Hallberg-Rassy 48 - Sunk after whale strike

Discussion in 'Boat Design' started by JosephT, May 24, 2017.

  1. JosephT
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    JosephT Senior Member

    I read this news a bit ago and I'm curious if there has ever been a yacht hull design standard to withstand a whale strike. It seems a steel hulled vessel would fair better, but it all depends on the type of steel. Then again, there are impact resistant fibers (e.g. aerospace grade S3 fiberglass with satin weave) which is designed to withstand impacts MUCH better vs. give way. The typical low budget, mass produced fiberglass chop hulls don't offer much in this regard.

    What say you yacht design + composite experts?
    What's your favorite impact resistant composite layup spec?
    Should bluewater yacht designers ignore this or consider an improvement?

    Granted it would be more expensive, but for a bluewater yacht (tough enough to sail between continents) it would be worth it. These poor chaps were over 350 miles offshore. Whale strikes are random, but they are increasing with the number of boats today & slowly recovering whale populations.

    Three British sailors rescued after their yacht collides with a whale - YBW http://www.ybw.com/news-from-yachting-boating-world/three-british-sailors-rescued-azores-yacht-collides-whale-53284
     
  2. PAR
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    PAR Yacht Designer/Builder

    You just can't design to every possible eventuality. To do so just makes the yacht unnecessary heavy and costly. Some classes of yacht might require this approach, but 98% don't, so . . . It's a bit like ordering a custom ice breaking bow, just in case, but to never need to use this requirement. Lastly, sometimes, it just boils down to luck and designing around your rabbit foot's current running record, isn't a good business plan.
     
  3. messabout
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    messabout Senior Member

    A rather gripping movie titled; All Is Lost has Robert Redford, alone in who knows where, perhaps the Indian ocean. His boat strikes one of the not infrequently lost floating steel containers. One has to wonder whether the apparently fully found boat would have gone to Davy Jones Locker, had it not been made from the cheap and dirty method of the chopper gun.

    Whales and steel containers are equally hazardous. I am tempted to claim that the whale may cogently opt to to avoid a collision while a container has no such intentions.

    For those salty sailors who have not seen the movie... I recommend it, first for the quality of the acting and then for the realities of the plot.
     
  4. sharpii2
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    sharpii2 Senior Member

    I'd go with mild steel, with a long keel. Steel has excellent yield properties, meaning it absorb the blow without rupturing.

    The Hull/Keel joint is an area of high vulnerability. The shorter and deeper the keel gets, the more this is true. If the whale strikes the keel from the front or rear, the keel can function like a giant can opener, even with a steel boat. It is difficult to imagine any construction material where this is not true.

    But sailboats get sunk by ship collisions too. And nobody is going to ask for a construction material which can withstand that. It may be better to ask if there are affordable ways of making a vessel more able to survive such damage without quickly sinking. Separate bow and stern compartments come immediately to mind. If it's possible to keep the vessel afloat long enough, there may be a way of making make-shift repairs, which are good enough to get it back to port. Another approach, which may be even less expensive, from a production point of view, might be to make the boat out of foam and fiberglass, but with the foam being major structural component. This would require thick foam with thinner layers of fiberglass.

    If anything, this construction method would be even more brittle than the foam sandwich construction used today. But this very brittleness may help save the ship. It would localize the damage, allowing the vessel to maintain most of its structural integrity. The volume of the immersed foam would keep it afloat.

    I know Kevlar armor can stop bullets, allowing its wearer to survive. But such would not be the case with cannonballs. The bullet kills by first penetrating its victim, then using its remaining kinetic energy to rip its victim up from the inside. A cannonball doesn't have to penetrate to kill. The blunt force it provides does the trick. A ''spud gun", which launches half pound potato at maybe 300 ft/sec, may be more effective against an active shooter wearing body armor than a high power rifle.
     
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  5. DCockey
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    DCockey Senior Member

    What boat was made with a chopper gun?
     
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  6. DCockey
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    DCockey Senior Member

    What type of foam can be a "major structural component"?
     
  7. sharpii2
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    sharpii2 Senior Member

    I've seen it and I recommend it, even though there were some serious plot inconsistencies. Such as why did he turn in for the night before he finished bailing out his boat? There was not even a hint of a reason why not.

    Does anyone use chopper-guns? I thought that practice went out during the late 60's.

    Doesn't everyone use hand-layup?
     
  8. sharpii2
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    sharpii2 Senior Member

    Maybe higher density stuff, 4 to 6 inches thick.
     
  9. philSweet
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    philSweet Senior Member

    Joseph, you might want to read Dougal Robertson's account of an attack by a pod of killer whales. They rammed the boat at full chat, breaking the keel off. The boat sank out of sight in one minute. If I recall correctly, it was a twin-keeled boat, and there has long been a notion that twin keels look like they belong to something edible to killer whales. They seem to get a disproportionate number of attacks.

    Survive the Savage Sea (Sailing Classics): Dougal Robertson: 9780924486739: Amazon.com: Books https://www.amazon.com/Survive-Savage-Sea-Sailing-Classics/dp/0924486732
     
  10. Mr Efficiency
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    Mr Efficiency Senior Member

    Sperm whale is likely the culprit, they are well know to deliberately ram quite large vessels. There are now a vast number of Humpbacks migrating through heavily (boat) trafficked areas,compared to 30 or 40 years ago, but collisions seem to be rare, and rammings less so.
     
