Metal Round Bottom Sail Boat

I came across this thread on "Bezier Curve Design". I think it is creative and know that it does work, and it works well. I would be interested in hearing more opinions on the method. It is detailed at:
http://metalsailboats.com/

I am the originator - Looking forward to replies.

 

Looking at the website I'd have a few comments.

Firstly it's nothing new, round hulls have been plated with small discrete sections since the advent of metal boat building. Even the round hull of a wooden ship is built with flat planks but they at least curve longitudinally. The method proposed here has discrete longitudinal sections which are problematic to longitudinal curvature unless the sections are numerous. Therein lies the problem.

To work so many small sections for a major area of the hull is going to be crippling time wise. Far better from a production perspective to use a radius chine if you want a round looking hull. They don't need to be slab sided either, you can put a lot of curvature into otherwise flat plates that don't need to be rolled to pull into the frame.

For the amount of welding if you wanted a round hull you'd be better off in every respect with long seams rather than numerous butts. ie you replace the trad timber planks with wider planks of metal NC cut. It's even common in Holland to lapstrake the metal strips so formed and simply fillet weld inside and out.

Butts ( vertical joins) are the worst joint to make in plating, they are more obvious to the eye and they are the hardest to achieve a fair result on a curved section. With numerous butts along a side you have the very worst arrangement. Just consider joint shrinkage for how many butt welds each side in the topsides ? 25,30,35 ....
Also very important if its to be alloy is the grade you recommend (especially with so many butt welds midships).

It seems to me on the website there's a lot of sales hype and talk of Bezier curves and B splines but in reality there's a lot of small flats that approach a curved surface with crippling labour. And it's no more a bezier method than classic timber boatbuilding.

There's also a complete lack of any naval architecture rational except some subjective comments about form. Where's the rational for a hullshape that can't be built with more sensible methods?

I'd really urge anyone building their own boat to go hard ( or softened) chine and keep the welding to the minimum . If you really want round then just use a radius chine and have someone roll it to the constant radius.

Read "Steel Away" by Moir and Smith then go and buy a used steel sailboat with some rusty spots and repair it and go sailing

 

Also a good summary here

http://www.kastenmarine.com/aluminum.htm


At present in the yard are two " planked" steel boats.

 

Mike Johns

Thank you so much for your reply. As I was reading your reply I was sure that you were saving the positive for last. But you had zero positives!

Since I do not want to seem like I am going on a RANT I will reply to your comments in several posts.

Since I developed the method, I chose to call it "bezier Curve Chine". Is there any harm in that. What is in a name anyway. It is a method that works and works well no matter what you call it.

Metalsailboats.com is about a building method. It is a building method that allows average skilled persons to build a true round hull. You do not need to be a boilermaker or professional builder. If that is not Naval Architecture I do not know what is!

You really want a true round hull, but you talk about crippling labor. Tell you what - Build your hard chine or radius chine and look at it for 20 years. Tell me about your crippling labor than. How much does your time mean now?

There are three big unresolved problem with "Radius Chine" design. By it's own nature, of using a single radius, severely limits hull shape. "Radius Chine" design does not produce true round designs. It's method forces much of the curved section at the turn of the chine below the design waterline. This makes the hull look slab sided. What is the point of the radius at the turn of the chine if you can not normally see the curved section?

You and I both know that the above is true. Using the same radius at the midsection for the stern produces a fat butt boat every time!!!! What a great idea. Lets design a boat around a radius.

Mike, I am looking to move on in design and construction. Lets use not be stuck in the past. We strive to improve - do we not.

Dennis Schaffer
http://metalsailboats.com

 

I'm sorry I don't see any positives at all in your method. And your MO is to knock every other method and pull your idea out the hat by the ears and suggest it's a great leap forward !

But it's a step back from simply rolling the plate and doing the job properly. Rolling would actually be similar work to all the bending you propose, and you can shape the plate longitudinally as well as transversely.
Have you even used a roller or English wheel ? With two profile boards it's quite accurate and I suspect a lot faster than the multiple bend faceted flat panel proposal. I suspect it would actually be faster overall. People can also pay a metalworker to form the plates for them.

But unless you really want a metal classic hull why bother ? Far better to look for a designer that works with the material rather than forcing the material onto an unsuitable shape. Otherwise just use a more suitable material.

And I'm interested in the technical points, for example what have you calculated as the weld shrinkage ? You are mute on this....

