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Old 31-12-2014, 21:24   #31
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Re: 53 foot Cat breaks in half

Who is the naval architect you guys are referring to?

Steve.
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Old 31-12-2014, 21:49   #32
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Re: 53 foot Cat breaks in half

A mythical one.
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Old 01-01-2015, 02:17   #33
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Re: 53 foot Cat breaks in half

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Originally Posted by Brob2 View Post
I could be wrong, but I believe here and in the USA Naval architects and marine engineers are pretty much one and the same, unlike on land where architects and structural engineers are Spartans and Athenians?
No it is a bit like specialist Medicine....
Even though he probably studied it.....You wouldn't want your GP performing brain surgery.
But you would expect him to know who to call.
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Old 01-01-2015, 05:47   #34
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Re: 53 foot Cat breaks in half

I still don't know much more about how it broke, or how it sank. I did see this thing once when it was in Hamilton, under some expressway bridge I think, it was very impressive, but only slightly in line with any original Wharram design. The guy obviously regarded plans as only a point of creative departure. And that is fine if you know what you were doing, but he seems to have missed the memo on a lot of basic issues like displacement.

Wharram boats, structurally, are more what I would call a management exercise than an engineering one. If you don't know how to calculate the correct sail area for a boat (probably in most cases a guess anyway), you can do stuff like put on the sail area of 19th century workboat. If you are not confident on your ability to design rigid structures, you can build in redundancy in the form of excess beams, flexi structures, and add belts, suspenders, then another belt.

In layout they don't design it, they make everything optional or call it flexi space.

Then they give you less boat for the size than is reasonable, and emphasize all the ways in which it is better for having low windage, no bridgedecks, and so forth.

The thing about Wharrams though is that a lot of this fits in with his market. People like the demountability; the simplicity of building (if you don't count all the extra epoxy and timber you will use; People who have never gone to sea before like the low rigs; and most everyone likes the way they look if they can just take them for what they are, and not a comment on their own style.

Wharrams are hugely successful as a result, and deserve to be.

But all this leaves me wondering how they could have permited all this to happen. I don't personally believe that all the changes were approved. They were beyond what Wharram has ever shown itself comfortable with, not to mention capable of producing. This is a firm that evolves adaptations to Gaffs, not one that runs all the structural numbers for the Uni Rig. When they get adventurous they revert to the classics, not leap forward. As with their more traditional canoe designs.

However, it would be possible to manage some of the changes if they were interested in doing so

If more information makes it out, we will find out what happened to one degree or another.
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Old 01-01-2015, 05:55   #35
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Re: 53 foot Cat breaks in half

Greetings and welcome aboard the CF, ThomD.
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Old 01-01-2015, 08:27   #36
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Re: 53 foot Cat breaks in half

All that work and they were trying to sell it for only $105,000. Did it sell? Can someone look up the Canadian Registry and find out if the builder was still the owner at the time of the breakup?
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Old 01-01-2015, 08:46   #37
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Re: 53 foot Cat breaks in half

ThomD, I think you are selling Wharram way short really, im pretty sure he, like the vast majority of multihull designers is not a na, and neither do they need to be. When he started designing cats there was nobody doing what he was doing and he has been slowly evolving his designs ever since and long ago came up with a sensible formula that produces boats that have a safety record that any na would be envious of. Most designers draw shapes and proportions to meet the customers sor and then job the structural engineering out, but they are usually designing a different kind of boat for a customer, such as trying to build a boat on the bleeding edge to be faster than someone else or trying to design some obese roomaran to carry all the crap modern man wants to take with him. Wharram operates differently and designs boats he would want and if some other like minded soul wants to buy a set of plans, great.

Steve.
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Old 01-01-2015, 10:37   #38
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Re: 53 foot Cat breaks in half

Have a friend who built a cat that he is afraid to take out of the harbor after $300,000 plus in it. Love my monohull.
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Old 01-01-2015, 10:42   #39
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Re: 53 foot Cat breaks in half

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Originally Posted by admiralslater View Post
. In the end when asked the designer may have said to himself... hmmm... why not try that?
[snipped]
David
Here's another example of that:

95 foot TEN MILLION dollar yacht capsizes on launch.



10 mill$ poweryacht capsize during launch in Anacortes - Cruising Anarchy - Sailing Anarchy Forums
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Old 01-01-2015, 10:51   #40
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Re: 53 foot Cat breaks in half

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Have a friend who built a cat that he is afraid to take out of the harbor after $300,000 plus in it. Love my monohull.
You know I love my mono too, but this adds nothing at all to the conversation, and unless it's good natured teasing is uncalled for, Your point is?
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Old 01-01-2015, 10:54   #41
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Re: 53 foot Cat breaks in half

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Have a friend who built a cat that he is afraid to take out of the harbor after $300,000 plus in it. Love my monohull.
Is his name Hot Rod?
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Old 01-01-2015, 11:03   #42
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Re: 53 foot Cat breaks in half

I posted this observation on another forum but am putting it here for any CF Wharram owners. As designed Wharram rigs are Stayed to the hulls on the outside, the rig loads then pull the windward hull up into the beams which take the rig loads. The lashings are designed to keep the hulls located while adding flexibility for stress reduction.

On a cantilevered rig the beams will always be trying to pull up and off the windward hull, held down by only the lashings which were not designed for those loads. If you look at pictures of Nooka and compare to the Pahi 50 on Wharram's site you'll see they haven't been increased in size or frequency to compensate for this kind of load.

It was mentioned on boatdesign.net that the beams were steel, something that has been done before on Wharrams. If flotation isn't added to compensate they can sink the boat. One went down in the Great Lakes area back in the 70s or early 80s.

I hope we hear soon what actually happened, I'd guess though that it was something along these lines.
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Old 01-01-2015, 11:22   #43
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Re: 53 foot Cat breaks in half

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Originally Posted by senormechanico View Post
Here's another example of that:

95 foot TEN MILLION dollar yacht capsizes on launch.


Different level of stupidity all together. The boat you reference in Washington was incompetently launched by the yard in an unsafe manner and without the ballast installed.
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Old 01-01-2015, 11:47   #44
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Re: 53 foot Cat breaks in half

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Have a friend who built a cat that he is afraid to take out of the harbor after $300,000 plus in it. Love my monohull.
..I can help to override that fear in a weekend... as far have a 22kt wind and a good spinnaker...
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Old 01-01-2015, 11:55   #45
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Re: 53 foot Cat breaks in half

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No it is a bit like specialist Medicine....
Even though he probably studied it.....You wouldn't want your GP performing brain surgery.
But you would expect him to know who to call.
We must have a hybrid thing here. A good friend of mine took the 'Ocean and Naval Architectural Engineering' program at Memorial U. in NFLD and is a Naval Architect- now designs stuff like pilot boats and offshore vessels when he's not racing Jboats- but engineering was a big part of his program. He's both a professional engineer and an N.A.

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Originally Posted by Cavalier MK2 View Post

On a cantilevered rig the beams will always be trying to pull up and off the windward hull, held down by only the lashings which were not designed for those loads. If you look at pictures of Nooka and compare to the Pahi 50 on Wharram's site you'll see they haven't been increased in size or frequency to compensate for this kind of load.
The superstructure alone too looks as though it concentrates the structural load narrowly. Add that rig and you have a lot of relatively un-dispersed stress.
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