Brent and I have debated this around the web probably for at least a decade. This is from some of the earlier discussions on this topic.
Build time and cost: While it is true that you can tack weld a steel hull very quickly using an 'origami' technique, if you compare the overall build time with welding, finishing and constructing an interior to an equal level of finish, in prior analysis that have been posted previously on other sites where we have debated this in the past, other techniques require similar cost and time to build, which is especially true since steel prices have ratcheted up relative to other materials.
If time and money are the prime determinants, in the size boats that we are taking about, then stitch and glue sheet plywood sheathed in epoxy and glass inside and out would easily beat steel on cost (and on strength if of equal weight). The time is greatly shortened on either Orgami boats or on plywood boats with accurate cutting patterns for the interior bulkheads and hull panels.
The Steel vs. Fiberglass hammer argument:
This is a favorite of the steel guys which says steel is better than glass because a steel hammer would damage a glass boat.
Again, I will refer to my previous analysis on this one. Start with the hammers, to begin with we need to compare hammers of equal weight and weight distribution. In other words, for example, to maintain that weight distribution, we need to compare say a 20 oz framing hammer made of steel to an fiberglass hammer of equal weight and weight distribution. The fiberglass hammer would have a head nearly 2 feet long and 3 inches in diameter. If we use the laminates that I have advocated in the past, I would use the vinylester resin typically used in bullet resistant military and crash helmets and a kevlar laminate in the actual impact areas. The impact resistance of that hammer would be several times greater than the steel hammer.
Then we need to look at the steel and glass that we are beating up with these hammers. In a past analysis that I posted on the Origami website, I had calculated that a fiberglass panel able to stand up to a 20 oz framing hammer would be somewhere between 3/16" and a 1/4" thick if the panel size was limited to around 2 feet span. If we compare that panel to a steel panel of an equal weight steel, the steel would be just a tick thinner than 5/100's of an inch (.05"), in other words something slightly thinner than the thickness of steel sheet metal used for body panels on a modern automobile. I'll take the equal weight fiberglass hull and steel hammer any day over the 20 oz. fiberglass hammer beating on an automobile body panel.
It comes down to the same thing here as well. Again we are talking about equal weight boats of steel, fiberglass and engineered laminate over cold molded plywood.
Lets start with the problem at hand namely the equal weight part of this sentence. If we compare the relative density of the materials involved, they are as follows: Steel= 7.85, Fiberglass= 1.92, and cold molded construction= .45 (3/4" port orford red cedar strip plank with two diagonal layers of 1/4" port orford red cedar veneers and a final longitudinal layer of douglas fir with an exterior laminate of vinylester resin and kevlar with minimal non-directional glass), So if we start out with a 1/2" thick fiberglass hull, the comparable weight steel hull would be something less than an 1/8" thick (roughly 3 MM), and a cold molded hull would be roughly 2 1/8" thick. And when the numbers are run, the fiberglass hull would have slightly more than 4 times the bending strength and roughly double the impact resistance. The cold molded hull would have nearly 11 times the bending strength, and somewhere between 3 and 4 times the impact resistance of steel.
Again, in a demolition derby, I will take the other materials over steel any day, especially when you consider how little steel would be left out of 1/8" plating after a decade of rust.
And as you noted the last time I posted these numbers on another website, if I remember correctly, your hulls are typically 1/4" and 5/16" plate. If we compare a 5/16th steel plate, to equal weight fiberglass and cold-molded hull panels, the fiberglass hull would be nearly 2 inches thick and the cold-molded hull would be 5 inches thick. The strength ratios remain the same.
I come back to my original contention, that of all of the materials that one can build a boat, on a pound for pound basis, steel is one of the weakest materials to build a boat, and if maintained in an equal fashion to the other materials, over the life of the boat, according to all studies that I have seen, a steel boat is one of the highest lifecycle maintenance forms of construction that one can chose.
But in the end, little of that matters, in sailing we make choices based on our goals, fears, and sailing venues. For some steel make sense. For most, there is little logic to owning a steel boat. The above was intended to illustrate the relative strength of materials by weight. I chose to use panel thickness as clearest way to illustrate basis of my comments on the relative strength of materials by weight. In the example, the greater thicknesses of fiberglass and cold-molded construction result in strengths that are substantially higher than comparable weight steel.
But as sometimes noted, no one would build a boat a boat this size with panels as thick as those in my example. But if you reduce the panel thickness and the strength of the panels equal to steel, you end up with a hull thickness that is closer to normal practice. In that case, you can still achieve equal strength to steel, but a very significant reduction in weight. And that is my primary point.
I don't disagree with Brent’s argument that "The truth is that steel puts a great deal of strength and toughness into a compact package” but I add that this strength comes at the cost of significant weight. In fact, more or less that is my key point. I raise this point in reference to someone considering custom building a boat with concerns towards the relative strength of the material being chosen.
