Aluminium Hull + Cost

Hello,

I am trying to figure how much aluminium sheets would a - 86x12 meter and 4 meter draft - ship need ? It would be a monohull as well.

Thank you,
SET Project

 

Welcome to the forum SET

Simple answer...a lot ..!!

 

As Ad Hoc says, it will certainly be a lot of material needed.
Can you supply some more info about this project please SET?
How far have you progressed with it so far?
What type of vessel is your 86 metre ship, and what will it be used for?
Do you have a rough initial lines plan yet?

 

Hello,

I want to create a theoretical model of a sail based monohull trading vessel using mainly aluminium for the hull as it provides great characteristics and recyclable value.
I've run down the pricing per tonne of aluminium 5000 (on a 5 year period : $2,311/t) and the average square meter on aluminium sheet covers (5,56m²)... To add I don't have lines drawn out, so where should I turn myself too for an initial design ?

Thank you
SET Project

 

Can you clarify what the price means? Also, a square meter of any material only covers a square meter.

 

The price signifies that on a 5 year period aluminium 5000 (noted : A5000) is noted to cost $2,311 per tonne. However, I have calculated that it would cost, in theory, $85,507 . So, for that price you can cover a rectangle (dimensions : 84x12x4) of aluminium 5082.

This is how I've come to that conclusion :

calculating the surface area of each side, so
84x12 = 1,032m² for one side -> 2 sides = 2,064m²
12x4 = 48m² -> 2 sides = 96m²
86x4 = 344m² -> 2 sides = 688m²

Total surface area = 2,848 m², and again this is based on a rectangle so it stands as a theoretical value.
Then, I've noted that one single sheet of A5000 is equal to : 5,56m².
Therefore -> 2,848 / 5,56

So, in theory I would need approximately : 512,23 sheets of A5000. To add , one sheet (size 60"x144") = 71,39kg.
Thus making the total weight : 512,23 x 71,39 = 36,568 kg or approximately 37 tonnes.

Finally, as I mentioned earlier the price per tonne is -> 1t = $2,311. So, we can calculate : 37 tonnes x $2,311 = $85,507
So the theoretical price will be : $85,507.

 

Sigh.....
You are going to need a complete preliminary design before you can even start to begin to answer the question of cost. FWIW, in the quantities needed for shipbuilding, even though it is delivered as sheet, it is sold by the pound. Additionally, there will be wastage of ~20-25% in fabrication. Finally, material costs are generally less than 10% of the total cost of fabrication. It is often cheaper to have higher wastage and less fabrication time because of the difference in the labor costs to material costs.

Seriously, unless this is for a student project, you are woefully un-prepared. Hull alone, you are looking at a 10-20 million USD build. Go look at any yacht sales website for what the base costs will be, try this link.
Selection of Yachts For Sale | Superyachts For Sale | Fraser https://www.fraseryachts.com/en/yachts-for-sale/

 

I have noticed that it was sold by the pound for certain manufacturers. As for wastage, I am seeking to use aluminium material because the wastage can be recycled, so the approx 20% is not a huge issue but still is something to take into account, obviously.

And, I am not considering a yacht type vessel, but I will look at the overall pricing. 10-20 Million, okay.

Thank you
SET Project

 

Even on a plain boat, the cost of the aluminum plating will be less than 5% of the total cost. Framing and welding supplies will be more. Aluminum can be recycled, but what you will sell the scrap for is not much. Trading vessels are heavy. They need to be for the abuse they get when working. Unless you have at least a preliminary design (not simply a drawing) , the calculations make no sense. The shape of the hull, the framing type, what class or other regulations to comply with, area of operation, etc. will determine and drive the design and cost.

 

Try L20naval, right now they are busy designing Grain de Sail 2, a 50m aluminum cargo schooner with a projected payload of 300-350t. Grain de Sail 2 commence à se dévoiler | Mer et Marine https://www.meretmarine.com/fr/content/le-voilier-grain-de-sail-2-commence-se-devoiler

This is no pipe dream, Grain de Sail already has one 24m vessel in commercial operation on a triangle route, as I write the vessel is on the second leg of its third voyage, en route from NY to the Dominican Republic.

