When was that design standard made? Are we talking about boats that were built in the 60's/70's or boats that are being built in the 90's/2000's?
That comes from the American Bureau of Shipping Guide to Building and Classifying Offshore Racing Yachts from 1994.
Specifically, Section 7.3 for hull plating of FRP boats:
Quote:
The bottom shell thickness is to be increased for the extent shown, and using the design heads given on Figures 7.1 and 7.2. In addition, the thickness of the bottom shell extending over the length of the keel attachment to points 50 mm (2 in) forward and aft of the forward and aft keel bolts, respectively, and 50mm (2 in) outboard of the bolts is not to be less than the diameter of the keel bolts. Bidirectional laminates are in general to be used, Bi-directional laminates arc to be used also in way of local reinforcements for chain plate and other load-carrying fittings. Care is to be taken to provide a gradual transition in fiber reinforcement between hi-directional and uni-directional laminates to avoid abrupt changes in strength and stiffness.
(emphasis added)
ABS got out of the business of classifying yachts in 1996 since ISO was developing international standards for yachts, so the 1994 version is the newest there will be.
Contrary to what that lawyer said, ABS Guide for Offshore Racing Yachts was never a "national standard" with any effect in law. It's primary application was to qualify a boat's construction for entry into International Sailing Federation sanctioned off-shore races.
The replacement ISO standard works from first principles, so it won't have a blanket statement that the hull thickness must equal the bolt diameter.
I am no yacht designer or naval architect or engineer, but I am familiar with the law, and I suspect something like the ABS Guide will very much "have an effect in law." The standard for a negligence case would be that the defendant acted as "reasonable person"; in a product liability case there is normally strict liability for the manufacturer, even if he was not negligent, if it was not manufactured in accordance with the design, or if the design or instructions (or their absence) resulted in the injury. Thus, if the design significantly varied from what was generally accepted practice, the manufacturer and/or designer will have little defense. And a book like the ABS Guide for Offshore racing yachts will be the kind of thing the plaintiffs will introduce in evidence to show the standard or practice in the industry.
From the photos that I saw, the thickness of the hull well exceeded the diameter of both the larger and smaller bolts and the laminate was clearly biaxial glass. That thickness seemed to extend all the way to the longitudinal stringers and far (several feet) fore and aft into the hull. I am not certain what the A&M expert was referring to when he says they were concerned about a 1/2" layer, but I am wondering if he is referring to the tear line seen in the closeup photos.
As to liability, I suspect that liability will ultimately be assigned appropriately, but at this point nothing in the statements make it clear to me whether or not the liability lies with the designer, builder, repair yard or repair manager, or all or none of the above.
The article indicates that 1.5" keelbolts were used. Maybe you saw some better photos, but in the ones I've seen the lay-up did not appear even half that thick. However, I went back and saw in your post #48 that you opined the thickness approached 1". I'll defer to your more experienced eye. Still, the ABS standard (per Gramp34) would call for laminate thickness 50% greater than the one seemingly used.
Quote:
I can only compare it to what I know on my own 38 footer. If I remember correctly, the original drawings on my boat refer to a 48 mm thickness in this area, roughly 1 7/8". There was a disaster with a custom built and poorly re-engineered version of my boat that was converted to an IMS style bulb keel. That boat had roughly 7mm at the keel bolts and the Australian NSW Coroner's report indicated that roughly 19mm was required to acheive a safety factor of 2 in sheer. Eyeing the photo the CF38 the thickness could easily have been an inch (25mm) or more of glass.
So if I design a keel attachment with twice as many 1/2" bolts I only need a 1/2" thick hull That standard does not make sense in its own context. If there were requirements for the number and size of fasteners for a particular keel weight and lever arm length; then maybe a corresponding hull thickness could be associated with the keel bolts; but again that goes back to hull design. If the standard was developed in the early 90's and the boat was built in the late 90's the standard which they are quoting may well be obsolete; and a newer design standard may have been in place.
We don't know what standard or modeling was used to design the hull. Certainly some standard and/or FEA model would have been used so we just have to wait to find out how the boat was engineered. Let me also remind everyone that we have not seen a large number of Cape Fear 38's failing at the keel stub so that tends to negate the issue of design strength (unless this truly is the first boat to fail from cyclic fatigue and others are getting close to failure).
