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  #3241  
Old 01-16-2014
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Re: Pros and cons of steel sailboats

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Originally Posted by outbound View Post
Also seems apparent that in settings where steel may be appropriate aluminum may be a better choice. Larger group of modern designs, better sailing performance, easier maintenance with current methods, higher resale value/% of retained value and equal or greater strength with current designs. Only downside is less abrasion resistance.
With much higher initial cost, much higher odds of corrosion below the waterline, no antifouling available which is as effective as copper, which wont threaten to eat it, far more prone to metal fatigue , much trickier to weld , and a far more expensive, and harder to find building site .
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  #3242  
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Re: Pros and cons of steel sailboats

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Originally Posted by MikeJohns View Post
Brent if you were there, hadnít the hurricane stripped a lot of the sand from the beach and exposed reefs and boulders that ground up most of the boats washed ashore?
I have a cruising friend (Robert) that knew Moitessier well, Moitessier was very cavalier with Joshua with collisions and groundings thinking it was immune from damage. When Joshua went ashore he was actually in the bar and his boat was just anchored, he wrote some BS about being aboard !

As for Winston and construction, I didnít make that up the pro marine welder who inspected Winston said on BD net that she was built so. Easy to prove if you know the boat and owner so well they will have all the details.




....isnít my drum skin theory itís the accumulated knowledge and science that makes engineering and itís the theory of plates and shells that any engineer anywhere will tell you exactly the same



My problem adopting your engineering principles, thatís a good one from someone who claimed his boats had an AVS of 182 degrees !

I comprehend it all intuitively, thatís the problem, you donít, and I can show you that you donít, and have shown you that you donít.
And you constantly mix up diminutive steel tanks with proposed scaled up 60 foot frameless behemoths that simply wonít work. Thatís where you should be , addressing the silly claims that the design is intrinsically strong enough to scale to twice the size of the initial design you started with.

You also still havenít commented on the fact that other designs of yours rotated their keels because you misunderstood the structural adequacy. You lied when you said only the boat that tore holes after a high speed grounding suffered that fate didnít you !



Iíve designed more that you, mainly one off custom designs for shipyards, nothing like the variety or number of sailboats of Bob Perry here but I also design other vessels like patrol boats, ships, floating docks if anyone wantís something designed. I'm not just a yacht designer I will design yachts when pushed or starving :-).

Iíve never seen a Brent boat ever, because the 200 you claim built around the world amounted to something like under 40 if I remember rightly from Tad Roberts estimates, and the majority are in Canada, none in Tasmania or I would have done an inclining test on it by now !.
Interesting that you have to keep repeatedly quoting a typo, to support your arguments! Shows how feeble your arguments are
Only one of my boats tore her hull at the hull- keel joint, when they ignored the structural I had designed into her, which was in the plans I sold them. The rest, you are making up!
Your argument that Tad Roberts, who hides out on an island, knows more about how many of my boats there are than I, or my clients do , shows how you are grasping at straws to support your arguments. Cruise BC, and you will see plenty of them, sometimes many in a single anchorage. There are 4 in my current anchorage . None have any interest in going to the US , fast becoming a police state. I offered them some San Juan charts . No takers!
That is why you wont see them down there, except for those built there. None of my crew has any interest in going there to build any.
Evan, who built Winston's 3 Brentboats, and his daughter's Brentboat has built approximately the same number as I have , 38. They know Suzie , Ken and others who have built many. Many have long ago headed out to sea, and are no longer in this area. I often get pictures of those I have sent plans to, boats sailing or being built . Now how in hell would Tad Roberts know anything about them?
I checked Tad Robert's website. Not a single useful, practical cruising sailboat there.

What dented Bernard's boat was a plastic boat coming down on top of her. The plastic boat disintegrated , Joshua is still sailing.

Last edited by Brent Swain; 01-16-2014 at 09:26 PM.
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  #3243  
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Re: Pros and cons of steel sailboats

Brent
I was trying to give you a caution that intuiton doesn't translate into engineering fact. It's not the torn hull that's the issue and I have never said there were more than one that tore it's hull. I'm talking of the other example(s) that buckled their plate. But certainly your earlier design was prone to rotating keels into the hull, and even your very own boat which you yourself posted about on one forum ( learning as you go). Perhaps you'd forgotten, none of us is getting any younger

It's just that you were denying that there had been any more so it gets hard to make any point without going down Alice's rabbit hole.

It's significant that you intuitively presumed that the curve of the hull would be strong enough and provide enough support for the keel. I think it's a good example of why your intuitive scaling logic is perilous.

Tad Roberts simply looked up some official figures, can't see how that relates to his designs, he's educated and knows how to look stuff up and allow for statistical adjustments. He also gave you a weights and moments study for your 36 as a gift and worked up a stability curve for you for free and offered to validate it with an inclining test. He's been very helpful to you for free. You don't appreciate his work though and never thanked him.


