Steel vs Fiberglass - Page 2 - SailNet Community
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post #11 of 25 Old 01-02-2005
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Steel vs Fiberglass

right on billpjr couldn`t agree more.I can stand on a glass and I can stand on a tin can. Drop one on the floor and you can guess the rest.What the issue becomes is what doesn`t bend breaks.I have worked as a machinist for years so I probably sound one sided however the facts are the facts.
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post #12 of 25 Old 01-02-2005
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Steel vs Fiberglass

If the intended use of a boat includes sailing in areas with pacj ice, then a steel boat is likely to be best overall. If however, you don''t plan to sail in areas where your fiberglass hull could be crushed, then fiberglass is likely to be best overall.

Surviving a hard grounding is something every captain tries desperately to avoid. Thus, I wouldn''t factor it into the equation of "best overall".

No doubt others have mentioned the pluses and minuses of each material. It seems clear the market vastly prefers fiberglass.

Therefore, I think that unless you like doing lots of maintenance (scraping and painting) or absolutely must sail through pack ice, a fiberglass boat will probably be the "best" choice for you too.

~ Happy sails to you ~ _/) ~
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post #13 of 25 Old 01-02-2005
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Steel vs Fiberglass

If we want to get into what the market prefers I guess we will be buying our boats from China with the rest of the things we buy.The market has been selling us junk but if it is cheap junk the vast majority of people will buy it.The only reason I sail fiberglass for cruising is simply I cannot afford aluminum.And before anyone jumps all over My choice with their personal reasons I am well informed with materials and it becomes economics.Fiberglass is still a good material for most people and like any of these opinions it is you that will be doing the buying.
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post #14 of 25 Old 01-02-2005
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Steel vs Fiberglass

dman I am with you on that one.

Fiberglass is simply the cheapest way to mass production boats, that''s why it dominates the market, cause it can produce cheap boats.

I am not saying fiberglass boats are bad and I agree with Jeff about not making sense to build steel boats under 40ft, but I am with you in what regards alluminium.

Do you know this one?

http://www.atlanticyachts.nl/

Paulo

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post #15 of 25 Old 01-02-2005
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Steel vs Fiberglass

nice stuff I just need to come up with 7 numbers tonight and I am set.Heading off to the corner store right now.
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post #16 of 25 Old 01-02-2005
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Steel vs Fiberglass

Jeff_H said: “You see these kind of anecdotal comments written around the internet but pound for pound, steel is not as strong as composite construction, or in other words, a composite boat of equal weight to Skookum would have been stronger than the steel boat. The perception that composites are not as strong as steel comes from comparing steel hulled boats to lighter weight glass boats.”

This is one of the few times that I actually disagree with Jeff. I think the statement that “pound for pound, steel is not as strong as composite construction” is also anecdotal.

In my experience as an Aerospace Structural Engineer this was the typical sale pitch for composites. We were comparing steel, aluminum and titanium with fairly hi-tech graphite epoxy prepreg composites and we often struggled to obtain equivalent strength. He is the reason. Metals are isotropic materials. This means that their tension, compression and shear strength are for the most part unchanged with changes in the orientation of the material. This is quite the opposite of composite. Actually it is one of the reasons that composites were developed, to orientate the material strength in the direction of the internal loads. This works great for certain structures and not so great for others. What often ends up happening is that a composite structure is laid up to develop pseudo isotropic properties. That is a lay-up of 0/90 and +45/-45 degree plies. This is only pseudo isotropic since the properties end up only being equivalent in the 0 and 90 degree direction. Also the transverse properties of a composite laminate are basically just that of the resin. This defeats many of the strength to weight advantages of composites. There is an additional factor which isn’t mentioned often about composites. The have quite a large strength reduction factor do to moisture absorption and elevated temperature.


So I guess to wrap this up, I think if you looked at advertised vendor data for unidirectional prepreg composites with out moisture and elevated temperature reductions, the strength to weight properties of most composites would blow most metals away. If you compared the properties of an assembled laminate with the proper strength knock down factors with metallic structures I think you might pick you material based on other characteristics (like durability, cost, ease of use etc) because strength to weight would not be an overwhelming feature.

Bill
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post #17 of 25 Old 01-02-2005
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Steel vs Fiberglass

I could have said all that but I didn`t,Yeah right.If I am ever designing a spaceship make sure you call me, my head is still spinning from that one,must have fallen asleep in that class.One hell of alot of information.Could you really simplify that for a good old country boy. good stuff thanks
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post #18 of 25 Old 01-02-2005
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Steel vs Fiberglass

As I have posted before....