I also hate to say this but in terms of liability; I have a hard time understanding why people should be suing mfr's of pleasure craft when they are putting their lives at risk by setting out to sea in a 38' boat on an ocean crossing race. Keel failures happen all the time on racing maxis and people do die while racing their boats inland or offshore. It is a tragic loss and I do hope that it was just an accident and that there was no negligence on the part of the mfr or the people who tried to repair the prior damage; but somehow I think someone will be blamed for the death of Roger Stone. I hope that the aftermath of this does not cause Texas
A&M and all of the other major schools to shut down their racing sailing programs (for liability concerns).
So if I design a keel attachment with twice as many 1/2" bolts I only need a 1/2" thick hull That standard does not make sense in its own context. If there were requirements for the number and size of fasteners for a particular keel weight and lever arm length; then maybe a corresponding hull thickness could be associated with the keel bolts; but again that goes back to hull design.
You're right on with this. The ABS Guide has calculations for both heeling loads and grounding loads. The designer specifies the number of bolts and where they're located, and the ABS formulas give the minimum diameter. So more bolts = smaller diameter = thinner laminate.
The guide is online at ABS Downloads (you might have to register to get there).
Quote:
If the standard was developed in the early 90's and the boat was built in the late 90's the standard which they are quoting may well be obsolete; and a newer design standard may have been in place.
Right on, again. I think the Cynthia Woods was built in 2006. The International Sailing Federation Offshore Special Regulations then said:
3.03 Hull Construction Standards (Scantlings)
A yacht defined in the table above shall have been designed and built in accordance with either:
a) the EC Recreational Craft Directive for Category A (having obtained the CE mark), or
b) the ABS Guide for Building and Classing Offshore Yachts in which case the yacht shall have on board either a certificate of plan approval issued by ABS, or written statements signed by the designer and builder which confirm that they have respectively designed and built the yacht in accordance with the ABS Guide,
c) except that a race organizer or class rules may accept other evidence of suitability of design and build when that described in (a) or (b) above is not available, provided that the requirements of (a) or (b) have never been refused due to unsuitability of the boat.
The EC Recreational Craft Directive uses the ISO standards that directly calculate the strengths and stresses on the parts.
Given that the Cynthia Woods had large bearing plates under the keel nuts rather than just washers (called for by the ABS Guide), I expect the boat was designed to the ISO standard, not the ABS Guide.
It is my understanding that the bolts were a mix of a single 7/8" bolt and smaller 5/8" bolts. i don't know whether my recollection or the 1 1/2" diameter comment is faulty. The two measured hull section photos seem to show an inch of laminate. In the end it will come down to the real engineering. Simple rules of thumb can't apply when you deal with the high loadings of a keel like this one. Clearly efforts were made to deal with the high loads, but ultimately the enquiry will examine that closely.
Just got my Sept? Sail mag in the mail, and lo and behold is a 2'ish page article on keeping keels on boats, and THIS story is part of that article. ALtho not too detailed persay, nor any new insites etc, other than to say, that the CG will have results at some point in time. page 76 IIRC
Marty
__________________
She drives me boat,
I drives me dinghy!
Dobroth was a fairly well known designer many years back in the heyday of Tripp, Reichel, Schlageter. He did some nice work too but is kind of a "has been". I've heard substance abuse.
He's a tough guy to like- a know it all, one upper, arrogant to the top.
Maybe this A&M thing will jump start his career. Saw him at the Jags this year. Got himself a drop-dead gorgeous trophy wife. How did THAT happen?
Good for him. Maybe he'll make a comeback. They live in Connecticut.
Anybody know Brendan Dobroth? He apparently is on board with Texas A&M in some capacity for the investigation.
That standard does not make sense in its own context. If there were requirements for the number and size of fasteners for a particular keel weight and lever arm length; then maybe a corresponding hull thickness could be associated with the keel bolts; but again that goes back to hull design. If the standard was developed in the early 90's and the boat was built in the late 90's the standard which they are quoting may well be obsolete; and a newer design standard may have been in place.
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