Keels and Keels Again!

Mike

The point of my original post was some measure of defence for the butt to plate joint. On first impression it is an awful connection but I have seen that it can work reliably if designed properly for identical isotropic materials. Only constraint is to have enough initial pre-load to prevent the joint from opening up.

The other point was that a butt joint is likely to behave quite differently to a joint that has a recess or stub. I am only surmising the behavior. I would like to see proper analysis of this.

These points were made to progress the discussion. It is a pity you cannot do an analysis with anisotropic materials (if you were inclined to put in the effort for all our education).

The other matter you have raised in early posts with regard to regulation is something that had my thoughts ebbing and flowing on how much is good. This is a significant issue that probably deserves its own thread.

Rick W

 

think it all boils down to cheap, cheap
IT IS NOT SO HARD TO BUILD RING FRAMES OF ALLOY INTO ANY BOAT,and from there fabricate a structure whereby the keel can be bolted on, Nothing at all wrong with bolts, just using the right ones . Another one was the 60 foot 2 hander in the Melbourne Osaka, designed my Lawrie Davidson, left the engineering to one Skipper D Taylor, lost keel co skipper drowned, always some excuse, cheap!! Thing is, most builders and designers, when they design, only think in one medium, glass, or whatever, so everything is glass. When I build a boat I start with the keel and go up, I do not add the keel later Even in metal, the whole structure around that area, is the most important area of all
In timber, not so long back, floors were of bronze, or galv steel, the structure did not rely on frozen ham and pea soup to hold it together
boats were engineered, with strict rules adhered to by at least the pro builders, look at Heroshoffs scantlings
nope I would not go sailing offshore in most of todays boats.
And excuse if it has been already mentched, but the most notorious was Drum, Whitbread, but the cause was plain there

 

Some more news:
http://www.chron.com:80/disp/story.mpl/hotstories/5900127.html

Cheers.

 

The latest:

http://www.theeagle.com/local/Official--Design-flaw-may-have-contributed-to-sinking

Earl

 

Interim Report from TAMU

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

The page lets you download a PowerPoint presentation. No conclusions yet, but a couple of more pictures. Nothing more from Texas A&M until the USCG findings are completed "in several weeks."

Earl

 

Interesting pictures.... Still terrible tragic....

On the photo of the capsized boat, you can see there's two frames, at least I think I see them...
On the photo of the keel, you can see all bolts, but I'm seeing only pretty short bolts? (None long enough to rise above a frame in the keel area?)

On www.theeagle.com they state:
quote:
A&M System Assistant General Counsel Jerry Brown said that thin layer of fiberglass was found where the hull attached to the keel, a flat blade at the bottom of the boat that normally keeps it upright.

National standards require the fiberglass to be at least as thick as the bolts attaching the keel to the hull, Brown said Friday as he briefed the Texas A&M System Board of Regents on the status of the internal investigation. The bolts on the Cynthia Woods are 11/2 inches thick.

"The hull needed an extra inch of fiberglass to support the keel," Brown said, noting that the keel weighed nearly 5,000 pounds.
Quote ended.

So, the "keel is a flat blade at the bottom of the boat"...? WOW Big surprise...

"National standards require the fiberglass to be at least as thick as the bolts"?
So, if the keel is fixed to any hull by 30pcs 10 mm bolts, the hull thickness in that area will need only 10,5 mm to be approved...? No mention of the strength of the total laminat/ layup/moment/ testing- come on... If that is the case..I mean, if the national standard does not take into account heeling, moment, roll speed, extra stress?

"bolts on the Cynthia Woods are 11/2 inches thick.
"The hull needed an extra inch of fiberglass to support the keel""
1,5 inch... thats 38 mm? right, so actually they say that the keel was fixed to the hull in an area where the laminate had a thickness of only 12,7 mm?

Just me wondering.....

Anybody with access to actual bolt dimensions, keel footprint, length/ width etc?

 

Another one:

http://www.nzherald.co.nz/category/story.cfm?c_id=106&objectid=10529896

http://www.sail-world.com/CruisingA...48455&SRCID=0&ntid=39&tickeruid=0&tickerCID=0

Earl

 

Thanks, Earl.
I'm most sorry for the casualty.
Let me post here some excerpts and the capsized boat's image from the links you posted:


'Sergeant Wayne Lambert, of Tauranga police, said sea conditions were not rough at the time and the weather was mild.'
'They were sailing at more than 30kmh (16.2 knots!)....when they felt the yacht hit something.'
'We sailed for another couple of hundred metres before the boat went on its side...'
'The yacht remained on its side for 20 to 30 minutes...'
'...the boat started turning upside down.'

And here: http://www.bayofplentytimes.co.nz/localnews/storydisplay.cfm?storyid=3783357, we find:

"The yacht lurched to its side before tipping portside, causing the mast to flounder in the water.
"The yacht stayed like this for about half an hour..."
"Eventually the one metre swell swamped the main sail causing the yacht to completely capsize."
"....sea conditions were not rough and the weather was mild."
"Coastguard incident manager Brian Palmer said it did not appear the yacht had hit anything and it was not yet known how the keel had been lost."

So, perhaps another keel lost in mild weather without having hit something.

Fast machines, fast men, weak keels.

Cheers.

 

It appears that something is up on the standards front:

http://www.sailing.org/25460.php

Anyone know the gentlemen mentioned in the article?

Cheers,

Earl

 

Grégoire DOLTO is a french naval architect, one of the four fathers of the STIX number.

Robin LOBSCOMBE is a PhD C.Eng FRINA, RCD Structural Consultant, lecturers in small craft structures at the Southampton Institute and one of the principal authors of the ISO 12215 standard.

Cheers.

 

With such thin , high aspect keels on such big boats ,it is beginning to appear that the only way of guaranteeing structural reliability is to run the keel right thru to the deck, thus supporting it at two widely spaced points..

 

1/4 tonner

hello d'artois, what happened to the 1/4 tonner that you were planning to restore.Frank NED 7709

 

ISO 12215-9 update

As Gregoire Dolto and Robin Lombscombe inform at the present december/january issue of Practical Boatbuilder magazine, ISO 12215-9 on appendages and rig attachment will be go for final DIS in early 2009 and hopefully become an ISO standard by the end of the year.

From there:
Part 9 concentrates on providing design loads and design criteria while leaving the way open for designers to employ sophisticated engineering methods, such as grillage theory or finite elements analysis. As that would be excessive for designers of standard production boats, part 9 provides a whole series of simple scantling equations. Ulike part 5, these methods sit in Annexes, meaning "use them if you want to".


Cheers.

 

Guillermo,

There's no chance of knocking of the keel on your Banjer 37. A wise choice given the rias of Pontevedra. Hang on a mo'. No keels on Gunboats either.

Regards,

Perry

 

The U.S. Coast Guard report on the Cynthia Woods has been released:

http://www.d8externalaffairs.com/posted/425/CYNTHIA_WOODS_2_.246074.pdf


Earl