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Old 07-05-2013, 15:36   #76
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Re: Cost of Aluminum Hull and Deck ?

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Originally Posted by Sand crab View Post
What is the cost difference for Sealium vs the standard alu plate that one might use for ship building?
According to one supplier, Selium is an Alcan product, and apparently it has better welded physical properties than the more typical 5083 alloy:

Selium Sheets and Plates, Marine Grade Aluminium Alloys from Ullrich Aluminium

In naval architecture, we always engineer to the welded properties of the material which are considerably less than the virgin metal properties. This is unlike steel where the welded properties are as good as the virgin metal properties. The link above also discusses some of the advantages. So if you can engineer it properly, you may end up with a slightly lighter hull than if you used 5083. What the cost is, I don't know, it might be somewhere on the website. Traditionally, prices for aluminum are fairly volatile, so what might be good one month may not be so good the next.

Eric
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Old 07-05-2013, 16:35   #77
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Re: Cost of Aluminum Hull and Deck ?

With aluminium fit and welding are critical. We had a member here who built a trimaran by having the plates computer cut and then paying a welder to put them together.

So to get an aluminium boat there are going to be two key issues. First a good building site and second a trained and experienced welder. There's going to be more planning than for a steel boat as making it up as you go along is not going to work.

I got a "quote" for a 40 odd ft Dix design (hull and deck only) for about $90k when I was first doing my planning. This would be a good starting point.

I'd be guessing $5k for a Dix or Van de Stadt, 500 hours of welding at (say) $100 an hour so $50k, $40 of plate and framing and $5k worth of rent. And there's still going to be the rest of the boat so it's going to be at least a $200k and 3+ year project.

Got to be cheaper, easier and much more pleasant to buy a nice boat and then to "improve" it over 10 years or to do one of the quicker build cat designs.
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Old 08-05-2013, 03:56   #78
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Re: Cost of Aluminum Hull and Deck ?

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Originally Posted by ewsponberg View Post
According to one supplier, Selium is an Alcan product, and apparently it has better welded physical properties than the more typical 5083 alloy:

Selium Sheets and Plates, Marine Grade Aluminium Alloys from Ullrich Aluminium

In naval architecture, we always engineer to the welded properties of the material which are considerably less than the virgin metal properties. This is unlike steel where the welded properties are as good as the virgin metal properties. The link above also discusses some of the advantages. So if you can engineer it properly, you may end up with a slightly lighter hull than if you used 5083. What the cost is, I don't know, it might be somewhere on the website. Traditionally, prices for aluminum are fairly volatile, so what might be good one month may not be so good the next.

Eric
cant find prices. . .[IMG][/IMG]
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Old 08-05-2013, 05:56   #79
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Re: Cost of aluminum hull and deck?

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A Mig welder (Lincoln) with 12 metres of remote and hand peice, approx $3000-00 all inclusive,

Bottle of gas, $130-00, Yearly hire of said bottle of Argon gas, Approx $150-00

Roll of Aluminium Mig wire, Approx $40-00 per roll. You will need a few of them,

The steel for a 40 foot cat, $10,000-00 to $15,000-00 Approx, Total,

Aluminium and steel Sheets are approximately the same price,

Welding both is much of a muchness, Same process, different materials,

Getting a good ally welder, You need a Boilermaker with the skills Required,

Above costs were what I actually paid for mine,

And before you lot start, I am an Engineering Blacksmith, Boilermaker/ DLI Welder with 49 years experience in all facets of Engineering, Including ship building and repair,

Cheers,
Brian,
Mr B you are my Hero! Thanks for your valuable info!
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Old 08-05-2013, 06:25   #80
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Re: Cost of Aluminum Hull and Deck ?

Another Great Info I have found on the Web.
Aluminum Quote comparisons

"Aluminum is what it is all about. Before you get caught up in the details let me first outline the aluminum alloys that I regard as suitable for building a sea going vessel. Plate alloys 5083 & 5086 are the most suitable hull material. There is little to choose between them, although 5083 perhaps has the edge with respect to mechanical properties. Both alloys are an excellent choice. Extrusions like angle and pipe are available in both grades, although 5086 is much more readily available in the USA, and 5083 is more common in Europe.

