cheeky rafiki

Discussion in 'Stability' started by peter radclyffe, May 21, 2014.

  1. Nick.K
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    Nick.K Senior Member

    But by extension then all beginners are foolish? Well, someone close to me would say that going to sea in any small boat is foolish whatever (a sore point!). Not everyone can be an expert on boat design and construction and probably these crew felt that they had made a good choice by running with a boat from a sailtraining establishment that was presumably rated and equipped for ocean sailing. Possibly they were ex customers who were looking to increase their experience in the safest and most responsible way possible by sailing in the schools' boats on a school organised crossing?

    Does anyone know the rating for the CheekiRafiki? Did it have a category A rating? Boats with this type of build quality should be limited to round the cans racing where rescue boats are close to hand.
     
  2. RHP
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    RHP Senior Member

    I find it extremely disappointing that boat builders commission boats to the social needs of their clients - ie marina based fair weather sailors as opposed to building a sea worthy craft capable of getting a typical family crew safely home if surprised by a inclement weather. Yachting magazines when testing a boat always give it a glowing report regardless of the unsuitability or poor sea keeping characteristics of a yachtnor do they advise the practical use of the boat. They dare not risk losing the advertising revenue.

    Nor do they have the courage to compare the seaworthiness of the latest mass produced throwaway against a historic design like a Rival 41, Nicholson 35 or Twister 28, but prefer to focus on king size, centre line berth, a kitchen bigger than the one at home and massive beam without mentioning the lack of handholds or bars to break your fall in a rough sea.

    Designers are at fault for their modern marina caravans and the modern media is at fault for not pointing out these failings to their readership.

    There endeth the lesson, all rise.

    PS Lets not pretend a Cat A rating means anything......
     
  3. Dick Flower
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    Dick Flower Junior Member

    With reference to the picture of the keel nut and stud arrangement posted above, and various references made here and on other strings, it seems that the keel studs, nuts, and (rather flimsy) backing plates are stainless steel of some sort.

    Maybe I am out of date, but I have always understood that stainless steel, even "marine" grades, should never be used for fastenings below the waterline.

    The fact that there are obvious rust marks around the fastenings (and probably more extensive marks have been cleaned away), is an indication that there is water ingress around the fastenings, suggesting a loss of integrity of the sealant between the hull and the keel, or even slightly loose fastenings.

    If that boat were my responsibilty I would consider lowering the keel at the first opportunity to examine the studs, and in the meantime at least remove, clean, lubricate and replace the nuts and washers etc., one by one, re-torqueing the nuts to the builder's specification, then clean around them carefully, and monitor for any water seepage.
     
  4. JosephT
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    JosephT Senior Member

  5. Doug Lord
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    Doug Lord Flight Ready

  6. Nick.K
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    Nick.K Senior Member

    Thanks for those interesting links..
    One thing that puzzles me about keel issues is the general lack of concern. I´m sure many would disagree, but this is a problem that has been going on since the fin keel became fashionable and yet pretty obvious measures such as increasing the root area, incorporating flexible elements to prevent total loss, attaching the keel to internal structure not the hull skin or provision of internal ballast for reserve stability....these have not become standard features and significantly, the public go on buying family cruisers that have little margin of safety. These discussions have focused on keel failures while at sea, but major damage due to grounding is very common on fin keel yachts and also a result of the design.
    I don´t think it is useful to look at the number of failures per quantity of boats, many boats are only used for a few weeks a year while others such as CheekiRafiki may be in practical full time commission. The only conclusion you can draw is that it is safer to stay in the marina!
    Has anyone ever heard of a Folkboat keel falling off? I helped to remove one in the yard where I work, the bolts were wasted to about a third of their width but it still took a few hours of sledge hammers and wedges to get it off and that was with the ballast in the air hanging off the bolts.
     
  7. RHP
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    RHP Senior Member

    This is the point I was trying to draw peoples' attention to as well Nick. It shouldn't happen unless designers and builders are cutting corners (costs).
     
  8. MikeJohns
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    MikeJohns Senior Member

    I suspect that this is a classic case of the keel interface being designed on the inadequate ABS ORY 1986 scantling rules for GRP. They were inadequate and were corrected in 1994. Unfortunately a lot of designers were ( and some still are) ignorant of this and kept using cored layups, laminate schedules and attachment methods that were beefed up considerably in the 1994 release. The loads were initially considerably underestimated for the keel attachment and accumulated fatigue damage lead to a high number of failures. Unfortunately by the time the 40.7 was in production ( 1997) the new rules were published and circulated but the design, while claiming ABS compliance, doesn't comply with the the ABS rules in force at the time of production.

    ABS OSRY in 1994 added the following requirements:
    If the hull is cored in way of the attachment then a stiffer core should be used and both laminates beefed up, and the keel bolts should connect structurally through to the floors or girders in some way. Otherwise for simple backing plates, as illustrated, the laminate should be a solid layup in way of the keel and as a quick ready guide, at least as thick as the keel bolt diameter, and no core. The heavier layup should run along to at least the mast base.

