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  #3011  
Old 01-02-2014
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Re: Pros and cons of steel sailboats

Quote:
Originally Posted by Faster View Post
Spent New Year's Eve at a nearby marina, and took a dock walk looking for metal boats. Not many, but an interesting variety:

Interesting waterproofing of the deck house:

Wait. What the hell? Steel boats don't leak Faster. That's not waterproofing. It's just to cut down on the heat from the blazing PNW sun.
Faster and bobperry like this.
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Re: Pros and cons of steel sailboats

Quote:
Originally Posted by NCC320 View Post
.........

No doubt when MOM and my boat collide, my fiberglass boat will be the one going to the bottom, but I still like mine better. I'll be careful not to get into such a collision. ...................

If you have a heavier displacment solid GRP hull it will hold up quite well in a collision, Foam core ULDB won't.
But Mom is an interesting example, on BD net a pic was posted of her after she sat her stern down on a rock after a grounding, the resultant damage is a good example of the lack of panel support, caused simply by the boats own weight and lack of framing to distribute the load. Must have been disheartening for the owners.

Your boat would probably have survived this without damage. Steel boats can be made a lot tougher than this with a very small amount of material and a boat this size in steel should have been bomb proof. There are a lot of similar examples in Brent boats, don't let his marketing fool you into thinking they are extraordinarily tough.
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  #3013  
Old 01-02-2014
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Re: Pros and cons of steel sailboats

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Originally Posted by smackdaddy View Post
Wait. What the hell? Steel boats don't leak Faster. That's not waterproofing. It's just to cut down on the heat from the blazing PNW sun.
That's a Newporter 40, a plywood boat. Some of my clients upgraded from one to a brentboat 36
That is what it takes to stop a wooden deck from leaking.

Last edited by Brent Swain; 01-02-2014 at 07:47 PM.
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Re: Pros and cons of steel sailboats

I see Brent. In your typical intellectual, approach to the subject you are going to assume that all wooden boats have deck structures like the Newporter. And, it is Newporter, not Newport.
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Re: Pros and cons of steel sailboats

Quote:
Originally Posted by bobperry View Post
I see Brent. In your typical intellectual, approach to the subject you are going to assume that all wooden boats have deck structures like the Newporter. And, it is Newporter, not Newport.
Well, customers must not mind the leaky plywood since this one is going for $80K:

Sea J II


And the far superior Dove II can't find a buyer at $20K. Oh the humanity.

Quote:
Originally Posted by Brent Swain View Post
That's a Newport 40, a plywood boat. Some of my clients upgraded from one to a brentboat 36
That is what it takes to stop a wooden deck from leaking.
Based on the numbers, I'd call that a significant downgrade.
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Re: Pros and cons of steel sailboats

Quote:
Originally Posted by MikeJohns View Post
Give a man enough rope !


What I indicated was that if your proposed revolutionary theory was valid then it’s applicable to a simple beam too. All I did was show you a comparison between two beams, one bent within it’s elastic limit as in your building method and one that was formed with no pre stress whatsoever.
Under load the beam with the ‘Brent pre stress arc’ was less able to withstand a point load. All you were supposed to take away from that is that your structural argument is a fallacy. It’s as valid for a beam section as it is for a hull structure when considering local panel loads.
The other situation which is far stronger is for the inner structure to be in tension rather than either neutral or compression. That is otherwise known as a ‘pre-tensioned’. That’s stronger again. Your method puts the pre-tensioned bit in pre compression, what that means is that it assists the arc in straightening out rather than resisting it. Your arguments are inside out, and simply wrong. You were claiming all over the place that it was a structural arch but that was also shown to be a complete fallacy.

So again your 36 footers are apparently strong enough but they dent easily and with large dents under relatively low level impacts than they should, so they are not tough in that regard. But for everyone’s sake, before you start promoting 60 foot versions of your boat, go ask anyone with a bit of real structural knowledge. Try and find anyone other than you that thinks this is a valid argument. Even load test a structure yourself.

Importantly and sounding like a broken record ….Your method doesn’t make your boats stronger, it makes them weaker than they could be and more prone to large denting from point load. For real strength the plate should become a diaphragm under load so that it is in tension and that takes adequate framing.
And again: You just don’t understand buckling at all it’s got nothing to do with tensile or compressive material properties nor the tripping of the stiffeners, it’s about ‘snap-through’ instability of the hull.