There is also a slightly cheaper alternative 6063 or the ubiquitous 6061, which are a little cheaper, rather stiffer but they are not marine alloys (they contain some copper to give them added strength). Copper in aluminum is bad news in salt water. Just look at any unprotected aluminum mast after a couple of years. It corrodes rather nicely with some salt spray. One can however use these alloys in the interior of the vessel for stiffening the deck etc. where you are quite sure they will never be wet for any length of time. I personally think that if you are going too all the trouble of building a boat then use 5083 or 5086 extrusions. It didn't add more than 6% to the material costs for my boat.

Then there is the subject of tempers. This is usually defined as H32 or H321 or H116 or H111 etc. I have only the following reliable information to contribute.

Generally for plate below the waterline - H321 or H116 is best. It has the required mechanical and corrosion properties. The difference between H321 and H116, is that the H116 temper has an additional acidic accelerated corrosion test in its specification which checks that the material is predominantly free from continuous grain, boundary networks which are implicated in some types of corrosion (exfoliation and pitting). A reference I have is Aluminum-magnesium alloys 5086 and 5456 H116 by Brooks C.L. Naval Engineers Journal, August 1970. Otherwise H116 is equivalent to H321 in every way mechanically as I understand it. I don't want to get more technical than that, so if you have more questions read the journal reference. I am quite certain that H321 is as good, but as H116 costs no more, why settle for less (well plate sizes may be a more important consideration, so don't lose sleep over it). H32 is adequate mechanically but by may have a hidden potential for corrosion problems both above and below the water line unless painted, as a result of the 'as manufactured', crystal structure of the plate.

Suitable extrusions tempers in the 5086 & 5083 alloys are H32 & H111. For some reason H 112 is not to be used? I don't have more information about this.

One last point deals with pipe. The most suitable pipe for any application below the waterline is schedule 80. It has a much thicker wall than the equivalent schedule 40, and thus should last longer with respect to corrosion. This pipe is seriously expensive though, and normally comes only in 20ft. lengths, so check that your design uses one or two sizes only, if possible. Another anomaly is that schedule 80 pipe is differently specified compared to any other old pipe. A 3/4 inch sched. 80 pipe has an outside diameter (OD) of 1.050 inches and a wall thickness of 0.154 inches. A 3 1/2" has an OD of 4" and so on. My advice is to ask for a catalog."
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Old 08-05-2013, 07:43   #81
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Re: Cost of Aluminum Hull and Deck ?

All the above is well and good, and in an ideal world it makes perfect sense. However, at my end of boat design, we find very often that structural shapes--flat bars, angles, channels, tubes, pipes, etc.--are not nearly as widely available as one would like. The selection of suitable sizes and thicknesses just is not very broad for the 5000 series alloys as compared to the 6000 series. Also, some countries simply don't have 5,000 series alloy shapes, so your stuck with what you can get.

This happened on one of my designs, Project Amazon, back in the 1990s. We designed it for 5456 alloy, actually, used a lot by the US Navy and readily available in the US in plate and shapes. We thought the boat was going to be built in the US, and then the owner decided he could get a much better price in South Africa. At the time, the South Africans haven't even heard of 5456, and certainly couldn't get it. The only way they built boats down there was with 5083 plating and 6061 structural shapes. So we had to go over the whole design one more time and check all the scantlings for the new alloys, and make changes accordingly.

So, in the end, we have to check the available sources of aluminum for where the boat is going to be built. What are the alloys, thicknesses, and shapes available in each alloy, and then we engineer and design accordingly.

Eric
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Old 09-05-2013, 22:16   #82
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Re: Cost of Aluminum Hull and Deck ?

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see brent swain,oragami boats

...........but dont let the pretty pictures fool you!.............working with aluminium is not as clean as you think,and the welding fumes fairly noxious.

plus your initial lay out for tooling and welding machines will probably cost as much as it would to buy a cheap second hand fiberglass boat
brent swain,oragami boats. I took a look over the top on this manufacture design and building. Looks Clean and looks easy to some extent.



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