    Any craft designed to minimum ABS ORY scantlings for GRP prior to the 1994 release should be modified. Even for sheltered water. And certainly isn't designed for the dynamic loads of offshore use. Unfortunately this boat clearly falls into this category. It's also not the first time someone has died in this particular model from a keel breaking away. Nor will it be the last unless people get the message.
     
  9. Nick.K
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    Nick.K Senior Member

    Mike, are you saying that the 40.7 is cored in the area of the keel attachment?

    In the case of a boat that did not comply with the design rules in force at the time of production and where there are multiple failures surely the manufacturer should have a duty of honor if nothing else to publicise the issue and the appropriate modifications.
     
  10. CT 249
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    CT 249 Senior Member

    I'll be one of those who disagree.

    There were many, many thousands of fin keel boats that sailed the oceans of the world and yet the loss of keels was almost unknown until about '85, when fin keel roots started to generally become smaller.

    Try to find an instance of a lost fin keel in a boat designed before the late '70s or 1980s. I can find mention of only one in my very extensive library; the 30 foot Van de Stadt design "Pioneer", which was struck by a whale in the '71 Cape to Rio. She took 20 minutes to sink and the crew got the time to get into a raft and be found by a freighter well of its course. It appears from the name and LOA that this boat would have been one of the many hundreds of Pioneer 9s that were made. Matuku was also lost after a whale strike between NZ and Australia around December '67, but I don't know if she suffered keel damage. Snow White was lost after a while strike between Suva and NZ in 1979 but since we know that whale strikes can sink conventional cruising boats (as people like the Baileys found out) whether these issues are an example of a "problem" with fin keelers is very much open to debate.

    So known cases of sinking due to keel loss in the early fin keel days were rare - just one, and that was due to a whale. It also appears that even if the crewed offshore racing boats that vanished without trace are ascribed to fin keel problems, there is still zero evidence of a significant problem. The number of crewed offshore racing monohull yachts designed before '77 that vanished on deliveries or races was minute. There were two in an early '50s race in NZ (Wellington-Christchurch); the Mauric one tonner Airel in the 'Med about '76; the Spencer design Sequoiah (?) between Hobart and NZ about '84 (?); and the heavy displacement Finnisterre-style S&S "Revenoc" off the east coast of the USA in the late '50s.



    That's about all I can find any info about, from searches in my extensive library and on-line databases, plus going through just about every mag in the national maritime museum library. Sure, some may have been missed but the losses that did occur were quite well publicised so there is no reason to think that many other fin keel offshore racers vanished without trace, nor that their losses were due to keel loss.

    Only two of the boats that vanished (Sequoiah and Airel) were fin keelers; the two boats in the Christchurch race would almost certainly have been long keelers; Revenoc was a keel/centreboarder. While this is a very scanty database, it certainly does NOT show that losing fins was a significant problem or that they are more dangerous that other types. I know of at least one full-keel boat, to a design and builder that has a good popular reputation. that suffered major cracking around much of the bilge area around the full keel, so it's not as if they are immune to such issues.

    The facts appear to be that keel loss was basically unknown in the days of bigger fin keels, as were used in S&S/Carter/Peterson/Holland type boats and by people such as Farr until about '78. Given that the boom in offshore racing peaked in the "early to mid fin keel" era ('70s to mid '80s), it appears that the loss rate of fin keel boats was dramatically LOWER than that of earlier eras.

    None of the above should be read as saying that we have not had a problem in more recent years - IMHO the current loss of keels (especially in canters) is ridiculous and rating rules (which are fairly easy to change) should be changed to ensure that solutions, which could perhaps be as easy as longer keel roots, are found.
     
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  11. CT 249
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    CT 249 Senior Member

    What was the other 40.7 in which a keel loss caused a fatality??
     
  12. Nick.K
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    Nick.K Senior Member

    You are right, the issue is to do with reduction of root area (etc) not the fin keel generally. I meant that many would disagree that there is a general lack of concern. You don't have to be an engineer or boatbuilder to look at the attachment method of deep narrow fins such as on the 40.7 and feel concerned
    ...yet people go on buying and sailing them.

    What in your opinion was the failure mode of the CheekiRafiki? Was it cored in the attachment area? I can't find any information on this but if you look carefully at the hull photo you can just about make out an inner and outer skin.
    A core would also be consistent with the large flap of laminate torn off one side.
     
  13. powerabout
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    powerabout Senior Member

    I think CE need to step in and possibly look at having a tether attached so the boat will stay upright for a short while ( still sinking) considering the devastating failure mode that you probably cannot build out when hitting a large object at speed?
    just a thought, might also be a retro fit as well?
     
  14. farjoe
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    farjoe Senior Member

    Bolt Torque

    Some comments were raised in some forums re the effect that correct torqueing may have on the the keel bolts.

    Beyond torqueing to the point that the keel does not move about to avoid cyclic issues, wouldn't torqueing reduce safety margin available to a particular bolt?

    To put some numbers to it, let us say a bolt yields at about 100 units and it is pretorqued to 40 units, would your safety margin now be limited to only 60 units?
     

  15. Dick Flower
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    Dick Flower Junior Member

    Using that logic, maybe it would be best to have the nuts finger tight:)
     
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