Fiberglass vs Steel Hull they both claim the best

If you compare the plain costs of building a fiberglass hull with the costs of a welded steel hull, the fiberglass hull will be cheaper. But, who has paid for the mold of that GRP hull?

If the comparison is ment for a one off, the full costs of the mold are part of the building costs of this GRP hull. And this counts for the positive and for the negative building method, whereas the negative method is the more expensive one, because of the complex design of of those molds. You first have to construct and build a plug, on which the mold is formed. And you need more molds for the deck and superstructure. If you for example plan an integrated rubbing strake, the hull needs to be made of several components ($$$$$). The complete moldings for a 50 ft sailboat may cost more than a million dollar. But they can be used for building many boats.

Thats the reason, why GRP one offs are normally build with the positive method. A plug is build out of wood and the GRP hull is laminated onto this plug. But this means, the outside of this hull has to be sanded, faired and painted like a steel hull, whereas the GRP hull comming out of a mold is completely ready, because its outer layer is the gelcoat. And a hull build with the positive method is less accurate than a hull build in a mold, but this trade off is acceptable, because it is much cheaper.

Modern welded steel hull building is very cost effective. CAD plans of the spars, stringers and skin sheets are directly transfered to the computer controlled plasma cutting machines and the welding of this most accurate pieces of the puzzle will only take a few days at max. No mold or helling is needed anymore. Even the bending of the skin plates is done by computer controlled machines.

The rest of the boat / ship building, is almost the same for all types of hull material.

What I am missing in this discussion is the building of hulls made of Aluminium. Todays marine grade aluminum, especially the high quality material Alustar, makes very strong and long lasting, high quality hulls. Due to modern coatings, corrosion on Aluminium hulls should be no issue. The superstructure of modern large yachts is made of this material anyhow. High end megayacht builders like Royal Huisman are building exclusively in Alustar.

My personal conclusion would be: For a sailboat or displacement hull (one off), I would always opt for a welded steel or Alustar hull. GRP or even better cored CRP / Aramid, I would only choose for racing or very high speed vessels, where weight saving is the major concern. GRP hulls are the solution for production boats, where the costs of the mold can be spread over many hulls.

There are very few (if any) FRP boats of good size, say 50'+, that are delivered to the end user as it came out of the mold. Visit any production boatbuilder, and they all have a touch-up/rework station, and every Gelcoated boat gets some extra cosmetic rework beyond the typical polish/buff.

It is a myth that molded GRP boats produce a customer ready exterior finish without the need for touch-up.

That is more or less self explainatory. But there is much less work to do, than fairing, sanding an painting a GRP hull made via the positive method. Plus the plane gelcoat is not ready for the sea. Normally a blocking primer and the antifouling is added to the lower part of the hull. The better the bold, the better the hull comming out of it.

Here is a link to a nice website of THE prime sailboat producer in Sweden, Hallberg-Rassy. It explains their production process nicely.

(Hallberg-Rassy - Old site)

Seems pretty steep for just three molds - Hull/Liner/Deck and some small hatches. How many units are you going to have to build to amortize the $1Mill before you see a profit?

Costs of a mold

Remember, we not talking about molds build in China or Taiwan for some motor vessels. We are taking about highly accurate, high precision molds, build in Europe or the US, for high end sailing yachts or fast boats. And they concist of more than just 3 pieces. The production of a hightech plug, using 6-axis CNC milling machines, costs a fortune itself. Then the mold of a complex hull may concist of 3, 4 or more pieces. The same counts for the deck and other parts of the boat. Some of those molds are heated / cooled for the controlled hardening of the cored GRP / CRP material. The molds are heavily reinforced for stability and stiffness. And those molds have to be build for safe operation in the molding process. It is not acceptable, that a mold brakes apart, when moved or lifted (as has happend in China) and kills workers. And finally, some of them last for more than 100 hulls. The pay off is a high and constant quality, fast and strong hull. And those boats are not cheap either, because the rest of the boat is also high quality . For a lot of Med based boat builders, their molds are the highest value assets of the company.

picture of a Hallberg-Rassy 55

I have seen plenty of accurate precision molds built with the same CNC machines in the states and overseas as you may have in Europe. Somehow, you assume that these manufacturers can not build to the same level and precision of a 50' sailboat builder (which is really not all that complex geometry to begin with) in your neck of the woods.

So let's throw some numbers around for your 50' example - let's say the hull is about 1000 square feet, the deck is about 750 square feet and the liner is another 750 square feet. At a minimum of your $1Mil US, that is $400/sf plus small parts. I know there are plenty of CNC shops that would jump to sell you tooling at that price, seems over-inflated, regardless if it is a 2-piece/3-piece or whatever piece mold.