 

Sadly, way way off the mark there.
Why?..because you need to account for:

Credit rating - does the yard struggle to pay suppliers month to month, or do they have a very black bank account - this influences prices offered to the yard,
Labour rates,
Overheads for the yard - so how much per sq/m does it cost to keep that sq/m running per year.
Consumables - wire/gas/grinders welding sets,
Lifting equipment in the yard - as less = more manual labour = higher production costs,
Level of certification - how many welders are coded, how many are basic fabby's etc etc,
QA- what, if any, QA and QC is in the yard - and how is is monitored/policed,
Storage facility in the yard - can it only handle a JIT, or is there plenty of space available for months of consumables to be stored,

And so on.

All the above need to be accounted for in the price per tonne.

And it is different for each yard in different locations and countries.....and then, as JEH et al note, you really need a Design, surface areas alone is just one element of the structural design.

If it is a brand new design this value can be as high as 45%.

If the yard are willing to "wait" for every single frame, girder, bracket, TB, etc etc to be fully modelling in 3D, and then arranged on sheets for nesting for each thickness, then this value can slowly come down to around 25%.
But this requires many many months and pre-planning and advanced deisgn work. But all yard's scream for cutparts once the ink is dry on the paper - thus, wastage goes up, to speed up delivery of cut parts.

And on it goes...

 

Hello Rumars,

I haven't heard of Grain de Sail, but it is interesting to see the ideas coming, and which I find very innovative. There is TOWT another company which emphasizes the use of sail trading. https://www.towt.eu/voilier-cargo-towt/

SET Project

 

Hello Ad Hoc,

Thank you for the run down of essentials I need to take into account to have an overall idea of budgeting!

SET

 

I think you are too optimistic about the price of aluminum sheets.. Don't know where you learned the price. Based on the London LME price of 2021-12-29, the price of one ton of pure aluminum is $2807.5. But note : this price is the warehouse price of pure aluminum ingots, not the price of 5083 aluminum plates that have been made and delivered to your factory.

Here, we can get 5083 aluminum plates at double the price. If you purchase in large quantities, you may be able to negotiate a better price. But it is definitely higher than $3000.

Your calculation did not mention the thickness of the aluminum plate. You cannot calculate the weight of a plate without knowing the thickness. Judging by the data in your calculations, the thickness of the aluminum plate you use is 4.76mm.
This thickness is probably used to build boats of 30-40 feet, but your ship is 86 meters . Obviously you cannot use such a thin aluminum plate. I estimate that your boat will need about 15mm or thicker aluminum plates. Then the weight of your aluminum plate and the corresponding price should be increased by 4 times or more.

In addition to the surface of the hull, there are many internal frames and deck and deck structures. The weight of this part is roughly equivalent to that of the hull. Of course, in your calculations, the hull is simply estimated as a cuboid, which is larger than the real hull surface area, and can be regarded as the actual amount including the loss. That is to double your estimate.

Then the weight of aluminum needed for your boat is approximately:
37*4*2 = 296 t

Suppose your boat has a block coefficient of 0.65, calculated based on the waterline length of 84 meters
The displacement of your boat is:
84*12*4*0.65=2620.8 t

While the weight of a general steel cargo ship is about 1/5 of the displacement, your ship is aluminum will have a slight advantage (about 30% weight reduction), I think 296t is a relatively reasonable data (but still optimistic)

 

Thank you for the detailed answer! It is a solid point made.

Yes, I am recognizing the fact that my calculations might have been a little optimistic, such as the thickness impacting the weight... as well as the overall cost of Aluminium. To note : It is said that pricing will increase (a forecasted increase of 6% for 2022) due to energy consumption, the carbon footprint taxes etc. thus lower offering meaning that demand will rise being that there will a more "limited" source produced per year... emphasizing the idea of price increasing in Aluminium.

SET Project