  11. sharpii2
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    sharpii2 Senior Member

    Nope. The Lucette had a single, long keel. It was made out of plank-on-frame wood. The damage was closer to the turn of the bilge, IIRC. I read the book more than 30 years ago. Fascinating story. At least one killer whale did hit the keel, and died for its trouble. They sailed most of the way to the South American coast, before they were picked up by some fisherman, some 6 to 8 weeks later, IIRC. Their raft broke up within a week or two, and all six of them were forced into their nine foot dinghy. Parts of the inflatable raft were cleverly used to add buoyancy to this severely overloaded dinghy They fashioned a rudimentary square sail. I believe they were less than 200 miles from the coast when they were rescued. There was at least a good chance they would have made to land on their own, had they not been rescued.

    There was another incident, not too many years later, where a couple sailing a triple-keel Golden Hind 31, made out of fiberglass covered plywood, was struck by a killer whale, or so they believed. The strike broke off one of the side fins, which were at least as deep as they were long. This put a huge hole in the hull, which quickly sank. They drifted for months in their raft before they were rescued.

    The going theory, during that era, was that it was the bottom paint color which provoked the attacks.
     
  12. JosephT
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    JosephT Senior Member

    These are some harrowing whale attack stories. Sharpii2 states the some keels can be torn off and act like a can opener and sink a boat in minutes. HOLY COW! And your story of a pod of killer whales attacking a twin keeled sailboat (because it looks edible) raises some concerns. I can see starving Orcas smashing their brains out trying to kill a big twin finned fish of a sailboat. :eek: Based off of this feedback it appears the keel/hull joint is indeed vulnerable.

    I'm inclined to agree with sharpii2 that mild steel with a longer, more streamlined single keel that is integral to the hull is the way to go. They definitely survive better than the composite boats, which have fracgtured on blunt impacts time and again. A Kevlar reinforced hull is also a consideration, but I know repairs on kevlar are a pain in the butt (sanding fibers = fraying). Here's a good write-up on steel vs. fiberglass. Many good points are discussed. So long as the boat is properly coated and maintained rust can be kept to a minimum. A stainless steel hull would be the ultimate, but very costly.

    Cold Hard Steel - PassageMaker http://www.passagemaker.com/cruiser-reviews/cold-hard-steel
     
  13. Squidly-Diddly
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    Squidly-Diddly Senior Member

    this is why I'd want SOME sort of emergency system to provide positive buoyancy in any keelboat, and preferably more than one system.

    probably things(more than one, more than a dozen) that inflate inside the cabin.

    something like heavy duty 33 gallon trash bags with compressed CO2 or maybe even baking soda and vinegar (all that extra soda and vinegar is good for cleaning, too, lol).

    They would be positioned with Velcro up in nook and crannies in places where their inflation wouldn't hinder other emergency operations, such as berths.

    I figure a mess of relatively small air bags more or less tethered in place spread around the interior would also spread their lifting load well and not themselves cause any structural damage.

    Size them to be able to be easily passed out through main hatchway, or even a large skylight. About 20"x60". Or maybe single extra long air mattress shaped!

    Tough enough so MOST of them with survive the minor chaos of inflating in a sinking boat, but weak enough to emergency deflate with cheap knife or with a tear strip.

    Have them able to do extra things like air mattress, emergency raft especially when ganged together, and emergency fenders.

    Maybe some system that would inflate them with ambient air before becoming submerged. Battery powered fan-pack and auto-sealing valves? Batt-system would make it easy to activate the units remotely via automatic or manual broadcast. Use standard D etc so it doubles as spare batt holder.


    Something that can be added on easily depending on the mission, rented, borrowed, leased and/or FedEx overnighted, rather than needing to be planned and paid for when the hull was being born.
     
    Last edited: May 25, 2017
  14. PAR
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    PAR Yacht Designer/Builder

    Most incidents with whales aren't bow on or leading edge of the keel on, but broadside or rather oblique to the hull or appendage. With many tons of cantilever on a fin, it's just not something you need to consider, unless you plan many thousands of miles in certain regions of the seas. Adding several times the strength than necessary for the very low odds of these occurrences, seems obsessive at the very least. I'm not sure how many tens of thousands of miles I have in blue water, but after several crossings and playing in areas active with big fish like critters, I've never even come remotely close to a collision and wouldn't want to carry around several extra tons of reinforcement, just in case, let alone pay for it during construction or retrofit.
     

  15. Remmlinger
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    Remmlinger engineer

    The risk of colliding with other ships or floating objects is quite different from the collision-risk with a whale. Keeping a good look-out and steering clear will not prevent the collision with a whale. On a trip from the Azores to the Channel in a 33ft fiberglass yacht we were suddenly surrounded by a pod of large Fin whales. They were curious, swam parallel to the boat at the same speed, dived and surfaced again. I started the engine and tried to escape, which was a mistake, because I sailed at an angle to their previous path. A few seconds later a huge body emerged directly in front of our boat, blew and started diving. While diving the whale hit the foreship with his fluke so hard, that a sleeping crew fell out of her bunk. No damage occurred to the boat.
    I have no idea how one could avoid severe damage to the boat if the whale surfaces directly under the boat.
    Uli
     
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