Keels and Keels Again!

Hello Paul, good to see you up to your usual level of diatribe.

You may note that its a rhetorical question open to discussion which was what I wanted.
I was hoping for a more convivial engineering discussion rather than the chest beating that occurs.
So how about discussing this from an engineering point of view rather than a meta-analysis of other peoples opinions.
The laminate schedules are there to see. The design lacks compliance with the very regulations it was supposed to meet and as pointed out in those reports subsequent people working on the boat simply presume the designer knew what he/she was doing. In this case it's quite clear that the designer who so ever that was did not know how to comply with ABS OSRY.

As for levelling allegations the allegation is there in the report. Or do you think Dobroth's report vindicates the design ?

We can for example say (following an officail enquiry) that the designer of the Maxfun35 casued a death by confusing basic engineering principles and ending up with a FOS of 1. In this csae the design ended up with a FOS of 1/3. Failure was as Dobroth showed inevitable. Someone is responsible for the design and unless Marek clears himself (as he can so easily do ) it's his reputation that's hurt even if someone else re-designed it.

The USCG report is sadly lacking, in fact it's an abysmal report, why is that did they simply presume it met ABS and therefore the failure was due to something else ?

The boat is a human artifact it has a designer, the design was deficient. Whether that designer was the original or the subsequent one and who that individual is, may yet be revealed.

Someone died yet again becasue of poor design practices. As they will continue to do until the message gets through to all those involved the racing industry, and what is so abysmal is that the knowledge and the failures are there for all to see, people just need to wake up. All the smoke and mirrors is trying and obfuscate the fact that these sorts of deficient keel attachment should not happen.

If you disagree then show me any resonable engineering approcah and we'll work through it.

 

No, they are not.

What regulations was it "supposed to meet"?

What is this "racing industry"? This isn't a race boat being discussed.



Just like your comments about the Syd-Hobart issue, you only want to see things that bolster your point of view. Lies of omission are still lies.

No matter how much mud you throw you will still be a failure.

 

Page 1: "... inadequate design and construction ..."
Page 2: "Significantly the vessel failed five design requirements ..."
Page 2 : "... and confirmed the inadequancy of the design ..."
Page 15: " ... concluded that the vessel failed the following five criteria ..."
Page 16: " ... confirmed these design and construction deficiencies ..."

There are several more references in the report to design and/or construction shortcomings but you get the idea. Paul, I don't see how you can sustain your statement: if you mean the report is a pack of lies then please say so, but if that is what you meant you should also identify the specific lie(s) to permit further discussion.

It is not difficult to perform the simple calculations to support the report's oft-stated conclusions: the best one can do for it is to show it is merely marginal. It might have survived gentle cruising under flat-water conditions for many more years. The report deals with purely static loads; I would expect it to encounter rather greater loads under the dynamic racing conditions for which it was supposedly intended *. This, of course, assumes the boat was built as designed: this expectation is supported by the fact that the sister vessel appears to have identical construction, but in the absence of design documentation it is not proven. The designer's best defense seems clear -but he hasn't taken it as far as I know- which is to provide the relevant drawings.

* later correction: if this is the same design, Marek himself describes it as a racing cruiser

I cannot see how the school can be liable except perhaps to a minor degree related to maintenance and operating practices. If they are indeed liable, then so is every owner of a car whose exploding gas tank, inadequate safety harnesses, failed air bag etc. has resulted in a death, because the owner failed to get it certified by a qualified individual. The user of every dangerous appliance, vehicle, building, substance, boat or whatever is likewise liable for the consequences of its use. The designers and builders go scot free because the user and purchaser should have known better.

AH: I did all that, except for the bit about Class rules which I don't have info about: I imagine that has everything to do with fair practice for racing purposes and maybe nothing to do with safety, but I could be wrong. The question I asked has to do with your second item, the load paths. The most obvious one, namely the frames, seems to have been avoided. The worst one, direct to the unreinforced skin, seems to have been selected. The question remains - why?

Rick: good to see both sides of this argument. There is little substance and a lot of opinion in the summary of the the Coastguard report that you provided so it is hard to deal with at an engineering level. In the scuttlebutt extract it is interesting to note doubts on the design of the keel attachment by both the builder of the prototype and the owner of the company that repaired the keel. I could not get the link (http://www.chron.com/disp.story.mpl/metropolitan/5837037.html) for the full story to work, probably out of date by now.

On the liability issue you raised earlier, yes this is a publicly visible forum, but comments and reasonable conclusions based on the contents of publicly released documents are unlikely to be actionable. Postings that contain mere statements of opinion unsupported by analysis, data or quotations from publicly available documents, on the other hand, might well be.

 

Terry
I tried to find the full USCG report but could not. I wanted to see what ground it explored. I thought it had been posted somewhere.

Those who jump to the conclusion on designer negligence from the Texas A&M report are also making conclusions about the competence of the USCG and their expert, Villalon. I am not so inclined to vilify respected individuals by considering only one side of the story.

Your other question regarding the apparent ring beams in the attached photo is just that I suspect. They are "apparent" beams. They are likely to be hollow or very low strength filler glassed over. Their purpose it to spread the local stress from the keel support into the main hull structure. They probably thin to nothing as they extend transversely so nothing like a full ring beam. If the keel bolts bolted through these they would just compress I expect. This type of joint is highly dependent on the compressive strength of the hull material and preload on the bolts. If the joint opens up due to loss of preload then the bolts are put into bending and they will fail in this mode.