I don't agree with your comments at all on looks at all. It's easy to design good looking classic hulls with a radius chine, a lot of classic hulls had quite flat sections and a hard turn anyway, all you are doing is suggesting a large tumblehome is most desirable and then proffering a solution that I see as poor from a critical technical perspective.
Flat facets, crippling labor and far too much welding in the topsides. Then you are going to use lots of filler which is not good on alloy and prone to problems on alloy hulls in my experience.

Wouldn't it be better to design a hullshape which both looks good and suits sheet material rather than getting stuck on classic wooden forms which can be improved upon significantly from a NA perspective.

This might be better called the multiple vertical chine method and I really think youd be far better off for the welding to switch to NC cut longitudinal "planks" .

 

Not you and I ...

I've designed true round and constant radius that had little between them and balanced hulls, no fat stern.

Look at the projected lines in the cad image since it shows a lot more than a picture. That's no more than a single chine hull with a 800mm constant radius chine. But I recommend the hard chine version to new builders since the rolled chine costs around $8k more overall and a few weeks more work.

On a hard chine I just fillet the chine aft which gives a slightly better flow separation.

 

Mike Jones,

Correct - I have seen English Wheels, and have never used One. You are missing the point. What first time builder can use an English Wheel. First time builders can not build true round boats. Here is a way. They just want to build a boat not become a professional metalworkers.

The Bezier method enables them to do so. This is done by way of a completely engineered process. Right down to the shell plating. This process fit seamlessly together without limited hull shape.

The plates are no more forced to shape then in a magic (English) wheel. With all shell pattern marked for forming it took me only 5 hours to form all the free formed curved plating for the whole boat, and they would fit seamlessly to the framework. How long would it take your magic (English) wheel to do that.

Did you really look at my web site. Take off your blinder and open your mind. Maybe we can make it better!

Nice boat by the way.

Peace, I think we are both nicer than this exchange.
http://metalsailboats.com
Dennis Schaffer

 

The marketing tail tries to wag the dog. I'm concerned people will fall for this as a new and novel approach to boat building. But it's not. It's a very amateur alternative IMO.

If you build a metal boat you learn about metalwork. It takes what, maybe an hour to learn to use the stretching wheel. A similar length of time to learn to use a bending machine . Then consider how long does it take to learn to weld those alloy joins proficiently ? Alloy welding is a very hard skill to learn to do well. Get the relative skills in perspective and maybe hire a skilled metalworker for a day to come help shape your panels and maybe a pro welder to do your welds , or at least check your welds are actually decent.

Why put 35 Butt welds in your topsides and facet the lines longitudinally and then fix it up with filler when you could do it properly ?

Especially when radius chine is a versatile and much more sensible alternative. If the builder was sensible they'd select a better design that didn't require such effort but still looked good. This is called "design".

 

The method seems like a nightmare of vertical welds. It would be easier and cheaper to have long sections bent at a shop. Welding rod, grinding wheels and fairing will probably offset any savings you may get by not having the plate professionally bent.

 

DIY method--- empty oxygen bottles , a sand pit and a very heavy 4 wheel drive truck .

What thickness are we shaping here?

 

I read the website and it claims that "The two greatest costs in building a sailboat are the hull and the rigging". This is typical of salesmen trying to con buyers into thinking the interior cabinetry, sails, electrics, machinery, upholstery, etc. are a minor expense, when it is several times more than the hull and rigging.

 

Dennis, sorry to wet your parade but stop ranting that your "bezier" method being the alpha and omega of steel boat building....you remind us of Brent Swain and his boxy (read ugly) "origami" method.
Your method of using different radii is old hat as I said before, and Mike echoed my sentiments and by the way, I had built one of these type of boats in 1990 and as mentioned in an earlier post, problematic with aligning the sections without force - constant radius chine does not present this problem. Radius chine also built much faster with only about a third of the vertical welds of a similar variable radii such as yours present.

I think you must take off your blinders and look at some decent designed radius chine boats and I took liberty of adding a few Dix ones I had built in the past. The few shots of the completed Dix 43 from different angles makes a farce of your comments about constant radius chine. In fact, this boat was one of Dix earlier radius designed boats and the newer designs like the 38, 57 and 65 I had built were even tweaked further to look better still.
On this Dix 43 we used a 20kg container of fairing compound on the complete boat to remove dings and small unevenness here and there and most was sand down in effect using only about 10 - 12 kg fairing on complete hull. To fair your type of hull would need a complete plastering over with fairing bog and smoothed down.

In the late 80's early 90's or so a Dix radius chine boat was launched in Cape Town and the doyen of SA designers at the time (he designed a very well known BOC maxi racer that made headlines) was present at the launch and made a comment that it is one of the better and modern looking round bilge steel boats he have ever seen....he was flabbergasted to learn that it was indeed a constant radius chine hull. What better compliment can a designer have.
If a properly designed radius chine can fool a world renown yacht designer, it makes your remarks looks foolish.

