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  #1981  
Old 10-30-2013
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Re: Pros and cons of steel sailboats

Quote:
Originally Posted by bobperry View Post
Jon:
I have one of those drive in stories. I have another one where we were pulled over by a cop who insisted on seeing in the trunk. Mouse was in the trunk. His real name was Clarence but we all called him Mouse. He looked like a mouse and he was in the trunk.

I opened the trunk lid. Mouse looked up at the cop, Tex was the cop's name. We all knew him and he knew all of us. It was a small town. Mouse looked up at Tex and said, "Hello ossifer."

True story. This was in the days when the cop would give you a stern lecture and then send you home. And you know what? We respected Tex.

I'd just like to smell my old Olds again.

Now I am remembering Mouse stories. There was this time,,,,,,,,,,,,,,,
A couple of years ago I saw a '48 Chrysler Business Coupe in a collection. It was a huge gangster looking thing and being a Business Coupe it had the single most enormous trunk I have ever seen.

You could have stacked up bodies like cordwood in that thing - it would REALLY have lived up to its image.
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  #1982  
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Re: Pros and cons of steel sailboats

I'll make a half hearted attempt at getting this thread back on track .

I went to the BS web site and looked at the pipe 34" life"lines". I have two major problems with them.

One is the awkward agricultural appearance.

Two is far more serious. The ISAF Offshore Special Regulations for lifelines require a gap between lifelines of no more than 15". So 28" high works as does 30" but 34" does not. You would need a third lifeline if you wanted to be in compliance. And you would need to be in compliance if you ever entered an offshore "rally" or race. These regs are extensive and they are not arbitrary. I design to them as they represent a lot of effort aimed at producing rules for a safe boat. You can find them on line under ISAF.
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Last edited by bobperry; 10-30-2013 at 01:40 PM.
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  #1983  
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Re: Pros and cons of steel sailboats

Bob

In my time on foredeck a GOOD TOERAIL has been of far more value for staying onboard as my hands are both generally busy and there is nothing like a good foot brace to keep a secure position
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1981 J24 Tangent 2930
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If a dirty bottom slows you down what do you think it does to your boat
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  #1984  
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Re: Pros and cons of steel sailboats

I had a go at the origami boat building site and find some Brent boat's that are not that ugly. I would say that even if the design is very conservative, the general aspect is nice, for a home built boat, including the interior:











But I confess this stability curve (36ft) leaves me confused:





Most of the stability curves of steel boats that I have saw take into consideration the big weight of the boat (that contributes to the RM) and normally have not a big AVS neither a very low CG. Normally those boat have a lesser B/D ratio than on a much lighter fiberglass boat. Their weight gives them much of the stability they need. They do it that way for not increasing substantially the weight of a boat that is already very heavy.

On your stability curve, considering that is a low draft boat without a bulbed keel, you have a AVS and a GZ curve that needs a huge B/D ratio. Certainly over 40% and probably near 50%.

Since your 36ft weights 17,280 lbs and the ballast is 5700 lbs, that gives a B/D ratio of 32%. That looks fine to me but one that would make that curve impossible to get, considering the Draft 5'10" and a non bulbed keel. I would say that not even with a bulbed keel and that draft you would come close.

Also a bit confused with the value of max GZ for a your relatively narrow 36ft. If I understand well you are using meters as unit and that gives a GZ well over a 1m? That is a measure for a 40ft racing beamy boat

Brent can you explain me how do you manage that GZ curve?

Regards

Paulo
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Last edited by PCP; 10-30-2013 at 02:43 PM.
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  #1985  
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Re: Pros and cons of steel sailboats

Quote:
Originally Posted by PCP View Post
I had a go at the origami boat building site and find some Brent boat's that are not that ugly. I would say that even if the design is very conservative, the general aspect is nice, for a home built boat, including the interior:

Those "life rails" don't look to be 34". They look much closer to the standard height you see on most boats. Even so - without the 15" intermediate line as Bob mentioned above, very easy to fall right through that space. Sure seems like a dangerous design to me (and ISAF apparently).
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  #1986  
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Re: Pros and cons of steel sailboats

Not a bad looking hull though. Lovely interior.

I agree with Paulo. There is something very odd with that stability curve. I don't believe it for a second. Steel hull and deck, very moderate beam and draft, low ballast to displ ratio. You can't get the VCG down low enough to get a LPS more than 130 degrees with those numbers. I have never seen a stability curve that looked like that and I have looked at a lot of them. It is a BS curve. I'd like to know where Brent put the VCG. I don't think he calculates weights well enough to have an accurate VCG. Without an accurate VCG the curve is worthless. Maybe he'll publish his weight study here for us. If he does I'll post the weight study for FRANCIS LEE for comparison.

For comparison, when I designed the 50' YONI the client wanted a LPS of 135 degrees. I had to work hard to get that much. I gave the boat a displ of 50,000 lbs and 20,000 lbs. of lead ballast deep in a big alu fin. I used a high deadrise hull form and moderate beam. I got 135 degrees but it was not easy.
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Last edited by bobperry; 10-30-2013 at 03:40 PM.
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  #1987  
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Re: Pros and cons of steel sailboats

Quote:
Originally Posted by bobperry View Post
... I have never seen a stability curve that looked like that and I have looked at a lot of them. ..
That type of stability curve is typical of some narrow fast old designed performance cruisers with a big B/D ratio.

Have a look at the Contessa 32 GZ curve. The boat as a B/D ratio of 44%. The one from Brent has a considerably bigger AVS and a bigger stability at big heel angles.



The Max GZ of the Contessa 32 is only 0.7m, very far away from the 1.2m that is shown on the Brent's curve even considering that one is a 32ft and the other a 36ft.
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Last edited by PCP; 10-30-2013 at 04:05 PM.
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  #1988  
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Re: Pros and cons of steel sailboats

I never realized how contagious two foot itus is. Anything form 27 to 32, then
32 to 34 DE schooner, now I am looking at the Brent boat 36 foot DE could i put a schooner rig on that. I am suprised that I am not running a fever (2ft-itus).
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  #1989  
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Re: Pros and cons of steel sailboats

Paulo:
I'll buy the Contessa's curve, it's a narrow boat with a lot of ballast low. But that is a far cry from a LPS of 175 degrees that BS claims. I would estimate Brent's VCG at right at the DWL or maybe a hair above.
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Re: Pros and cons of steel sailboats

I'm confused. I thought having a heavier hull did not necessarily contribute to more favorable GZ nor to smaller area under the curve when inverted. I thought major factors were hull shape, B/P ratio and righting arm. Thought those issues plus shape of topsides and weight under water when inverted were the added issues when inverted. Spinning a steel barrow or a wood barrow floating in the water is just as easy. Thought weight of the skin of the boat has little to do with stability. Would think with heavier hull ( steel) it would actually be more difficult to achieve good curves c/w a light hull and greater portion of total weight in keel especially if contained in bulb lower down then seen in Brent's boats. Would agree good curve for when boat is inverted may be easier to achieve for narrow heavy boat less dependent on form stability.
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