Again I am surmising here based on what I have seen before without having any detail. If they were solid ring beams, made from high compressive strength material then they would likely produce a better keel connection than what was done here.

Rick W

 

Terry
I tried to find the full USCG report but could not. I wanted to see what ground it explored. I thought it had been posted somewhere.

Those who jump to the conclusion on designer negligence from the Texas A&M report are also making conclusions about the competence of the USCG and their expert, Villalon. I am not so inclined to vilify respected individuals by considering only one side of the story.

Your other question regarding the apparent ring beams in the attached photo is just that I suspect. They are "apparent" beams. They are likely to be hollow or very low strength filler glassed over. Their purpose it to spread the local stress from the keel support into the main hull structure. They probably thin to nothing as they extend transversely so nothing like a full ring beam. If the keel bolts bolted through these they would just compress I expect. This type of joint is highly dependent on the compressive strength of the hull material and preload on the bolts. If the joint opens up due to loss of preload then the bolts are put into bending and they will fail in this mode.

Again I am surmising here based on what I have seen before without having any detail. If they were solid ring beams, made from high compressive strength material then they would likely produce a better keel connection than what was done here.

Rick W

 

More on Cape Fear 38R. From their press site.

Rick W

 

"...Those who jump to the conclusion on designer negligence.."

you mean like:
"..They are "apparent" beams. They are likely..."
"..They probably thin to nothing.."
"..If the keel bolts.."

You mean this type of 'jumping' to conclusions/assumptions?

"..If the joint opens up due to loss of preload then the bolts are put into bending and they will fail in this mode..."
No, the bolts would fail in tension.

But, as you say
Again I am surmising here based on what I have seen before without having any detail..."...so how can you make such statements like above with the detail, in the same way you accuse others, which are based upon the facts within the report?

"..They are "apparent" beams. They are likely to be hollow or very low strength filler glassed over...They probably thin to nothing as they extend transversely so nothing like a full ring beam."

You know this how, where does the report state this?

Really don't understand what you're driving at...those who do not understand or do structural design seem to the ones making "wild accusations".

 

apart from the ongong legal arguments
I really am puzzled as to why--- the brightest engineers on this site are trying to sort this thing in their minds
TO me, there seems that there can be nothing that can be mechanically A GIVEN, all those plastics , ply, glue, etc, how on earth can you keep control, quantify, access?
I mean unless each and every one is stood over as ie the build of that yacht(biggest composite) built for the ex owner of Avis, then how on earth can you warrent ?

In times gone by, wooden yachts, were built by feel, a feeling from lifetimes work

IMO you can never analyse in depth, why this thing, and it is a thing, anything built in grp is a thing, never a she, failed
Your pics RIC/ show matchwood
Also you guys with eng degrees
start to listen to US
The main failings of people (in charge) is the failure to listen
Ad Zilch is a prime example

 

A.K.
"..The question I asked has to do with your second item, the load paths. The most obvious one, namely the frames, seems to have been avoided. The worst one, direct to the unreinforced skin, seems to have been selected. The question remains - why.."

It is next to impossible to find this out without the construction dwgs. Since the authors of the report were unable to obtain these (one wonders why?), as such it is just pure speculation. BUT, very important!

One can never under estaimte load paths or in many cases, lack of!

 

This particular quote makes me wonder if this more common in the near future..
"Bruce Marek, an experienced naval architect who is responsible for the Cynthia Woods' design, said the vessel's structure is not flawed. Marek said he uses the design of the boat, a Cape Fear 38, as a textbook example of a model design at industry seminars and when teaching naval architecture review courses"

 

Stu
There is nothing inherently unsuitable about composites.

You probably take for granted the effort that goes into producing a shiny piece of Al alloy. It does not achieve its usual consistency by any inherent virtue. I see it a few times a year when I visit mines, refineries and smelters that all play a part in providing you that shiny piece of aluminium. In fact I believe you check any batch you get to ensure it is what you ordered.

You may also take for granted the skills that you have developed over years of learning your trade. A shiny sheet of aluminium can quickly be turned to scrap through poor design and or poor construction. Every second piece I weld becomes scrap.

The materials that go into composite boats have good quality control just like aluminium. Many are used in the aircraft industry and very tightly controlled. The reputable constructors will have experienced craftsmen and good quality control. There is a whole range of test procedures for composite construction just as there is for any welding.

So I do not see any inherent difference between composite and aluminium. In fact it was poor control over workmanship with aluminium that was determined to be the root cause for the Excalibur drownings.

I would prefer to be on a Cape Fear 38R than on Tin Can (see attached). As someone else pointed out though I would not want my life line secured to the keel mounting bolts on the 38R.

By the way there is a reference to the USCG Cynthia Woods report back on page 12 of this thread but the report has been removed.

Rick W

 

my dear chap
my point being(mostly) academics and leading hands on, should heads together
too late cette nuit, la vin rouge, )

 

For me as well.

 

It should be a public document so someone in the US might get a copy?

 

Teddy
The link is posted on a few places around the web but it is now dead. I wonder if anyone downloaded a copy. It will come under greater scrutiny now.

Rick W