I have seen many non-steel reinforced hull molds pull more than 100 parts, so I don't see that quantity as holding any particular milestone value.

Regardless, my point is your Million dollar estimate seemed rather high for a production builder, unless you have seen those numbers for yourself.

And like I said before, regardless of how straight/precision that tool is, the Gelcoat finishfor a 50'+ vessel will still require hand work (I am talking above the waterline) before the dealer/customer get ahold of it. Check out the production boatyards, the air-driven DA sander is their best friend!

Production costs of a mold

Sorry, that you took my little hint with the mold building in China or Taiwan personally. And just to confirm, I concider the United States on the absolute same quality level than Europe, in almost all industrial branches (Except for some cars maybe ) and even much higher in the aviation or aerospace industry.

At first, I do not mean the type of mold construction with the plug building via CNC milling. Any company, in any reasonable civilized country in the world, should be able to build a perfect plug out of high density foam blocks with one of those hightech CNC milling machines (provided they have the data). As far as I know, on some Far East boats, all the data came from the States (Dana Point, Palm City ?) or from Naval architects in the Netherlands (Vripack). I do mean those average plugs, build with the old method of wooden frames and skin, build upside down by a lot of little hands. One of those plugs is hardly as acurate as the other type.

Second, in Europe, the high end industry has to calculate with costs per manhour of app. 100,- Euros or more. We are talking about costs per hour, not per day, week or month !!

Third, the safety regulations, the enviromental restrictions, the laws concerning labour and social wellfare are much more restrictive and far more costly for companies in Europe or the US, than in the Far East. That makes tooling and prototyping much more expensive.

Fourth, there is always some cleaning, sanding and polishing of gelcoated hulls, when comming out of the mold, but complete sanding and painting of the gelcoated hull, like I have seen myself in China, is normally not necessary.

Fifth, I am not arguing about a few dollars and yes, I have inside knowledge. But 500.000,- to 750.000,- Euros for a hightech, highprecision, longlasting and complex production mold system from start of design (of the mold) and construction, until the first production hull is comming out of it, is pretty close.

And last, I have expressed on this Forum several times, that I like the quality and the design of Taiwan or Chinese build boats like Horizon or Nordhavn and even more than some Med build boats. We were just talking about the costs of the mold, not about the builder.

Cheers

Thanks for all the good data and thanks for sharing, you are insightful as always.

But I will take the full estimate of a production mold system with a grain of salt - @ 100 euro/man hour, that is a lot of overhead/carrying costs/profit already built-in, as I am sure that no yacht mold maker is pulling down over $250K US in Europe, if so, I would expect a mass exodus of US boat building folk across the Atlantic. Even with the generous 38 hour work week/bank time/7 weeks of vacation in Europe that does not represent the actual cost of tooling, but has already been filtered by those wonderful controlling people in finance.

In my travels to production builders in the states, I rarely (if ever) have seen a production molded hull (50+ feet) not get a high degree of sanding/polish/buff, and have seen plenty of re-sprays. Sometimes it is easier or a time saver. Most consumers are not aware of the total effort to get today's yacht quality showroom finish, but the committed builders do whatever it takes.

I have even had a few discussions with the good guys at Hatteras, who continue to spray LP pn all their molded parts, and the prevailing theory (from discussions with their competitors and the custom SF guys) is that the gelcoat guys put about the same labor into their molded gelcoat hulls (after pulling the parts) to arrive at the same level of finish as their post mold LP spray work. That and a loyal following has kept them from changing over to a more "conventional" process.

It is not an easy job to be a high end yacht builder in those high-wage countries in Europe .

Maybe my command of the Enlish language is causing some misunderstandig. The costs of labour (manhour) does not necessarily reflect the income of the specific worker. The overhead (what we call employee on costs) is much higher than the amount of money the guy on its workbench gets payed after the day.

And here the statutory and official requirements concerning safety and polution are very expensive. If I compare the open sheds, I have seen in China (both Taiwan and PRoC) and the circumstances, people have to work in there, with the hightech production buildings here in Europe, with there climate control systems, air excavation systems, air filters, noice reduction and other safety measures, boat building in Europe is very expensive. I wonder, what a Nordhavn or a Horizon boat would cost, if completely designed, tooled, manufactured and equipped in Europe.

Do not get me wrong, I believe, the production method and company setup of PAE is the absolute best way and of building yachts of constant and reliable quality in Asia. Even better than Horizon or Jade Yachts, because both are completely Taiwan based, owned and controlled companies. Horizon was on the same level than PAE, when still affiliated with Drettmann. Today, a customer has to organize most of the Drettmann part by himself. You dont have to, If you trust your (builder dependend) dealer.