As for denting 5 or 6mm plate with either a sledge or a pick next to a frame you are deluded if you think you could put a hole in a hull with either. And as I said where are these properly framed boats that holed so easily? They are just in your imagination, it’s just not a valid observation.
I also said grillage can yield before the plate ruptures which is why Gringo didn’t have any holes in her plate. Gringo was also extensively transversely framed. And you use the Gringo example for your own ends at times so she is a good example of how transverse framing keeps the plate in place so it can take stress rather than simply buckling under a far lower load which takes far less energy and is far more catastrophic.

Now lets look at rotating keels into the hull once again. This is a significant issue, you know very well there were more boats built to your own design than the tall tale with an unnamed boat, unnamed owner, and variable location.
It shows that your presumed strength from curvature didn’t exist and that the supporting plate buckled easily in low speed collisions. It’s a good example of intuition being wrong, no different to your intuition that your design could scale frameless to 60 feet. When in reality anything much over 40 feet would be inadequate to meet any sensible offshore design head requirements, and would be significantly prone to grounding damage.

As for Lawyers telling you your designs are safe; lets presume for a minute that is true, and the Lawyer actually said that, (which I doubt with your record). What do you think that lawyer would say if you were the designer of a 60 foot design that just killed it’s crew and that expert professional witnesses were testifying that they had told you that your design was inadequate, and that your understanding of structures was abysmal ?

All the tall tales of incredible strength tend to ignore that fact that most of the boats involved were not built to your design but had more transverse framing. For example the NW passage boat you use for vindication had both thicker plate and extensive transverses not in your plans. In fact I’d suggest that most of the BS boats built have significantly more framing than shown in your plans.

Then you have the temerity to compare other designers plate first then frame construction method with your design and pretend it vindicates your design methodology. And now Joshua !

Bernard Moitessier’s “Joshua” that you mention had deep floors (transverses) and closely spaced transverse frames from the floor to the deck beam which were fully ‘fixed’ at both ends tied into floors and deck beams ( end fixity of 1 ). So you are way off likening Joshua to your designs or saying she had minimal framing she was a very strong design.


The fact is that you made dangerous assumptions in the presumed strength of your construction method. Those assumptions are wrong. I've asked you before and I'll never get an answer becsaue you simply don't know....What head of water do you think would collapse the fore-part of your 36 footer ? How about a 60 footer ? Why is this important? Do you know?

Your stability arguments are also hype, your small steel designs are on the tender side and the best estimate of AVS is closer to 135 degrees than the 180 you initially touted. That’s just a by product of using steel for small boats.
Initially we used to put the longitudinals in after the hull was pulled together. It took only hand pressure to push them in. Thus ""hand pressure' is something Mike considers structurally relevant in his designs. If hand pressure is relevant to the strength of his designs. then I would seek another designer, who designs with a greater safety margin. Sounds like flimsy designing to me.
When you bend anything, the inside of the curve is under compression, the outside under tension. That is one of the most basic principles of structural engineering. Anyone who is incapable of grasping such a simple concept, is definitely no engineer, and a poor source of advice on anything pertaining to engineering. Anyone who claims that if you weld angles to the inside of a plate, then bend it in a curve, the extreme outward pressure of the angles under compression is less than "hand pressure" is definitely no engineer, and poor source of any advice on engineering. He could always weld angles to along piece of plate, leaving just enough space under them to fit his fingers in ,then have a friend crank the plate into a curve, with the angles on the inside, and his fingers under the angles ,and "feel the pressure." His fingers would be quickly amputated !
It would be interesting to lay an angle alongside one which has been welded inside a hull before curving it, and see if there is any difference in length.
Again, Mike compares angles welded inside a hull, with a 2 inch weld every 4 inches , before curving it to a beam out in the open, attached to nothing !
No Mike, they don't behave the same. No Mike , you cant stretch the several feet of 3/16th plate, with a tensile strength of 11250 lbs. per lineal inch , by pushing on the end of an inch by 1inch by 3/8th inch angle, welded along it.
No Mike the plate wont stretch the plates welded onto it at an angle ,at 11250 lbs per linear inch tensile strength, diagonally, which they would have to do, in order to flatten out
No Mike, a longitudinal welded to a plate is not the same as an angle laying unattached to anything, laying out in the open. The ends are as solidly supported from any longitudinal movement, as your frames ending on a keel or deck.
No Mike a longitudinal will not slide freely along a plate it is welded to with a 2 inch weld every 4 inches ,nor will it stretch the 3/16th plate diagonally.
No Mike, the first 36 I built, which pounded for 16 days on a Baja beach, just south of San Ignacio, and was pulled off thru 8 to 12 ft surf , being lifted and dropped on hard packed sand, for a quarter mile without any serious dents, did not "dent easily."
What "Head of water" does it take to match the forces of a 36 being lifted up 12 feet and dropped repeatedly on sand too hard to leave a foot print in, for a quarter mile? How does "Head of water' Equate to a sharp pint hitting a hull? It doesn't!
No Mike , Don Shores 36" Viski" which pounded across 300 yards of Fijian coral reef in big surf, while leaving Suva, and was pulled off by a tug thru similar surf, with NO serious dents did not "Dent easily." You can see this boat behind Muddy Waters pub in Nanaimo. No hull dents , just a dented bulwark, where she ran into a freighter off Gibraltar ( with no serious damage ). You can read about it in his book "Around the World on Viski" available at Harbour Chandleries in Nanaimo.
No Mike , none of my boats have extra framing, beyond what I have designed in .You know of any ?
Name one! Show us the pictures of the extra framing.

