two basic types of these vessels:

    1.) ones that have canting ballast and
    2.) ones that don't.

    The ones with canting ballast have a bulb extended from a streamlined strut. This strut is on a pivoting axle, so, with the help of hydraulic rams, the bulb can be canted to windward. They usually have two dagger board like appendages, fore and aft the ballast strut to resist leeway when the strut is canted. Some of them have twin, retractable, dagger boards on either side of the ballast strut, where the one to windward is always retracted.

    The ones without have the ballast bulb attached to a rather deep, short, glider wing like keel.

    Both can be quite seaworthy if constructed properly. Since both deal with highly concentrated loads at or near the keel/hull joint, they must be carefully designed and built with the best workmanship and materials available.

    But that is only the seaworthy part of the story.

    The other part of the story is sea kindliness. And that is something these boats lack. Since they are designed to maximize speed, they have flatish, dinghy like sections in their hulls to facilitate planing. Down wind, they give an exhilarating ride, sometimes reaching runabout speeds of 30 kts or more. Up wind, they pound, thrash, and snap roll, as the flatish hulls try to conform to the wave surface and the deep bulbs try to conform to gravity.

    If you're up to this kind of treatment, it can be great fun.
    If not, it can be a miserable experience. One Around Alone(r) skipper likened sailing up wind in these vessels to driving a truck with square wheels.

    These vessels are not sea kindly. And this lack of sea kindliness puts incredible strains on the entire boat, from the bulb attachment all the way to the mast head. For this reason and because they are designed with minimal safety factors, to keep them light and further enhance their speed, they are likely to have short useful lives. Brand new, they may be entirely sea worthy. Previously owned, they may very well not be.

    Years ago there was a post by a fellow who had one of these in his boat shed and was trying to sell it. In his post, he mentioned a litany of sins, including a separating hull/deck joint and other problems I can't remember.
    It boiled down to he didn't dare sell the thing for fear of liability.

    The problems I have heard about most deal with the fixed, non canting keels. They have a tendency to fail at the keel/hull joint as the metal that the keel is made of eventually fatigues. Other failures are weld joints, and one was with a metal plate that the keel was attached to being wrenched right out of the FRG hull, leaving a huge hole in it.

    These are just a few things to keep in mind when you consider this type of vessel.
     
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  10. Lazy_Jack
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    Lazy_Jack New Member

    Thanks for that DSharpii - thats exactly the sort of well balanced reply I've been looking for.

    The keel-hull join is a major concern - although more conservative builders may reinforce the area with a metal or carbon grid (which may have their own issues) theres no such reinforcement apparent in many models. Long term fatigue isnt something I've considered yet - will have to delve into construction methods and materials used...

    Love the square wheels quote. I've read many posts on other forums where the pros of these designs have been sung at great length, so its good to hear the other side. I've been wondering if deep bulbs and light rigging will help or hinder seakindiness in such conditions? The opposing view I guess is that you can always power down and gain more stability - but that would only work in moderate sea states.

    Do also let me know if anyone has any cautionary tales of unseaworthy behavior in big seas.

    Cheers,
    LJ
     
  11. sharpii2
    Joined: May 2004
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    sharpii2 Senior Member

    Slowing down might help, but these boats have so little heft that a short, steep sea may stop them cold, if they are moderately canvased. So. Not only do they have an enormous press of sail, they need it. It is the press of sail that keeps a sailboat from rolling in a seaway. The more initial stability a boat has (ability to carry sail) the greater amount of sail it needs to keep it from rolling.

    When it comes to the two types of these boats, I prefer the canting ballast versions. With the canting ballast it is possible to incline the boat to leeward, shortening its hull form righting arm, and perhaps improving its upwind manners. I don't know if such has ever been tried, but with dinghies the technique works quite well in light air and glassy seas. With the fixed keel versions, there is nothing you can do. You just have to take it. Take it and console yourself with the fact that, as one prominent sail boat design critic once said, comparing these deep bulb and canting keel boats to more conventional ones is like comparing propeller planes to jets.

    High initial stability gives you the ability to carry lots of sail and go fast, but it also makes for a rough ride in any kind of seaway.

    You also have to consider a lot of these boats are self righting in a more marginal sense of the word. The ultimate self righting boat can right itself from a 180 deg. capsize. Few real boats can do that. Usually, the righting curve runs out at about 120 to 150 deg. capsize. Fortunately this is often sufficient. Usually the very waves that capsize it knock it back upright. With a 120 deg. righting curve, the natural proclivity of the boat is to float up right. (240 deg, port and starboard upright, vs. 120 deg. port and starboard upside down)

    But if you have a boat that has low sides in proportion to its beam, as this type of boat usually has, there is less of it for waves to hit, once it's upside down. Not only that, but there is far more mast and rigging under the water to dampen any righting force the waves might impart. For this reason, at least one of them stayed inverted from the time communication from its skipper broke off to when it was found six months later. So. Even if rules were made in their various racing classes to mandate they be stable to at least 120 deg., that may still not be enough.

    Another rule to remember: What has high initial stability upright, is very likely have high initial stability upside down.

    A very narrow hull with deep sections and a deep bulb keel would probably be more seaworthy than most conventional boats, but nowhere near as fast as today's ULDB, even with the same length and displacement. This is because it will have less initial stability.

    Ya takes ya choices, then ya pays ya money.
     
  12. Roly
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    Roly Senior Member

    So ya ma as wall have a multi. (And not spill your beer most of the time.)
     
    Last edited: Jun 5, 2011
  13. souljour2000
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    souljour2000 Senior Member

    This may be my favorite thread in cyberspace....thanks everyone for your expert opinions whether "right" or "wrong"...
     
  14. sharpii2
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    sharpii2 Senior Member

    Two reasons:

    1.) Most of these boats race in contests that expressively forbid mult's (and ya wonder why that is), and
    2.) a ULDB has at least some hope of recovering from a capsize. A multi has none.

    I have been thinking of a self rescuing system for a multi, but, then again, it's up to the racing rules committees to mandate such a thing (for multi hull racing). It adds weight, complexity and cost. They probably much rather use other racers as life guards.

    Anyway. The system would use air bags and ballasted centerboard(s) that could be locked down. It would also require one hull to be a designated "sinker" and at least one to be a designated "floater". The system would be best used in relatively calm conditions, so one would have to ride out the storm while inverted, then try self rescue afterward.

    I don't expect there would be many takers.

    For this reason, I believe multis are best for cruising, despite their superior performance potential. No cruising skipper is going to take any where near the risks that a racing skipper will. And the superior performance comes at a relatively low cost.
     

  15. Angélique
    Joined: Feb 2009
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    Location: Belgium ⇄ The Netherlands

    Angélique aka Angel (only by name)

    Far as I know the drawing was made by Hans Vandersmissen (RIP). I've ripped it from here . . :eek:

    [​IMG]

    The drawing was made to show one of their inspirations for their Wadkrabber.

    (more info and pics and drawings on the Dutch version of that site)

    [​IMG]
    Wadkrabber

    Cheers,
    Angel
     
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