I am unable to recall the calculation facts of Asean Yachtbuilders, but a Korean or Chinese Shipyard will sell me an average Cargo ship (Container, Tanker or Multipurpose) for less than 50 % of the basic production costs of a German ship yard. A German ship builder told me, he could not buy the steel for the final price of a Korean build cargo vessel. I know, those yards are heavily subsidized by their governments, but it is still unbelievable. The only way our shipyards can survive (if they will at all) is admost quality, flexibility and cutting-edge technology.

As far as the final touch of GRP boats is concerned, here in Europe we have have both parties of this approach. We call them the Awlgrip and the Gelcoat communities. Most builders, which were bought by strategic investors, have changed to the "dark side of the force", to the Awlgrip party. Their production methods have been optimized towards higher profit margins, friendly spoken. (b.t.w. Awlgrip means the boat is completely sanded, faired and painted after popping out of the mold, by using the Awlgrip coating process and materials).

But I am still a big fan of Aluminium build and Awlgrip coated (or Sikkens) boats

If you mean cost to the customer, probably close to the same, the difference is the marketer's profit. The difference in production cost goes in the trade name owner's pocket.

Without trying too hard to avoid politics and social stuff, you don't need to wonder what the cost would be, look at the costs to the nation for NOT designing, tooling, and manufacturing those boats in Europe or the US.

That conversation contained their opinion, not mine. I am sure it has come up several times before as they struggle to find ways to make their product more profitable, and one of the topics was to consider a Gelcoat process vs. LP. They obviuosly have not changed.

Here in Europe, we lost some of the highest quality boatbuilders over the recent years. Not because their boats were not good enough anymore, they were (and had to be) just to expensive. Those little yards, which used to build two or three masterpieces of boatbuilding per year, are mostly gone. And on the other hand, one has to admit, that the greatest artist in boat building does not necessarily has to be (and was) a good salesman. If I remember those names in Germany, like Burmester in Bremen or the little company Dübbel & Jesse on the island of Norderney, they have made some boaters eye shining, when one of their boats was passing by. I believe every country in Europe or the US had those great names, which disappeared over the years.

The globalization has changed the industry. Profit is made by numbers, not by quality. And by more and more great names, sold to the strategic investors or the Chinese, the quality of boats will decrease even more.

STEEL HULLS with Composite Superstructure / Topsides

I was just preparing to start a new subject thread, when I discovered this one via a forum search for “steel”. I see here that both glass and steel are discussed simultaneously, and in good fashion. So I've elected just to add my conversations to this existing thread. Pardon my 'introductory wording' as it was originally written to head up a standalone subject thread.


STEEL HULLS with Composite Superstructure / Topsides

Let me preface this discussion with this; I come primarily from the Multihull ranks, and steel boats have never really been a contender as a building material for these vessels,.....just too heavy. So my knowledge of steel boat construction is limited, and that might become apparent in some of my postings, particularly some out-of-the-box thinking I might suggest.

Steel boat construction has come to my mind recently as I review 3 older boat designs that I have identified for a 're-design' (modernization) possibility. In all 3 cases these are monohull displacement vessels, and therefore are candidates for steel hull construction.

Why steel? Its an inexpensive material, easily fabricated, and very durable for worldwide cruising. It's a material that inspires confidence in a boat's survivability from mishaps and collisions by both experienced boat owners and newly minted ones.

Why a new steel subject thread? As the thread title indicates I wish to explicitly explore the combination of a steel hull with composite superstructures. Naturally I want to review and cross-reference to those other good discussions on the forums dealing with these two construction materials,....steel & composites

....Why Steel?

I did very much like this quote from a posting back in 2004

Composite Superstructure Considerations

There are any number of notable ship constructions where a lighter-weight superstructure has been sought out for a basic metal hull. Alum topsides over a steel hull comes to mind for a number of larger yachts and navy vessels. Creative bonding techniques have had to be invented for these cases. Likewise the joining of composite superstructures onto steel hulls requires creative thinking about both the mechanical and the 'chemical' bonding of these two very different materials.

I use the word 'chemical' in the sense of adhesion. There are any number of mechanical methods of bonding that are conventional in manner. It's the adhesive bonding that is continuously under development with ever-stronger, greater adhesion products. I think we are currently at a point that we have a number of very good adhesive products that can join our composite superstructures to our steel hulls with extreme confidence.

My thoughts are this 'transition' from steel to composite should take place at the hull-to-deck interface, NOT at the deck to cabin superstructure joint. In other words I favor a composite deck, ...more specifically a sandwich-cored composite deck onto which the rest of the cabin/superstructure is attached.

I've witnessed years and years of sandwich cored composite constructions. Basically it boils down to using 3 types of cores; 1) balsa, 2) various foams, and 3) honeycombs of either alum, Nomex, or polypropylene. Generally the balsa cores have won out over the foams for deck fabrications due to their greater stability under the extremes of tropical heating. But balsa cores have a significant history of susceptibility to rot from water penetration at various hardware attachments and migration of water along the core-to-skin bond line.

