Advanced Commercial Aluminum Catamaran

Discussion in 'Multihulls' started by anthonydimare, Aug 7, 2015.

  1. Ad Hoc
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    Ad Hoc Naval Architect

    Alumium, was first used by the British chemist and inventor Humphry Davy in 1808. He was was trying to isolate electrolytically from the mineral alumina. He did write it -um and not -ium. But the pronunciation was deemed abominable by his peers and thus the "i" became -ium was added. Also this was in line with conforming to the precedent set at the time of other newly discovered elements of the time: potassium, sodium, magnesium, calcium, and strontium .

    Independent discovers of aluminium were made in 1886 on both side of the Atlantic, namely Hall in the US. They tended to use alumina and thus aluminum rather than the adopted -ium in the EU.
  2. Jetboy
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    Jetboy Senior Member

    There are two parts to this. First is volume. I'm only buying a small amount. I can't negotiate lower margins. With Carbon retail there is enormous - like 5000% - markup in carbon tubing. The cost for a large scale carbon manufacturer of tubing is low per foot on continuous filament over mandrel weaving machines. Aluminum tubing is manufactured in sufficient volume with competition to bring prices down to the cost of production plus a small margin.

    In 10 years I think you'll buy carbon tube and sheet goods by the lb just like steel and aluminum. Probably around $10lb - that's about what raw materials cost today.

    The second part is that aluminum and carbon are very different materials to manufacture with. So some applications favor a material that can be melted and poured or formed. Some favor a material that can be draped over forms and molds. Most boat parts favor a material that can be draped, can be oriented in specific directions for structural properties, can be thickened at critical areas, etc.

    My boat is almost all composite. I can't imagine the cost and effort to try to build a one off hull in aluminum. It would be astronomically expensive, heavy, and a maintenance nightmare. The only aluminum parts I used are the beams and mast. And the aluminum beams will be replaced at some point with composite complex shapes. I used aluminum because it was fast and easy.

    Both materials probably have their place in sailboats, but specifically in fast multihulls, I think aluminum use is and will continue to be on the decline. As such I wouldn't spend much time trying to build advanced aluminum manufacturing when FRP will generally replace it for most applications.
  3. Ad Hoc
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    Ad Hoc Naval Architect

    I’m sorry that is all nonsense and the kind of comments I would expect from a wet behind the ears student who has just learnt about carbon fibre in their material science lecture. The same “predictions” you have made were made when I was a student 30years ago…and are still being made ad nauseam. . Although these days it is nano-steel!!

    So your assertion of it being the same or cheaper has now become..well may be in 10 years time etc. And then to suggest material selection is about whether it can be melted or draped, I’m sorry you clearly have no idea about what is ‘design’ and how a design is manufactured and its objective, the SOR.

    Whilst you can’t imagine the cost I don’t have to speculate or guess, I know for a fact.

    The last composite boat I designed (commercial vessel) was using infused WR hulls with a Carbon Fibre deckhouse. All the same nonsense you are spouting was made by the owner to ”self-promote” the material and the “efficient lightweight” hull/design. The composite hull was exactly the same weight as the ally one, how do I know..because I designed it and have all the facts and figures when the vessel was going to be ally.

    And all the data/evidence from all previous composite designed hulls, the same. You do not gain any weight advantage when designing commercial vessels…why?..because there are strict codes of compliance called Classification society rules. Once you design the laminate to satisfy minimum weight of reinforcement and/or the stress levels required, there is no gain. One only has to look out the window in port/quay side, how many commercial vessel are made of composite that can be identified, for your assertion to be true?

    Pleasure boats do not need such compliance, nor are such vessel subjected to daily service of 8-12hours per day or more running 365days a year. Although I recent years, the lack of compliance checks is now changing owing to the introduction of the ISO rules being adopted by EU member states and elsewhere. So designing a shiny Gin palace, may, just may save you some weight but at an increase in cost. But those days are fading with the introduction of the ISO compliance many are adopting.

    Carbon fibre is not cheap, the base material is “comparable” to aluminium, but the tooling and manufacturing cost are huge. The skilled laminators and the highly controlled environment that must be maintained to ensure consistent quality (quality is important for commercial vessels - not just slapped together to build a wake board or canoe in a shed) all those “weight savings” that you et al espouse comes at a significant price. The tooling cost for a large composite vessel renders it way way too expensive unless one is going to build at least a run of 5 of them simply to break even. And I talking about any kind of vessel, but especially vessels that are 25m+.

    So whilst you may speculate and dream of a time in 10years and image draping cloth in some odd way dictates the design of a hull….i stick to facts, facts of designing with many different materials over the past 30 years. Your dreaming as noted previously is at variance with reality.
    bajansailor likes this.
  4. upchurchmr
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    upchurchmr Senior Member

    +1 for Ad Hoc.

    I heard the same stories 30+ years ago and the fantasy is still nowhere closer.

    Next fantasy will be 3D printing of composites - its all automated you know!

    Aerospace does not have to meet ISO type standards, it just has to be analysed and tested to perform as claimed, and the same cost story applies.
  5. redreuben
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    redreuben redreuben

    Ad Hoc

    Having read your contributions on here many times I have no quarrel with your knowledge, but your manner leaves much to be desired.
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  6. upchurchmr
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    upchurchmr Senior Member

    Reality is a tough pill to swallow.
    Its difficult to deliver the message and make most everyone happy.

    Ad Hoc does not need my defense, but I've seen this hundreds of times.

    You ought to be happy with a well stated set of facts rather than imagine some implied attitude.