Frosty, if you can not give sensible or constructive inputs on something you cannot fathom, rather keep quite

 

I would like to first thank everyone for taking the time to look into this, and provide me with a well rounded perspective.

I have always made a living in a metal shop, and have a problem with anyone who says it takes an hour to master a bend break. To know what you are doing on a break you have to be on it for a while. Yes anyone can make a simple bend; it does just go up and down doesn’t it. As for the English wheel, yes I have attempted to use one once. No way in hell is it comparable to a break.

The design I was reviewing had a single break configuration with the same die, and a stop set so that I am able to fly through the bends, and yes it would not be time consuming. I do not, have not build boats, but I am able to comment on the metal working.

There is something else that is bothering me, It seems some are saying this method of construction is a thing of the past, and others are saying it is new. If in fact it is a thing of the past, why didn't it work? Or did it?

The idea that a new marketing spin on an old method does not seem feasible as in the same breath you trash the method, and claim to have used the method.

Show me the results.

I agree with you, when saying the constant radius is an easier build with traditional build methods, I also agree the hard chine is even easier. I DON’T WANT THOSE. I do not like the way they look, when I build a boat it will be a metal construction and it will be a round bottom.

thesecondwind, I wrote you something on your contact section of your webpage just a min. ago, please check it out and let me know if you are interested.

By the way I didn't get the feeling anyone here was trying to sell me anything. So all the sales comments I just don't get.

The constant Dix plug is evident, but he doesn't have what I want, and is not in the business of designing what I want.

Grinding wheels are a dime a dozen, and weld shrinkage is not a factor when using standard gaps, and knowing what you are doing behind the stinger.

 

If you are referring to my comments on sales, it is about a quote from the website. Claims like that put in doubt the honesty of the information.
I think that methods that try to force a boat into a mathematical simple formula usually produce ugly, bad shapes. The method proposed is more complicated than a hull that uses conical sections, and has less flexibility. If you are going to do that amount of welding, pie shaped plates will allow you to make convex and concave hull sections with the same labor.

 

Marksail; metal working is not boatbuilding. I am a qualified boilermaker with 38 years of experience in different disciplines of steel sector and can tell you this - boat building in steel calls for different set of rules than "normal" metal working, period.

Obviously, your remark to welding is indicative that you had never build a boat and ignorant of real issues at hand. Firstly, shrinkage does matter foremost when welding a steel boat.
Sorry I lost half my life's pictures when a fire destroyed my office or I would have shown you some classic examples of pictures taken from amateur built boats whom had the same thoughts as you and ended up with "hungry horse" effect on hull plates. Last thing you want on steel boats are shrinkage when welding it hence a lot of thought and specific method goes into that and welds tried to be kept at a minimum.

I do not see the purpose of your posts since it seem you had already made up your mind on this old method now called the "berzier" method.
No need challenging me to produce the results since I have nothing to prove in boat building except to mention that a round bilge boat I built in 1992 to Al Mason's design I used the so called "berzier" method to do the compounded curvatures. Remember, Im a qualified b/maker and plate developing comes natural to me....

Secondwind made some claims about his method being less time consuming etc in post #19 and surely must rate amongst the top ten jokes of this decade. To illustrate I had taken the following verbatim from the "bezier" website and many other similar text to choose from and I quote;

It is definitely not builder friendly and this clown tries to sell this to amateurs who will swallow this crap in good faith for not knowing better. In short what he describe are sections of eccentric cones - iow, off center cone with 'slice" cut off simply put. Any of those tapering sections I can develop and roll on a normal pyramid plate rolls but can the amateur??
And the cracker is it is far more complicated and time consuming to produce that rather than the constant radius chine. Furthermore, to get the tapering sections fitted - different radii on each side of section to the radii of the adjoining sections are problematic for the amateur and even seasoned builder and would need some real persuasion with clamps, pullers and jacks....so much for easier and faster claims.

I had built round bilge, constant radius chine and the so now called "berzier' method and nothing beats radius chine for simplicity, ease of construction and aesthetically it looks best.

I stand to be corrected, but Bruce Roberts uses variable radii on his steel radius chine as well for what its worth.

Finally, Mike said it so did I somewhere and I will say it again for your benefit; nothing is new in boat building, methods "invented" now were usually tried before, sometimes decades and more ago. There is usually a reason why some of these "inventions' were tried before and not used commonly today.