Keels and Keels Again!

Unfortunately for you Peter, most people would rather go to sea in an insurable boat.

You keep promoting your 'method', knowing that its has not been subject to engineering specifications, not been designed or certified by industry accredited NA's and thus not able to be insured.

Have you actually sold any boats using your design in thirty years, and if so do you have any professional indemnity cover?

 

Excerpts from PROSS's posts at Sailnet forums:

".....I was hired to build a 32 ft sport boat in '99. It grew for many reasons. Too much detail for this post.
I built the prototype hull and tooling. Hull#1 is the boat mentioned at the Annapolis Boat Show. No liners, all structure and built to race in the Bermuda 1-2.
These are build details as I understand them: The production boats "may" have eliminated the extensive structure and replaced it with liners. They are a combination of Vinylester and epoxy resins in a single hull laminate. Some are cored some are not.

Shots of the boat before the repair....the footprint of the keel tooled from the prototype:

(Set of images downwards here attached)

Other points of interest:
WHAT is that shim? Is it a spacer?
That keel looks to be attatched, but has gone through some extensive movement.
Footprint appears to be less the "as built" by nearly half.
What is that brown goo running down the keel?
Sure looks like that keel rotated back and forth on that shim/spacer, since the shim/spacer seems to have a RADIUS!
Prototype had no keel sump to allow for limited, uninterupted, continuous fibers. After sailing with the owner on his other boat, I built a 9 in solid glass plank from stem to stern. The entire stem is several inches of solid glass, certainly more effort than production would allow.
After completing the tooling, I removed the protoype from the mold and the deck mold off the deck plug. I had given CFYW a year to complete the first hull and tooling. I refused to build the deck and moved on to my next project. I saw the first race version in their shop in '03 and had a fit, they called it lobbing grenades. That slab keel was designed (was told my designer and company owner) to make for easy draft changes............Mars wouldn't need to build several plugs! One very very deep plug, just stuck in the sand at different depths.........................
IF the production boat had eliminated structure for liner, reduced floor heights for headroom AND reduced the bonding/bolting surfaces on a deeper heavier keel............................"

And afterwards he says:

"That shim is the weak link here, imho. That keel wagged back and forth and simply snapped those bolts from friction. Just imagine all the forces on those boats in a normal seaway, boat responding to puffs, chop etc. Compression, tension, and massive heat from the wagging friction. Only a guess, but I would say the grounding and following repair had only added to the failure and was not the reason for the failure.
Ever snap off an extra long bolt with vise grips? If the nut is tight enough, the bolt snaps at the nut. Not enough torque and the bolt breaks on the WRONG side of that nut. That is my feeling here, even IF they had checked the bolts prior to leaving the dock ( as I posted elsewhere, checking bolts prior to departure is no different than checking tire pressure before a long road trip) that keel was going to wag itself off.
That shim APPEARS to be there because the top of the keel seems to be a "waterline" plane, while the hull had some rocker and an apparent different plane with respect to the top of that keel. The boat I saw in their shop certainly had the beyond plumb look to it as well, but I saw no shim there.
Density is going to be another issue, the density of that shim vs lead keel and solid laminated hull above. I doubt the lack of core had anything whatsoever to do with this failure."


From the Houston Chronicle about Bruce Marek:

"Bruce Marek, a well-known naval architect who designed the boat for Cape Fear Yacht Works, said the company was never directly notified of the damage, which may have been extensive, or asked to look at the boat or participate in repairs. Texas A&M-Galveston, which had been given two Cape Fear 38s for its sailing team, paid $1,862.21 to Payco Marine to repair and reattach the keel of the Cynthia Woods.

Marek said he could not tell from the photos, which quickly made their way to various Internet sailing sites, exactly how much damage was done.

"We're analyzing it," Marek said. "We will have some other naval architects take a look at this also, so I don't want to say anything until we have a chance to look at it, put a measurement to it and see what that is actually showing. Just by looking, you can't say this is what it means.""


Now I've learned there were backing plates not wider than keel width, 5/8" thickness on the fiberglass, there was not a sump, $1,862.21 were paid to repair and reattach the keel after grounding(s), builder and/or designer not being contacted. Also learned the original keel foot print was bigger than mounted keel, and there was a shim or spacer between keel and hull. Would like also to know facts about supporting structure.

Thanks for your excuses Paul B.

Cheers.

 

Excuses? I've given no excuses for anything. I have mentioned the FACTS about how this type of keel attachment is not some abnormal arrangement. Funny, you claim to be a professional yet you don't seem to know these things. Have you ever designed a keel attachement for a fin keel during you studies or professional career?


Actually, you have not learned some of the things you claim. There is no documentation about the laminate, just an estimate by an unknown someone who took no measurements. You publish things as fact that you have no direct knowledge of. Rumour mongering is not very professional.

I doubt you've seen any documentation about what was billed for the repair after grounding, or what was done.

As far as we know the keel footprint of this boat was the one designed for it. The chord length is not something that is particularly small compared to other modern designs.

The witness line on the hull is from the prototype hull that the mold was splashed from, and actually shows pretty poor moldmaking technique.

I have seen other boats with spacers added between the keel and hull. I don't particularly like the practice, but in this instance it did not cause the bolts to snap as Mr. Ross suggests. Are you aware that some fin keels have had spacers in the past?

One thing that immediately springs to mind is people like you often claim that in a grounding the aft edge of the fin keel will push up into the hull. In this case it did not.

It is sad that someone would jump on a tragic incident and try to make hay for your own warped point of view.

If you are going to present youraelf as a professional you should try acting like one. Maybe then you would have more success and not have to work for short money.

Cheers, or not.

