can it be done in steel?

I mentioned 5mm plate because I won't recomend building a 30' steel hull using 10g sheet. My 5mm is probably over kill, 3mm would suffice below water but the same equipment required and skills levels apply.

It's easy to post pics of spring hammers and a 5tonne Nazel air hammer but they're whole lot different to work with and not suitablefor shaping 10g, 3-5mm plate for a boat, unless you like using lots of filler to fair out the bumps.

 

It's easy to do a lot of things. If power hammers aren't suitable for shaping, why did you throw out the suggestion?

How much fill and fairing would be needed to make this shape acceptable? How is this process even applicable for the compound curves needed in the posted rendering?

This shows 10 gauge as almost 4 mm.

If 3mm is OK, that would make it even easier.

http://www.tedpella.com/company_html/gauge.htm

g ------ in -------------- in -------------- mm

6 -----13/64 ------- 0.203125 ------- 5.159375
7 ------3/16 ------- 0.1875 --------- 4.7625
8 -----11/64 ------- 0.171875 ------- 4.365625
9 ------5/32 ------- 0.15625 --------- 3.96875
10 -----9/64 ------- 0.140625 ------- 3.571875
11------1/8 -------- 0.125 ----------- 3.175
12 -----7/64 ------- 0.109375 ------- 2.778125

I suppose it would come down to individual skills and acceptable finish as to how hard it would be to shape the part. Most power hammers are adjustable for force and anvil/hammer shapes and finishing with a 2/3lb hand hammer would get it within the realm of acceptable with a little grinding and a little fairing to finish it.

The easiest would be to just have it done by those who do it regularly and have the equipment. But as Kevin Morin stated, lines are needed, plus an actual plan wouldn't hurt. As I stated above, that small strip has minimal compound curvature but the sides above have an awful lot just above the small strip.

 

Look at this web site.http://metalsailboats.com

 

that's an interesting site! never heard of the Bezier curve- it does seem to involve a LOT of tooling such as a brake--they are not cheap. but it gets astounding results. Seems like a lot of work...? could be viable for this design though..

 

The Bezier curves or surfaces, NURBS, is exactly what you're using to make your drawings.
The construction method called "Bezier" is a fallacy

 

Dennis Schaffer, aka "thesecondwind", is originator of what he calls the "Bezier Method" and has previously started a thread about the method: http://www.boatdesign.net/forums/boat-design/bezier-curve-chine-32420.html It was also extensively discussed in another thread: http://www.boatdesign.net/forums/boat-design/metal-round-bottom-sail-boat-45360.html

 

Tugboat,

You do not need to buy a "Press Brake". The shell patterns can be
formed in a low end press brake at any fabrication company. The
shell plating for the "12.5" were formed in six hours. They all fit the
framing perfectly - no need to force anything. After the shell plates are
formed you will not need the press break again. Borrow a press break
for a couple of hours.

Tamsl,

"Bezier Curve" is a name - Do not be so anal. Have you ever heard
the expression of "What in a Name". Know what I mean?

Dcockey

Hi, How would you design and build an aluminum "one of" true round - tumblehome hull like the "Bezier 12.5" as easily as I did.

aka

 

I'm sorry but I do not know what you mean.
Bezier curves are a well-defined pattern element used to define shapes of objects (used for the first time in the automotive industry), but that can never be a constructive method.
To say that one uses Bezier construction method is to say nothing, giving the impression of a very high tech. If explained, in some way, this method of construction, I'm sure I'll have to accept their excellence. The name, though sounds nice, does not explain anything, nor implies high quality boat construction.

 

Tanzl,

It is a "Name". I know it is not 100% technically correct. You know
that and I know that. Some people would look up the definition and find
that it is a "Free form" curve of some type.

The bottom line is that "Bezier Curve" (Can I say That) is a true
round boat building method. Can we write about our thoughts on
that.

A Rose by any other name is still a Rose!

aka

 

The cross section of a boat, drawn using Bezier curves, can have knuckles and sharp corners.
Drawing with Bezier curves does not guarantee, has nothing to do, with a rounded bilge. It has nothing to do with developable surfaces nor with "ease of construction". Nor indicate a higher quality of construction.
I guess what they want to convey with that terminology but I think, it is my opinion, totally wrong.

 

What if the method was called the "Schaffer Method" instead of the "Bezier Method"?

 

It's really "Schaffer Method" a method of building boats?, then OK. Is it another way to dazzle the unwary without explaining what the method is?, then forget this other name.

 

Hull in plating phase with plate preformed using press brake. While possible to push/pull plating into position preforming takes out any additional stress and fabrication goes much quicker.

Lots of fancy words being bandied about but talking just isn't same as doing

 

Thanks for the PM

Yes Dennis Schaffer's method is a bit crude and it's unnecessary. Considering it's quite cheap and straight forward getting plates rolled to a constant radius. And constant radius chine will give an overall better and faster result.

As for roses by any other name: Bezier wouldn't be impressed. Why not call it an Einstein space curve method or any other misapplied catchy phrase ? It annoys the people who know what a Bezier curve actually is.

I posted two images here:
http://www.boatdesign.net/forums/boat-design/metal-round-bottom-sail-boat-45360-3.html#post596167
on the left Dennis's hullform is fitted instead with a constant curve radius chine, on the right is the rather unnecessary continually variable radius that comprises the "special" method. Which is actually just segmented cones formed on a press brake. Nothing special or new or patentable, it's actually been done for a century.
The constant radius chine is actually the newer method and with a hullform so suitable for a constant radius you'd have to ask why on earth do it the hard way ?. Why form cones when you could form a constant radius and get almost exactly the same hullform.

Using a constant radius is so close as to be indistinguishable from the press brake conic method as shown in the website, except it wouldn't need any filler if well constructed and there will be less welding as the same radius run through all the sections.

 

I don't think Dennis intended to do harm or guide people down the wrong path. I imagine that he got excited about being able to produce a hull shape with simple metal shaping equipment (a brake).

After looking through his website, my strong suggestion would be to update it by clearly stating what the trade-offs are using this approach. (I don't posses sufficient knowledge to comment on the hydrodynamic content.)

The individual segments can indeed be produced using a simple method with little skill required for the brake equipment but an amatuer/garage/backyard builder would have to become well skilled at welding, filling and correcting the inevitable welding details that need attention.

The linear amount of welding has increased by at least a factor of 20, which for a single builder can increase the number of small but non-trivial welding errors and missed spots. More time would be spent checking using dye penetrants, etc.

If the amount of rod/wire used during welding does not result in a consistent and smooth weld bead, additional sanding/grinding time is needed to achieve good fairing results in comparison to what would already be required for a standard method. More welding, more grinding/sanding.

All metals deform and move when heated so a puzzle-piece structure like this in the hands of an amatuer builder may require substantial more tweaking than a hull produced using standard methods. More pieces, potentially more deformation.

Since his website appears to be targeted at non-professional people like myself with a dream of a beautifully faired hull single project, I would like to know in advance what it really takes from start to finish. I can only speculate for myself but using Mr Schaffer's method for my project would ultimately end up with my seeking out the paid services of those with more expertise than I have to correct what I could not foresee and many, many more hours beyond just cutting and shaping the individual pieces. He appears to underestimate the required work, skills and time demanded by this method. It must be the reason why this method has not become the standard. This method takes more time to finish a faired hull.

I applaud his enthusiasm and good intentions but it needs to be objectively balanced by what is now a familiar statement to me which appears in this forum quite often: boats are always a compromise.