    The typical current thought that "everyones opinion is worthwhile" leads to fantasies instead of engineering and economics and does the disservice of letting people go down a dead end path.
    Statements of fact/ experience should be countered with alternate facts to make progress.
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  7. hump101
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    hump101 Senior Member

    Here's some additional data points. We have a 15m commercial HSC which is built in alloy as per the clients requirement. The design is to DNV rules. There are around 30 hulls in service now, but we had an enquiry for a composite version so we performed the design calculations for this, also to DNV rules. For single skin wet layup the structural weight was higher than for alloy by a few %, but for an infused single skin it was lighter, again by a few %. However, this was for stitched triaxial reinforcement. We did not try an infused WR laminate as this would be heavier and WR is notorious for not infusing completely. I'm not aware of anyone infusing large WR structure since the 90's when we did a lot of work with the UKMoD mine hunter programme, so would be interested to hear more about what is going on.

    We also ran the calcs for sandwich composite construction using glass or carbon. We could save almost 20% of the structural weight over alloy using a sandwich laminate, and nearly 50% using a carbon/nomex sandwich. For this vessel the structural weight is only 20% of the total displacement, so not such a huge saving overall, and being a hard chine high speed hull, forming in alloy is easier than it would be for a 3D curved form.

    Most of our fabrication work is using composites, almost exclusively infused carbon tow in single skin or sandwich form. We pay typically £20/kg for carbon tow, and £10-£15/kg for resin, so not far off Jetboys numbers for materials, but labour is typically triple or quadruple that cost, particularly for small items. We also fabricate alloy components as required. Alloy is great for one-offs, you can't beat the rapid prototyping with a CNC lathe or mill, but for highly loaded items carbon is much more fatigue resistant for a given mass.

    Here in Europe most new commercial boats are built in composites these days, if they are not built in steel, though there are a few niche builders and many older alloy hulls still working, which gives a different impression if you look around a harbour. Through life service costs of alloy just can't compete with composites, and I think this is probably what is primarily driving the change, more than any performance gain.
  8. Jetboy
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    Jetboy Senior Member

    The weird thing is I flew to Africa on a carbon composite airplane recently... I guess I was just dreaming. Aluminum is the future!

    In all seriousness, there may be a point of demarcation where current rules favor aluminum or steel hulls - like 150 passenger fire ratings, etc. What we can establish I think pretty well is that, per foot, comparable boats that we do have retail prices for are less expensive in composites than aluminum, and less costly to maintain.
  9. DCockey
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    DCockey Senior Member

    By composites do you include glass or only carbon? The price difference between glass and carbon is significant.
  10. Squidly-Diddly
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    Squidly-Diddly Senior Member

    I think your question is about 60yrs behind the times.

    IIRC, it was directly after WW2 when massive contracts for massive amounts of basically disposable alum-aircraft ended that Grumman and others started making sturdy, lightweight boats out of aluminum.

    Today in the USA when you say "fishing boat" people tend to think of a plain small aluminum utility runabout, probably w/small outboard.

    While these are now cheap used (since they never rot and take lots of abuse) back in the day they were considered pretty futuristic, especially since their light weight allowed them to plane with small engines at high mpg.
  11. Leo Lazauskas
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    Leo Lazauskas Senior Member

    I'm confused by what you mean by "alloy".
    Ad Hoc uses "ally" to mean aluminium. Do you mean aluminium, or an alloy of two or more metals?
  12. Jetboy
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    Jetboy Senior Member

    I would include both. Really any fiber reinforced plastic. Heck if we get to a point where we have just pure plastics that work - those too. And ultimately I suspect that's where we may end up is printing boat parts in some form. But for now any type of FRP composite.
  13. Ad Hoc
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    Ad Hoc Naval Architect

    I think you're going to have to come up with more evidence than that to convince anyone here. You may be fooling yourself, owing to a penchant for the material, but those that work with both materials in the real world (not dreaming again), have very different opinions based upon actually designing and building them to commercial standards. Are you aware of what these standards are and what is required?

    That sounds about right, as we found too. But one never uses sandwich construction for the bottom of commercial boats, especially work boats. It's ok for those little runabouts, but not serious working boats. I don't know any operator that would use a sandwich cored bottom for their boat.

    All the commercial boats i do 95% are aluminium and every port/harbour I go into smaller boats (less than 50m) are circa 95% aluminium. BTW..i don't select the material choice..the SOR and hence design dictates the solution.

    C.Truk is the only windfarm commercial vessel that uses composite, but that's for economics of scale, as they have some 20+boats all the same. They have now started uses aluminium for their next boats now too...Danish yachts, hmmm..not sure why they decided composites. Their claim is their boats are lighter, but their larger boats are built to SOLAS which means the whole of the hull must be A60 fire protected - as composite does not pass the standard fire tests as per the rules. This is fire-insulation and yup...adds weight..thus what is claimed to be gained in one hand is lost in the weight of the fire protection.

    Notwithstanding these, i rarely see commercial composite boats in harbours/ports, expect for the odd pilot boat here and there.
  14. JSL
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    JSL Senior Member

    I would guess 'composite' would cover a 'mix' of materials. The first time I heard it used was for mine-sweepers: wood planks on aluminum (aluminium) frames.
    Moving on: carbon fibre. Electrical charges can be interesting. I have seen a sailboat which had an electrical strike (14,000v overhead power lines). Some of the 'juice' went down the shrouds and into carbon fibre reinforcement in way of the chain plates. Not a really good conductor but the results were "interesting" according to the surveyor.
    A friend of mine is currently fixing up a 74' composite boat that 'hit' some power lines.... he summed it up as ...." it is a whole new experience!"

  15. TANSL
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    TANSL Senior Member

    No, that's not right at all. The whole hull need not be A-60 fire class.
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