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.What dented Bernard's boat was a plastic boat coming down on top of her. The plastic boat disintegrated , Joshua is still sailing.
That reminds me of the fate of a ferro cement sailboat in Queensland in a cyclone I have pics of somewhere. The steel workboat got washed on top of the yacht and ground her into small bits and a mat of mesh and twisted rod. The steel boat was pulled of afloat with a relatively undamaged hull apart from some prop and rudder damage!
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  #3244  
Old 01-17-2014
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Re: Pros and cons of steel sailboats

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Originally Posted by Brent Swain View Post
Before you waste lot of cruising time trying to make steel do what it really doesn't want to do, ask yourself "How important is it really ? How much cruising time it this worth giving up, for this?"
+10000000000000000000000000000

To every newb out there thinking about the pros and cons of building a steel boat, please pay very close attention to the above quote. He is absolutely right.

Heed his advice!

Buy a used fiberglass boat and go have some fun actually cruising.
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  #3245  
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Re: Pros and cons of steel sailboats

"Your argument that Tad Roberts, who hides out on an island,"

No need to keep getting nasty Brent. Why say that? You need to relax a bit.
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  #3246  
Old 01-18-2014
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Re: Pros and cons of steel sailboats

Quote:
Originally Posted by MikeJohns View Post
Brent
I was trying to give you a caution that intuiton doesn't translate into engineering fact. It's not the torn hull that's the issue and I have never said there were more than one that tore it's hull. I'm talking of the other example(s) that buckled their plate. But certainly your earlier design was prone to rotating keels into the hull, and even your very own boat which you yourself posted about on one forum ( learning as you go). Perhaps you'd forgotten, none of us is getting any younger

It's just that you were denying that there had been any more so it gets hard to make any point without going down Alice's rabbit hole.

It's significant that you intuitively presumed that the curve of the hull would be strong enough and provide enough support for the keel. I think it's a good example of why your intuitive scaling logic is perilous.

Tad Roberts simply looked up some official figures, can't see how that relates to his designs, he's educated and knows how to look stuff up and allow for statistical adjustments. He also gave you a weights and moments study for your 36 as a gift and worked up a stability curve for you for free and offered to validate it with an inclining test. He's been very helpful to you for free. You don't appreciate his work though and never thanked him.




That reminds me of the fate of a ferro cement sailboat in Queensland in a cyclone I have pics of somewhere. The steel workboat got washed on top of the yacht and ground her into small bits and a mat of mesh and twisted rod. The steel boat was pulled of afloat with a relatively undamaged hull apart from some prop and rudder damage!
The mistaken presumption on my boat was that 4 -1/2 inch by 4 inch flatbars on edge, across each keel, from chine to centreline, far more strength than I have ever seen on any twin keeler her size, and certainly far stronger than anything on the Laurent Giles designed Westerly, was adequate by virtue of being far stronger than anything other designers were specifying. If I was wrong, then so were they ,to a far greater degree. The only damage I got was a slightly dented hull, when the 1/2 inch by 4 inch flat bar on edge bent across its width. Unlike them, I have strengthened greatly the keel support on my designs specifications, which were not always followed. I am in no way responsible for failure of anyone to follow what I have specified.
Check out Steve's comments on Cruisers forums, when he said Silas Crosby has hit many rocks and logs at speed, with zero damage. Try that on any other designers' twin keelers, especially the plastic ones by Laurent Giles. You would tear the bottom out of any of them.
Friends, who arrived in Cabo just after the disaster there, told me that the Joshua had dents the size of a dingy , far bigger than the space between frames .
Tad Roberts joined the jeering, adolescent heckler gang on all aspects of my boats, then made up a number, based on imagination, as to how many of my boats have been built, calling me a liar in the process. I may owe him something ,but it is anything but a thank you.
Winston told me that if is boat had transverse frames for the NW passage trip ,it would have been severely dented by ice. He said it was thanks to the lack of transverse frames that it had zero dents.
Yet you CLAIM to know someone, who CLAIMS to be a welding inspector, who CLAIMS to know more about what is in Winston's boat than Winston does , the guy who built her and sailed her thru the NW passage ? Then you CLAIM to believe him? Admitting the last point doesn't make you look like a useful source of advice on anything.
Ferro cement is fragile .I found that out when I lost my first boat, a ferro boat on a reef in Fiji, in conditions which wouldn't have damaged any of my steel boats in any way.

Last edited by Brent Swain; 01-18-2014 at 08:40 PM.
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Re: Pros and cons of steel sailboats

Quote:
Originally Posted by smackdaddy View Post
+10000000000000000000000000000

To every newb out there thinking about the pros and cons of building a steel boat, please pay very close attention to the above quote. He is absolutely right.

