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Old 07-20-2013
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Re: Pros and cons of steel sailboats

Smack,

A few days ago, you asked whether anyone on this thread had ever considered building a steel boat. I had relatively seriously. There was a time in my life when I almost always had ideas in my mind for the custom boat that I would design and build for myself, at least in that moment. Some of these musings never got beyond the simple sketch stage, while on others I would develop in a high degree of detail and might even put together detailed drawings, calculations and a detailed estimated cost of construction.

I had first become aware of steel construction when I was running the drafting room at a naval architect's office designing an ocean going tugboat. Then when I worked for Charlie Wittholz, I was exposed to steel construction as it related to yachts. Charlie was a master at designing ‘deadrise’ sail boats (single chine) so that the chines looked right whether above or below the waterline. It started me thinking about steel as a building material. Probably 4-5 years earlier I had designed a small 26 foot MORC boat which designed with sheet plywood bottom, topsides, and decks, but with radiused cold molded chine.

I had previously begun to design a 40 foot version of the smaller MORC boat to be constructed the same way as the MORC boat with epoxy and glass over a mix of sheet and cold molded plywood. I had gotten far enough to have priced out construction of that boat. After seeing what Charlie was doing with steel, I began to adapt that design to a roughly 40 foot multi-chine steel boat, which was a stretched version of the MORC boat but with an extra panel instead of the radiused cold molded chine on the wooden boat. (To imagine this think of a stretched Express 37 hull executed as a muilti-chine steel hull).

I was actually a pretty fair welder at that point. Years earlier I had done a group project in architecture school in which we designed and fabricated a small steel bridge. That course included a chance to take a welding course at a vocational school which I opted to do. I had gotten good enough to weld the light gauge steel tubing that I used to build the frames for the motorcycles that I raced in my 20’s, and so thought with some practice and a bit more instruction I could get my welding skills up to a point where I could weld up my own hull.

This design did not follow the origami concept per se, and the deck and house were glass over wood to save weight. The hull plating was steel, as was the internal framing. In terms of framing, I had planned to have some transverse frames or partial bulkheads at the forward end of the vee-berths as a kind of collision bulkhead, three in the area of the keel attachment, mast, and at rig load points, another near the engine mounts and in the version with the skeg-hung rudder and internal rudder post, at the skeg. (There was an outboard rudder version which did not have the aft transverse frame. I also planned to have longitudinal flat bar on edge frames near the end of the chines and on either side of the bilge. I had gone so far as to create ‘nesting plans’ showing how the parts would fit on the steel plates to minimize waste. And then I priced the steel and the protective coatings . At the time the cost numbers came back very high compared to the numbers that I had for the wooden/glass composite version.

But the steel hull was also substantially heavier than the wooden hull (maybe 30%, which added roughly 10-12% to the overall weight of the boat). In a value engineering exercise, I began doing comparative structural calculations to see whether I could use lighter steel panels, or whether the wooden panel thicknesses were too thin and therefore needed to be beefed up. What also surprised me at the time was that wooden hull was actually stiffer and stronger in bending than the steel hull even though it was lighter.

At that time, I was not able to do impact studies so I assume to this day that the steel version would have had greater impact capacity and certainly would have had better abrasion resistance than that particular composite of wood and glass. I had a chance to discuss this with Charlie at some point after that and it was his sense that the weight disparity was less as the boat got larger so that at some point over 45 or so feet steel became more compelling as a building material.

For all kinds of other reasons, I never built either boat, but I have owned a number of FG boats that I could daysail, race, and cruise and have done so continuously ever since.

I also want to talk a little about my views on Brent’s work. While I agree with Bob that Brent does not seem to have done the math to back up his designs, I am not sure that bothers me. What Brent describes as his process is very similar to what traditionally happened with the evolution of working water craft. By and large, working watercraft were never drawn up. Builders would make small scale models by eye, and the take measurements off of those models. These were experienced builders and they would draw on their experience from one design to another. They would also tweak a design toward something they expected would improve the design. Sometimes the boats were better, sometimes not, but with each iteration they learned what worked and what didn’t and improved their designs.

In that regard, what Brent has done over the years, follows in the footsteps of very venerable tradition. I would be the last to criticize that tradition.

But within that tradition, there was also an understanding that in the absence of formal weight studies, there had to be reliance that these vessels would be operated by knowledgeable skippers and crews, who would load them in a way that the ship sat properly on its lines, with ballast and cargo shifted to accommodate the changing loads.

I respect the inventive details on his boats, which cleverly employs ‘found objects’ to produce simple, inexpensive (ignoring the value of fabrication time for the moment) and functional solutions.

If Brent merely said, ”I follow in a working water craft tradition of trial and error design, using workboat levels of finish and that is all I and my clients aspire to. There have been a bunch of boats built to my designs that have operated up to expectations. For one off designs they were moderately quick to build and reasonably cost effective.” I would respect that and understand how that fits into the broad range of options out there.

Where I suggest that Brent goes off the rails is when he claims a universality to his thinking suggesting that everyone would be better off with one of his boats for the reasons that he and his clients prefer his boats. He denies that other people may have values different than his own which is get out cruising quickly while you are young. (While I have no gripe that this is in fact the right answer for some people, I also think that others of us might actually think that a life well lived needs to be broader than that, and may actually prefer to be a part of a shore side community, contribute to society, and perhaps have families or that people may actually value aesthetics and craftsmanship.)

My other gripe with Brent is that he denies the value of science and engineering, and makes claims which are dubious at best, without the ability to provide real data to back up his dismissals; providing instead non-symmetrical arguments (i.e. comparing the strength of a purpose built, one off steel boat, to a value oriented glass hull) or hyperbole filled anecdotes intended to be a metaphor for real life (i.e. the ability of a 5/16 steel plate to stop a bullet vs. a fir stump, which ignores that the real comparison is a low speed impact and a comparison between a 3/16” steel plate, and a equal weight composite with Kevlar skins and nearly 2 3/8” of wood behind it. )

Unfortunately, all that said, I suspect that Brent and I are close to the same age, and that at our age nothing any of us say to him is going to change his thought process or point of view, nor is he likely to change mine. We have been trading jibes for what must at least 15 years and a bunch of forums. Over the years I have put up speadsheets showing the data and assumptions that I have used as the basis of my positions, with Brent usually responding by calling me a liar, denying the science, or countering with some irrelevant metaphor. At this point I must admit that I view Brent as being in the unenviable position of Monty Python’s Black Knight, insisting "'Tis but a scratch", "I’ve had worse", "It's just a flesh wound!" and finally, “All right, we'll call it a draw."

It’s not a draw….its a shame.

Jeff
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Last edited by Jeff_H; 07-21-2013 at 02:04 PM.
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