Its interesting, this ESP you claim to have, claiming you know more about what goes into a boat than the builder of 38 of them, and the designer. If you put that kind of mental telepathy to work buying your next lottery ticket, you wont have to masquerade as an engineer any more. How about giving us some winning numbers here, so we can test your claim out? We don't mind sharing that kind of winnings.
Your drum skin theory is interesting. You could consider the support which strong points such as the chines, centreline and decks provide, far stronger than any transverse frames, as the rims of your drum. You say they don't count structurally? Then you are no engineer!
As long as there is outside curve , you have compression, not the tension in your drum skin. It t doesn't get there until it has been straightened out.
What saved Gringo was she was hit with a blunt object, not a sharp point, She was also saved by those huge, fully welded steel bulkheads, called decks and bottom plate. Transverse frames parallel to the impact had zero effect . Had she been hit with a sharp point right next to the frame, the frame would have increased the odds of her holing , by giving the plate hard point to stretch against.
A transverse frame will only stop holing if the sharp point lands directly on a frame. What are the odds of that happening. If it misses the frame, it increases the odds of holing.
No, a pickaxe wont go thru 6 mm plate but will thru the 1/8th inch plate commonly used for 36 ft fully framed hulls, especially if you hit right next to a frame. Not so easily with 3/16th plate I use, with no hard point frames to stretch against.
Tad Roberts , whom I have never, met calculated the ultimate stability of my 36 at 165 degrees . Jim the Russian computer whizz, put the lines in his computer, and it gave the ultimate stability at 175 degrees, posted on the origamiboats site, which is what my model tests gave me. Two factors which gave us the ultimate stability problems , flush decks and excessive beam, my boats have neither of.
The boat with the keel problem is called "Mishar" and at last report was moored at the Airport Marina in Richmond BC. I have never met the current owner, but met the previous owner at Fanning Island, on his way to New Zealand and back to BC, a trouble free voyage. It was his second Brentboat.

Last edited by Brent Swain; 01-02-2014 at 10:03 PM.
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Re: Pros and cons of steel sailboats

Brent:
Why do you try to discuss "engineering" when you display over and over that you have problems with numbers? I think you are free and loose with the term "engineering". Maybe "my guess is" would work better for you. You have never presented any engineering here just vague generalities.
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Re: Pros and cons of steel sailboats

Brent, I've adjusted your signature:

Brent Swain, Boat Guesser, Builder, and author of "Origami Metal Boatbuilding"
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Re: Pros and cons of steel sailboats