Heed his advice!

Buy a used fiberglass boat and go have some fun actually cruising.
Before Steve built Silas Crosby, he arrived in Fiji on his Spencer 35, expecting to meet a family there, whom he had met earlier. They never arrived , having disappeared without a trace. They were never found . That is what convinced him he needed a steel boat. Since then, he has commented on the huge increase in peace of mind, when sailing at hull speed on a dark night, knowing he has steel, instead of plastic, between him, his family, and any floating debris out there. With some of the stuff I and my friends have hit on dark nights , many of them, and myself ,would not be here, had we been in anything other than a steel hull . We will never know how many other former cruisers, and their crews and families, are no longer here, for exactly that reason.
Smack says that would be a good thing! We disagree! Maybe it would be a good thing for Smack!

Last edited by Brent Swain; 01-18-2014 at 08:57 PM.
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Re: Pros and cons of steel sailboats

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Originally Posted by Brent Swain View Post
Yet you CLAIM to know someone, who CLAIMS to be a welding inspector, who CLAIMS to know more....
Isn't that your exact M.O.? You CLAIM to have a lot of "friends" telling you things that no one but you believes to be true.

You should be perfectly satisfied with this technique. It's classic BS.
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Re: Pros and cons of steel sailboats

One part of the indoctrination process in apprenticing for a designer, is to learn to treat your clients bank account as your own personal advertising budget, at your client's expense. That is why some designers advocate aluminium over steel, with total disregard for his clients costs. What is important for the designer is the boat looking pretty and sailing slightly faster, AFTER the client has spent years paying for her. There is no doubt that an aluminium boat will be slightly faster in light airs, and will never show red rust, and aluminium corrosion is less visible. Is this important enough to justify the huge increase in costs to the client, and to justify him taking that much longer to get away ? It isn't to the designer, who has the client thus pay his advertising costs for him. It may well be to the client, who may be looking at years longer on the treadmill, mainly for the benefit of the designer.

Last edited by Brent Swain; 01-18-2014 at 09:10 PM.
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Re: Pros and cons of steel sailboats

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Brian,

Where steel comes into its own is that it is very strong and stiff for any given cross sectional area. There are few if any boat building materials that come anywhere close. But steel is also very dense. Because of that an equal weight of any other boat building material has a much thicker cross section. Since the properties of materials (sheer not withstanding) are calculated as the square, cube or fourth power of the thickness (depending on the purpose of the calculation), it turns out that if you believe in the science, when viewed solely on a pound for pound basis, steel is one of the weakest boat building materials.

Where steel comes into its own is that it is pretty cheap relative to its strength, and it has a very high abrasion resistance.

The weight issue often gets dismissed by traditional cruising sailors, but does come into play in very real ways that directly impacts cruisers. When a boat is designed, its hull lines lock in a specific displacement and rate of displacement gain with additional immersion. In other words any given hull shape can only tolerate carrying a given amount of combined weight of hull, ballast, rig, hardware, engine and consumables, and the question then becomes how do you divvy up this weight between the various parts of the boat and what it carries.

If you compare two boats of equal strength, but constructed of different materials, and the hull of one weighs 40-50% more than the other due to the material (an increase which may be as much as a 10-20% of the overall displacement of the boat) that additional hull weight has to be accomodated somehow. That 'somehow' could be a mix of decreased ballast weight, lower carrying capacity, smaller tankage, less interior appointments and the like. And these trade off's translate to a smaller range, less stability, more roll, and so on. And none of that is good for a cruiser.

But, to answer your question, the case of aluminum it does take greater thickness to achieve the same bending, stiffness and puncture strength. But, if you believe the science, even with that greater thickness, an equal strength aluminum hull will be lighter than the comparable steel boat.

Jeff
1inch fir planking is around 3 lbs per sq ft, 3/16th plate is around 7.5 lbs per sq ft. Fir has a tensile strength of 1500 psi steel around 60,000. or 11250 psi for 3/16th plate. Thus 3/16th plate has 2.5 times the weight of 1 inch planking and 7.5 times the strength.
However wood only has tensile strength along the grain, very little across the grain, and in a cold molded fir hull only a third of the veneers has the grain going in any one direction. Steel has equal strength in all directions. Thus in a cold molded one inch thick hull, the tensile strength of wood is slightly over 1/3rd the tensile strength of wood, about 600 PSI. 3/16th steel is roughly 18.5 times the strength of 1 inch cold molded planking. However, in high stress areas, like chain plates and keel bolts, all loads are across the grain, on all three veneers.
There is nothing weaker than a wooden boat, unavoidably!

Last edited by Brent Swain; 01-18-2014 at 09:25 PM.
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