"It is said among dedicated blue water cruisers in the South Pacific, 50% of the boats are metal; the rest of them are from the United States...."

Depending on fiberglass and composite hulls is like playing Russian roulette, especially in warm, tropical climes or anywhere near water.

CT~~~ Proud and satisfied owner of a 53'' Fast Passage ALUMINUM Cutter.
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post #19 of 25 Old 01-03-2005
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Steel vs Fiberglass

Dman,

like you and for the same reason I have a fiberglass boat, but the Atlantic 38 is not a 7 number digit boat. It costs around 350 000 euros, including 19% VAT.

The French are now beginning mass production Aluminum boats and the new Allures 40 cost around 250 000 euros and the Ovni 395 even less. I think that in a near future the prices of Aluminum boats are going to come down.

Paulo
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post #20 of 25 Old 01-03-2005
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Steel vs Fiberglass

First, it''s a shame that ''steel'' is the focus of this thread and that metal boats are mostly discussed generically, when in fact there is a great deal to distinguish aluminum from steel, both pro and con, including cost.

Second, let''s assume we have a magic switch that we can flip and which affects our ability to view boats thru-out the Pacific Ocean. If we flip it one way, it gives us a 40,000'' view of ONLY self-built boats sailing in the Pacific. Looking down, we would be able to see that a large percentage of them (tho'' perhaps not a majority) are going to be steel, with some others being wood or wood/composite and a still others being of other materials, including aluminum. Now we flip the switch in the other direction and can view only non-self-built boats: only a small fraction of them will be metal. Whether we like it or not, a fair conclusion to reach is that the choice of a metal boat is driven by factors other than the kind of sailing we plan on doing.

So rather than only talking about metal as a suitable material based soley - or even principally - on intended use, we could instead talk about metal as a likely choice based on whether a given sailor with Pacific ambitions, shopping in his/her marketplace, will either build or buy a self-built boat.

Does it make sense to self-build, based on the desire for a metal boat and given only a moderate budget? The summary comment below on the wisdom of deciding to self-build when choosing an offshore cruising boat, has been said before on this and other BB''s; I''m taking it from www.mahina.com simply because of its brevity.

"Home building makes the least sense unless you are an experienced boat builder and are not concerned about time and expenses. Home-built boats generally end up costing more than a well-built used boat, are usually much more difficult to sell when you''ve completed your cruise [and] frequently have a lower resale value than a comparable production boat."

BTW if we took our magic switch with us and did the same thing from 40,000'' over N European and Med waters, we''d find a higher percentage of non-selfbuilt metal boats. And you will note this is without the predominant rock & coral that supposedly justifies metal hulls, and also despite the cruising grounds being far more developed (nav aids, harbor berths, etc.) than in the Pacific. This is because there are more Euro yards building in metal, both steel and aluminum, to a very high level and because the Euro marketplace embraces metal more readily than elsewhere (e.g. North America).

Of course, all this is just cheering from the grandstands and boat buying is usually not driven by one''s ultimate materials preferences and ''some day'' cruising dreams. In truth, most cruising boat buyers start off with neither a firm itinerary nor much long-term cruising experience. What they do have is a rather firm purchase budget, a desire for a certain level of amenities and quality of finish, and they limit themselves to boats which are regionally available...which reduces the diversity of their choices in an absolute sense, but makes the logisitcs of the purchase easier. They will then pick from this subset of choices based on cost and preferences as stated.

Where there is a diverse selection of metal boats at more affordable cost - and where their acceptability/desirability is greater and they are viewed as suitable for the intended mission, metal becomes a more feasible choice in the real world of boat buying. But those places are niche markets, and its clearly a case of Mohammed needing to go to the mountain for most boat shoppers who want to consider a diverse collection of affordable metal boats.

Finally, I think it''s a fair statement to say that, when looking at metal boats being purchased over any given time period, most of them are going to be either self-built (to include finished out by the owner from a bare hull/deck) OR they are going to be relatively expensive relative to all boats of that size/class. If someone else''s project boat isn''t what you want, and you have a purchasing budget that is like the rest of us mere mortals, you will probably end up with a fiberglass boat, having chosen it from a relatively large, diverse collection of mostly fiberglass choices. There are exceptions to this statement and there is certainly some geographic variability, but not enough to impeach the general conclusion, I believe.

Jack
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