Aluminum Boat Buildng in shipyads?

Discussion in 'Metal Boat Building' started by eng.naval, May 22, 2012.

  1. eng.naval
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    eng.naval Junior Member

    Does anyone know the cost of building an aluminum boat compared to the cost of the same boat in steel?
    As far as i know the difference will be in:
    - Aluminum cost vs Steel cost.
    - Welding man hours cost.
     
  2. Ad Hoc
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    Ad Hoc Naval Architect

    that is about the sum of it.

    The problem is experience.

    Some very good yards will be around 500 man hours per tonne...others 1000 man hours per tonne. Thus there is a big difference in total costs, which is dependent upon the experience of the yard.

    So, not such an easy answer to give. As what is a good value for one yard may be totally different for another.
     
  3. daiquiri
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    daiquiri Engineering and Design

    I would also add the quality of design to the list, if we are talking about small vessels. An incomplete or imprecise set of plans, which leaves the burden of figuring out solutions for a myriad of big and small problems (which inevitably arise during the build) to the boatyard, can make both the number of work hours and the (equally payed) idling hours soar up...
     
  4. Tad
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    Tad Boat Designer

    Handling hours are also different. One man can move a fair sized piece of aluminum which would require a crane(or something) if it was steel........
     
  5. DCockey
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    DCockey Senior Member

    Can surface prep and paintings/coating costs, both material and labor, differ significantly for "similar" boats built in aluminum vs steel? Are these costs typically a higher fraction of the total costs for smaller vessels compared to large ships?
     
  6. Ad Hoc
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    Ad Hoc Naval Architect

    It is very rare, if at all, if yards breakdown the labour costs into such minutiae of tasks. This is generally all rolled up into the "labour rate" for the whole function.

    So to weld a frame, in steel or ally, the total time would be given. Including in that total, would be surface prep for welding etc. But surface prep & painting etc is a different function, and would be listed under the appropriate labour task. However, it still is all wrapped up into total man-hours since that is all that matters, the total for the whole build. Since one would not use a labour rate for welding on analuminium hull and then the painting of the aluminium using steel hours. Thus the total is all the matters for costings/estimation.
     
  7. DCockey
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    DCockey Senior Member

    Anyone know the answer to my question about relative surface prep and painting/coating costs between aluminum and steel construction? The original poster asked about the cost of building an aluminum boat compared to the cost of the same boat in steel? which would presumably include painting/coating the boat.

    Disclaimer - I'm just curious and interested. Not planning to build a boat of steel or aluminum, not developing any cost estimates.
     
  8. SleepyOldDog
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    SleepyOldDog Junior Member

    Ayman,
    Another important area for aluminum ships is cathodic protection. US Navy has had recent problems - http://www.paintsquare.com/news/?fuseaction=view&id=5830&nl_versionid=1033
    Aluminum also has a finite fatigue life. More structural engineering analysis is required...
    I believe there must be a very compelling reason for using aluminum - Speed, light weight, etc. to warrant the extra engineering/building cost.
    good luck
     
  9. Stumble
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    Stumble Senior Member

    Don't forget that an aluminium hull will be much lighter assuming similar size/design, and will therefore typically require smaller engines, and get better fuel economy. The fuel economy you don't pay for at the yard, but if you can get away will smaller engines that can significantly offset any additional cost to build in aluminium in the first place.
     
  10. eng.naval
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    eng.naval Junior Member

    Thanks all for the replies this was very helpful.
    I might use another phrase for the question to be clearer. In Egypt, we use the tariff $/ton to calculate the cost of building a hull for the ship owners. I don't know how they estimate the cost in the other countries. This tariff, of course, excludes the machinery, outfitting, navigation equipment,electric installations, painting and all other costs which NOT relevant to the hull and superstructure construction cost (material, subassembly and final assembly)
    The question here is for the same hull, what the difference in building the vessel in aluminium and building it in steel?
    In other words, If I asked a shipyard to build me say a tank using aluminium and another one using steel, what should I expect the cost difference? Is it two times the cost, three times....? I'm not looking for an accurate number I'm just looking for an approximate one.
    It would be helpful also if someone can tell me the difference in the cost of steel and aluminium per ton in general. (marine grades)
     
  11. APP
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    APP Junior Member

    Hi

    I am searching some general data for boat alluminum alloy welding cost, expressed in welded feet (or meters) within an 8 hours working day, e.g in America, Australia or Europe. Practically, I seek the average number of welded feet/hour. It refers to skilled workers (or semiskilled if you have data) including preparation time, smoking cigarette as said, etc. It can be given separately for plates and scantlings, if for scantlings I think it might take longer to weld one foot length.

    Thanks for any reply,
    Regards
    APP
     
  12. mastcolin
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    mastcolin Senior Member

    Aluminium yachts are not generally blasted. They are allowed (paint supplier recommendation) a mechanical grinding prep. Steel yachts are either gritblasted or built from shop primed steel. Grit blasting hull is extra cost over mechanical prep of substrate.

    It obviously depends on the builder but the amount of filler can vary. In NL steel hulls normally take more filler but this is more to do with quality of construction - they are generally more poorly build with regards fairness.

    Aluminium yachts don't need so much coatings in interior.Most alloy bilges are less paint/coats than steel. Superstructure interiors are often unpainted. This saves material and cost.

    Exterior wise there isn't normally any difference in schemes (yes this means that alloy is probably massively over specd but you can't not follow spec otherwise the owner's rep will look at you funny. Actually as painter it isn't too bad. The price includes this over engineering. The owner pays.)

    Unless you decide to use a certain Awlgrip alloy recommendation which wants you to apply MilSpec and 545 on the alloy substrate before you start filling. It probably works but I don't know anyone who is daft enough to use this spec when you can use the same spec as on steel ie 1 coat of Hullgard Extra...which also doesn't require you to sand before filling unlike their other recommendation. I struggle to use this word here. I have no idea who benefits from this "recommendation".

    Alloy is limited to range of usuable antifouling (due to risk of corrosion effect from free copper). These alloy compatible antifoulings are more expensive generally than equivalent usuable on steel.

    Longterm? Alloy yachts probably suffer more problematic corrosion in areas of dissimilar metals eg stainless etc. Hulls are no problems. Superstructures can be nightmares near windows, hinges, grabrails etc
     
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  13. mydauphin
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    mydauphin Senior Member

    Depends on quality of finish. Is it a boat or a true yacht? Yachts are all faired. The quality of welder and fitting, will determine fairing costs. All in all aluminum is almost double cost of hull, but not nearly a big difference in overall cost of comparable boats because steel ship with cost more in machinery and moving stuff around.

    As simple an answer to a very complicated question.
     

  14. eng.naval
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    eng.naval Junior Member

    Thank you mydauphin. You're right it's a simple answer and it's what I needed.
     
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