Alum & Nomex honeycombs are a little pricey, and extra care must be exercised to obtain a good bond with the very 'thin edges' of the honeycomb chambers. Polypropylene honeycomb however has a fiberglass cloth scrim thermo-fused to its cell structure,...a very consistent bonding that doesn't provide voids for water to migrate across. This 'scrim layer' in turn provides a 100% bonding surface for the fiberglass skins to be applied to. And the polypropylene material itself is totally rot proof in the case of any water penetration.

I've come to the conclusion that this 'poly-core' material is the best choice for my composite decks and superstructures. Poly-core is one name the Aussi's and NZ boat builders term it. They actually pre-fab sheet panels (akin to sheets of plywood) of these materials in a controlled environment, and subsequently computer cut those sheets into specific panels that will be joined together to form a structure, a bulkhead, a deck section, a cabin side, etc., Here is one example
Polycore Composites - Polycore Australia - Polycore Honeycomb

NidaCore and Plascore are two polypropylene honeycombs better know in the American market. But neither of two produces have been reformulated into pre-fab sheets/panels for some reason?....perhaps not as great a demand for kit-boats here in the USA? It could be easily done though if there were sufficient demand

For reference here are a couple of other pre-fab panels utilized by these kit boat designers, Duflex, Durakore. But these panels utilize balsa or foam at their cores.
Boat Construction | Lightweight Building Panels | Architectural Panels
DuraKore® - ATL COMPOSITES


....and some of my confusion about the nomenclature
Are Cats Made from Duflex Panel Kits Strong ? - Page 7 - Cruisers & Sailing Forums

…. a recent private note I received from an experienced steel boat builder

Dear Sir,
First off I appreciate any and all input I receive from experienced steel builders

I must take issue with this portion of your reply, “GRP in all its forms are much cheaper and easier and faster to produce.”

This might be true in a large volume production situation, but for a low volume quantities (might be termed semi-production) the cost of plugs and molds for the GRP boat must be factored into each vessel's cost of building for at least the first 10-15 units built. The cost of those plugs and molds can be considerable in both time and materials, and if you seek to hold to a price point on your finished vessel, it could take the builder 2-4 years to recover their 'tooling' investments.

Furthermore if a firm anticipated offering a particular vessel design in a 'kit form' for some private clients, or a remote builder in another part of the world, the traditional 'GRP mold method' does not make sense.

Fiberglass building materials have also increased dramatically in the last several years,...along with oil prices. Couple this with the skill of labor you really need to properly build a composite vessel, particularly a hi-tech sandwich-cored one, and you begin to see a competitive edge for alternatives.

I've chosen to consider this alternative of steel hulls with prefabricated panels of cored composite panels for the decks and superstructure. With the advent of computer-cut steel panels and computer-cut composite panels, the
1) time required to build the basic shell of the vessel might be significantly reduced
2) the skill of the labor to perform this portion of the built might be less
3) a kit form of the basic vessel could be shipped to a private buyer, or another sub-production facility anywhere in the world.

Some have asked, 'why not an all steel vessel rather than mix in composite structures'?? As you pointed out in your note above, the steel decks can be more problematic than the hulls. Neither the steel decks, nor the steel cabin sides/structures are by nature insulated. Also one must add in a substructure (battens, etc) to these metal skin panels to both get a decent attachment for the interior finishing panels, and to get a non-moisture condensing, insulated interior. The cored composite panel decks and superstructure are already self-insulating and non-condensing by their nature. As a bare necessity the inner surfaces of these composite panels could be simply painted a pleasing color, or a decorative wall covering fabric glued on.

So lets summarize at this point. I have 3 different vessel designs in the 40-60 foot range that I feel could have moderate to good success in today's yacht market. But of course in the interest of being cautious the plan is to NOT over-extend ones self with a BIG investment in plugs, molds, tooling for any one of these designs.

A steel hull shell fashioned from computer cut panels that would be assembled in a external jig/frame (reference 'frameless steel construction') appears to be fairly 'quick and dirty'.


This steel shell could then be reinforced with the traditional bulkheads, frames and stringers all welded in,

…....OR, it might well be 'framed up' with composite sandwich members that would be glued in! These 'internals' might well eliminate a considerable amount of welding that is both time consuming, and that distorts the hull plating in many metal boats. Those distortions subsequently result in a lot of 'fairing work' being required for the finished hull.


…..Sorry for this rather dis-jointed posting, but I thought but I thought I had better go ahead and make this additional posting to encourage the traditionalist (and naysayers) to take a little more time to reconsider some 'out-of-the-box thinking on steel hull construction. I have some more surprises.