Quote:
Originally Posted by Brent Swain View Post
Initially we used to put the longitudinals in after the hull was pulled together. It took only hand pressure to push them in. Thus ""hand pressure' is something Mike considers structurally relevant in his designs. If hand pressure is relevant to the strength of his designs. then I would seek another designer, who designs with a greater safety margin. Sounds like flimsy designing to me.
When you bend anything, the inside of the curve is under compression, the outside under tension. That is one of the most basic principles of structural engineering. Anyone who is incapable of grasping such a simple concept, is definitely no engineer, and a poor source of advice on anything pertaining to engineering. Anyone who claims that if you weld angles to the inside of a plate, then bend it in a curve, the extreme outward pressure of the angles under compression is less than "hand pressure" is definitely no engineer, and poor source of any advice on engineering. He could always weld angles to along piece of plate, leaving just enough space under them to fit his fingers in ,then have a friend crank the plate into a curve, with the angles on the inside, and his fingers under the angles ,and "feel the pressure." His fingers would be quickly amputated !
It would be interesting to lay an angle alongside one which has been welded inside a hull before curving it, and see if there is any difference in length.
Again, Mike compares angles welded inside a hull, with a 2 inch weld every 4 inches , before curving it to a beam out in the open, attached to nothing !
No Mike, they don't behave the same. No Mike , you cant stretch the several feet of 3/16th plate, with a tensile strength of 11250 lbs. per lineal inch , by pushing on the end of an inch by 1inch by 3/8th inch angle, welded along it.
No Mike, a longitudinal welded to a plate is not the same as an angle laying unattached to anything, laying out in the open. The ends are as solidly supported from any longitudinal movement, as your frames ending on a keel or deck.
No Mike, the first 36 I built, which pounded for 16 days on a Baja beach, just south of San Ignacio, and was pulled off thru 8 to 12 ft surf , being lifted and dropped on hard packed sand, for a quarter mile without any serious dents, did not "dent easily."
No Mike , Don Shores 36" Viski" which pounded across 300 yards of Fijian coral reef in big surf, while leaving Suva, and was pulled off by a tug thru similar surf, with NO serious dents did not "Dent easily." You can see this boat behind Muddy Waters pub in Nanaimo. No hull dents , just a dented bulwark, where she ran into a freighter off Gibraltar ( with no serious damage ). You can read about it in his book "Around the World on Viski" available at Harbour Chandleries in Nanaimo.
No Mike , none of my boats have extra framing, beyond what I have designed in .You know of any ?
Name one! Show us the pictures of the extra framing.

Its interesting, this ESP you claim to have, claiming you know more about what goes into a boat than the builder of 38 of them, and the designer. If you put that kind of mental telepathy to work buying your next lottery ticket, you wont have to masquerade as an engineer any more. How about giving us some winning numbers here, so we can test your claim out? We don't mind sharing that kind of winnings.
Your drum skin theory is interesting. You could consider the support which strong points such as the chines, centreline and decks provide, far stronger than any transverse frames, as the rims of your drum. You say they don't count structurally? Then you are no engineer!


....because that makes no effin sense!
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Re: Pros and cons of steel sailboats

Quote:
Originally Posted by MikeJohns View Post
Give a man enough rope !


What I indicated was that if your proposed revolutionary theory was valid then it’s applicable to a simple beam too. All I did was show you a comparison between two beams, one bent within it’s elastic limit as in your building method and one that was formed with no pre stress whatsoever.
Under load the beam with the ‘Brent pre stress arc’ was less able to withstand a point load. All you were supposed to take away from that is that your structural argument is a fallacy. It’s as valid for a beam section as it is for a hull structure when considering local panel loads.
The other situation which is far stronger is for the inner structure to be in tension rather than either neutral or compression. That is otherwise known as a ‘pre-tensioned’. That’s stronger again. Your method puts the pre-tensioned bit in pre compression, what that means is that it assists the arc in straightening out rather than resisting it. Your arguments are inside out, and simply wrong. You were claiming all over the place that it was a structural arch but that was also shown to be a complete fallacy.

So again your 36 footers are apparently strong enough but they dent easily and with large dents under relatively low level impacts than they should, so they are not tough in that regard. But for everyone’s sake, before you start promoting 60 foot versions of your boat, go ask anyone with a bit of real structural knowledge. Try and find anyone other than you that thinks this is a valid argument. Even load test a structure yourself.

Importantly and sounding like a broken record ….Your method doesn’t make your boats stronger, it makes them weaker than they could be and more prone to large denting from point load. For real strength the plate should become a diaphragm under load so that it is in tension and that takes adequate framing.
And again: You just don’t understand buckling at all it’s got nothing to do with tensile or compressive material properties nor the tripping of the stiffeners, it’s about ‘snap-through’ instability of the hull.