 

Oh! You really do want to dance with me, Paulie Bee....! How charming!
I'm wondering: Do you use your brains while posting? Or just your guts?
I love you. Kisses.
Willie Boy.

 

Offical news from Texas A&M can be found here:

http://tamus.edu/offices/communications/cynthiawoods/index.html

Press access to hull and keel for photos this afternoon (27 Jun).

Earl

Later: keel photo here

http://tamus.edu/offices/communications/cynthiawoods/images/keel2.JPG

 

Thank you, Earl.
A pity documents and images take such a long time to download (they are huge!). To save other members' time, I post here the image from the keel in a more manegeable size.
I'm wondering about that notorious oxidization and apparently bent washer-plate at the forward bolt.

Cheers.

 

Guillermo


I don't like these sorts of attachments, When you consider the stress paths when the boat is heeled this is very poor engineering. There is such a high stress being taken on the skin alone which is carrying the entire moment in shear and almost entirely by the skin adjacent to the outer edges of the widest backing plate. If anything's compromised you are cactus. Nothing stops the keel breaking completely and cleanly away.

 

Here's the attachment area at the original resolution, with edge enhancement applied.

Earl

 

When you consider more than 90% of fin keels bolted to composite boats have been done this way since the 1960s it is a wonder we haven't had a keel a day fall off, according to your opinion.

It is very easy to say you don't like it, but can you tell us specifically how you would do it?

 

Imho, that is a relative no brainer.
Spread the load athwartship over a greater area.
By a floor or structural grid so lateral moment from the keel is 1/3 of total moment byway of athwartship members. (My amateur rule of thumb)
Those plates point load to their edges;hence the failure there.The plates
should transferr the load to the floors/grid properly.-

 

Its been interesting to hear the last few analysis's. When I first looked at the pictures I was tempted to express similar opinions, but abandoned my message because I thought it couldnt possibly be that obvious. But, it is that bleeding obvious. That the hull 'skin' has just been ripped off at the backing plates like opening a can of sardines.
Roly's comments on having some sort of 'athwartship' members is right on the money.
The technique in the pictures is like mounting the engine block straight onto the skin, and not use any bearers. And the weight of the keel is bigger than any engine block.
Yes, it is a wonder we havn't had a keel a day if this is standard mounting practice. No manner of complex calculations from qualified engineers is going to cover this blatant example of really poor construction ( I wont say design, because any forethought is blatently lacking)

 

You are both missing the obvious. There ARE athwartships floors in this type of design. The areas between the metal plates would have floors running port-starboard, and forwarsd and aft of the metal plates as well.

In this instance it appears the bonds of those floors was broken, which allowed the resulting unsupported hull panel to become greater in area. This surely led to panting, delam, and failure.

Whether the broken bonds of the floors was due to poor design, workmanship, or prior groundings is unknown at this time. At least it is unknown to me.

I still have not heard a detailed comment on how anyone on this forum would improve this design. Simply saying "spread the load" isn't detailed. If someone asked me how to become rich and I told them to "make lots of money" that wouldn't be very helpful.

 

"I still have not heard a detailed comment on how anyone on this forum would improve this design."
I am not a pro designer/builder but...
there are many ways to spread load.- Continuous floors across sump with keel bolts thru floor members,with athwartship rectangular plates. (no gap between floor and keelson laminate.)
Fully encased Hotdipped galv. steel floorgrid to WL. as in X-yachts for instance. Not saying its ideal (galv, steel) or fits the parameters for a ULDB, but I don't recall a X-yacht's keels pulling their mounting washers thru the hull.
Or +50% the current keelson laminate thickness (kevlar) feathering over core & a one piece washer system the shape of the keel mount stem, on the "cynthia woods", may have been enough to prevent this.
The area of the washers and the thickness of the keelson laminate in this case,imo, enabled this failure. Just how far does one push light weight?
Imo, the keel bolts should be directly thru a continuous floor/grid. Not a marginal hull thickening.

 

OK, good ideas, a good start. Let's think some more:

I have seen ONE attempt to put the bolts through a laminated hat section floor. The result was the boat coming back to the yard after less than an hour with the keel separated from the hull enough to see through.

You would have to make the floors thick enough/strong enough to support the plates/washers/nuts. Look at the scantling required. If you think the hull can't be made strong enough for this task how will a laminated floor be made strong enough?

Two issues.

First, bonding the grid into the structure. How will you do that?

Second, even galvanized steel will be unhappy in the bilge. How can you repair/rework something that is bonded into the structure?

On this boat there was no core, but let's look at your idea anway.

I have seen very successful assemblies produced that had a solid keel laminate built up so it was nearly as thick as the adjacent cored panels.

You still would not have a one pc plate, since even with the thick laminate you still need to have adequate floors to support the load.

Since I don't know the thickness of the laminate I would assume you don't either, so until we know we should not pass judegement.

See the above comment regarding your idea to bolt through a grid.


Now let's get even more involved. Consider a vast majority of non-racing boats have their external keels bolted not to a flat laminate but into a sump, usually a good foot below the rest of the hull.

How will you have a grid for that?

How would you bolt up through floors that traverse the sump? How would you make that strong enough?

You won't be able to make plates extend beyond the keel footprint, since they are actually inside the keel (sump) footprint.


I spent the day sailing on a boat that is about 15 years old and has a smaller footprint for the weight/lever arm than the boat we have been discussing. Neither that boat, nor any of her sisterships, have ever had a keel issue. These boats have been sailed hard over the years in up to 30+ knots and big seas. Based on some opinions that should not be possible. It only blew in the low 20s today, so maybe we were lucky.

I'll be out again tomorrow to see if we can hold our lead in the regatta against a fleet of boats that probably have very similar constructions.

 

my 2 cents

poor engineering

even a beginner NA could do better than that