The steel guys like to ask questions like; "Why don't they make icebreakers out of fibreglass or wood?" but to answer that question, until the early 1950's icebreakers were typically sheathed in Ironwood. Since then specialized steels have become the norm. As I have mentioned in prior discussions, steel really comes into its own as a vessel gets larger. When you talk about a vessel the size of an icebreaker, the compactness of steel becomes a significant advantage. Also Commercial vessels tend to be short lived compared to yachts. Beyond that, when you talk about an icebreaker, high weight is an advantage rather than a disadvantage.
Lastly, I am in agreement with statements in other discussions that, "Steel is certainly not for everyone, but neither is fiberglass, nor cold-molded wood." That is essentially the same point that I was making in my conclusion, "In any event, in sailing we make choices based on our goals, fears, and sailing venues. For some steel make sense. For most, there is little logic to owning a steel boat."
Wow! What a collection of disinformation, misinformation, and outright falsehoods in that post!
I use 3/16th plate not 5/16th in my boats, which weigh considerably less than a Hereshoff ,Atkin or many other cruising designs in the same size range. You claim that there would not be much left of 1/8th plate after ten years?
If that is the case, then the thicklness of my current boat, made of 3/16th plate, 29 years old, must be a negative value! Actually, except for the odd paint chip, the steel and paint job are as good as it was 29 years ago, inside and out, with an hour a year maintenance. I read in a metal boat magazine about a couple cruising the tropics, who couldnt get paint to stick behind the head due to it being always wet. It took 15 years for corrosion to go thru constantly wet 3/16ht plate ,in the tropics. Dont get your advice on steel corrosion on a boat from someone who has never owned one. They have no idea of what they are talking about.
Steel prices did rise, and have now fallen, to near what they were over ten years ago. The steel for the basic shell of my 36 is around
$9k. Try buy the resin and fibreglass materials to build a hull, decks, cabin, wheelhouse, cockpit , keel, rudder, and skeg for a 36 ft fibreglas shell for that much! The left over scraps, around 4%, make up your anchors, woodstove etc. Your cleats, instead of costing $40 each from a ship swindlers cost $1.80 a pound from the scrapyard, and once welded down with a dollars worth of rod, will never work loose or leak. Ditto your self steering, anchor winch, fittings, etc etc
A friend priced the fibreglassing materials for a 26 ft bristol channel cutter at $12,000, when I was building a 31 for $3,500. The ratio is the same today , as oil prices have not exactly been static since then.
When I was able to get a 36 ft shell together for around $8K, the cheapest commercial builders were doing it for was $25,000. Colvin estimated 1,000 hours to put a hull and decks together, using his outdated methods, something I do in 100 hours. One has to question the math skills of anyone claiming that 100 hours is the same, and costs the same as 1,000 hours!
Your 20 ounce fibrglass hammer will do zero damage to 3/16th plate. To get something closer to pounding on a sharp rock , use the claw end of your fibreglass hammer on a piece of 3/16th plate. It will do zero damage befoe disintegrating. .Then use the claw end of steel hammer on your fibreglass. The fibreglas will disintegrate. Then try it on your epoxy cedar combinatioin. "Reality at last!" So much for theory!
Wood has a tensile and compresion strength of 1,500 psi, steel 60,000psi , 40 times the strength to weight ratio. How many fibreglass boats in the same weigh range as mine have survived 16 days pounding on a Baja leeshore in up to 12 ft surf? Mine has. How many have survived pounding across 300 yards of Fijian coral reef and been dragged back across it with no damage? Mine has. If your calculations say otherwise ,then your calculations are obviously wrong, and clearly missing a factor..
Steel can stretch to 1.4 times its lenghth with out breaking. Tie a knot in a piece of steel wire. Then try the same with fibreglass. That is the kind of toughness other, more expensive materials simply dont have.
So bring me a cold molded boat roughly the same weight as mine, and lets have our demolition derby. I could sail right thru yours with no dammage whatever to mine . Theory and reality are light years apart, based on decades of expereince, pounding on lee shores, steel barges and ice, not on juggling numbers in an office.
The logic in owning a steel boat is in not having to worry about hitting Fukashima debris in the night and losing your life and that of your crew and kids in the night . Had the Sleavin family been in a steel boat ,none would have died . Discouraging people from the wisdom of choosing the greatly enhanced safety of a steel hull for offshore cruising, is life threateningly irresponsible.
I would recommend anyone considering offshore cruising, read Moitessiers book "The Long Way" and compare how trouble free, and failure free his circumnavigations in the roughest oceans of the world, in an industrialy rigged steel boat compare with any similar voyages made in fibreglass or wooden boats, rigged witrh trendy yachtie gear.