As for denting 5 or 6mm plate with either a sledge or a pick next to a frame you are deluded if you think you could put a hole in a hull with either. And as I said where are these properly framed boats that holed so easily? They are just in your imagination, it’s just not a valid observation.
I also said grillage can yield before the plate ruptures which is why Gringo didn’t have any holes in her plate. Gringo was also extensively transversely framed. And you use the Gringo example for your own ends at times so she is a good example of how transverse framing keeps the plate in place so it can take stress rather than simply buckling under a far lower load which takes far less energy and is far more catastrophic.

Now lets look at rotating keels into the hull once again. This is a significant issue, you know very well there were more boats built to your own design than the tall tale with an unnamed boat, unnamed owner, and variable location.
It shows that your presumed strength from curvature didn’t exist and that the supporting plate buckled easily in low speed collisions. It’s a good example of intuition being wrong, no different to your intuition that your design could scale frameless to 60 feet. When in reality anything much over 40 feet would be inadequate to meet any sensible offshore design head requirements, and would be significantly prone to grounding damage.

As for Lawyers telling you your designs are safe; lets presume for a minute that is true, and the Lawyer actually said that, (which I doubt with your record). What do you think that lawyer would say if you were the designer of a 60 foot design that just killed it’s crew and that expert professional witnesses were testifying that they had told you that your design was inadequate, and that your understanding of structures was abysmal ?

All the tall tales of incredible strength tend to ignore that fact that most of the boats involved were not built to your design but had more transverse framing. For example the NW passage boat you use for vindication had both thicker plate and extensive transverses not in your plans. In fact I’d suggest that most of the BS boats built have significantly more framing than shown in your plans.

Then you have the temerity to compare other designers plate first then frame construction method with your design and pretend it vindicates your design methodology. And now Joshua !

Bernard Moitessier’s “Joshua” that you mention had deep floors (transverses) and closely spaced transverse frames from the floor to the deck beam which were fully ‘fixed’ at both ends tied into floors and deck beams ( end fixity of 1 ). So you are way off likening Joshua to your designs or saying she had minimal framing she was a very strong design.


The fact is that you made dangerous assumptions in the presumed strength of your construction method. Those assumptions are wrong. I've asked you before and I'll never get an answer becsaue you simply don't know....What head of water do you think would collapse the fore-part of your 36 footer ? How about a 60 footer ? Why is this important? Do you know?

Your stability arguments are also hype, your small steel designs are on the tender side and the best estimate of AVS is closer to 135 degrees than the 180 you initially touted. That’s just a by product of using steel for small boats.
Initially we used to put the longitudinals in after the hull was pulled together. It took only hand pressure to push them in. Thus ""hand pressure' is something Mike considers structurally relevant in his designs. If hand pressure is relevant to the strength of his designs. then I would seek another designer, who designs with a greater safety margin. Sounds like flimsy designing to me.
When you bend anything, the inside of the curve is under compression, the outside under tension. That is one of the most basic principles of structural engineering. Anyone who is incapable of grasping such a simple concept, is definitely no engineer, and a poor source of advice on anything pertaining to engineering. Anyone who claims that if you weld angles to the inside of a plate, then bend it in a curve, the extreme outward pressure of the angles under compression is less than "hand pressure" is definitely no engineer, and poor source of any advice on engineering. He could always weld angles to along piece of plate, leaving just enough space under them to fit his fingers in ,then have a friend crank the plate into a curve, with the angles on the inside, and his fingers under the angles ,and "feel the pressure." His fingers would be quickly amputated !
It would be interesting to lay an angle alongside one which has been welded inside a hull before curving it, and see if there is any difference in length.
Again, Mike compares angles welded inside a hull, with a 2 inch weld every 4 inches , before curving it to a beam out in the open, attached to nothing !
No Mike, they don't behave the same. No Mike , you cant stretch the several feet of 3/16th plate, with a tensile strength of 11250 lbs. per lineal inch , by pushing on the end of an inch by 1inch by 3/8th inch angle, welded along it.
No Mike, a longitudinal welded to a plate is not the same as an angle laying unattached to anything, laying out in the open. The ends are as solidly supported from any longitudinal movement, as your frames ending on a keel or deck.
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