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  #1401  
Old 10-02-2013
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Re: Pros and cons of steel sailboats

Len:
Yep, it could be fun and enlightening I hope.
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Re: Pros and cons of steel sailboats

While there has been a lot of interesting give and take in this tread, I must admit that it concernrs me a little that this thread has gone so far off the rails. This seems like a very worthwhile topic which could be a simple and linear dialogue on a moderately complex set of discussion points.

Instead, it has become the proverbial equivalent of the Tar Baby, clinging to whatever relevant or irrelevant issue it touches and dragging that issue along for often many semi-vitriolic pages at a time.

If SailNet was not the online equivalent of a waterside bar, it seems like it all should have been a lot simpler than this. And while it can be seen as inevitable that life style and economics figure into almost any conversation exploring alternative ways of going cruising, this thread has picked up more than its fair share of effluvia.

I do think that within the off-topic aspects of this discussion there are useful insights into how various sailors view the sport, and more specifically cruising. I think that it is useful to see these contrasting views of sailing and cruising and understand the seemingly broad range of viewpoints from distance cruising is the sole appropriate end unto itself, to views of sailing and cruising as a merely an adjunct part of a life well lived.

Within this thread there are similar debates about performance, survivability and aesthetics, with individuals claiming theirs is the one universally right position. (At least from my point of view, there is no such thing as one universally right way to enjoy sailing and cruising and that each individual gets to define their goals, tastes, fears, pleasures, priorities, budgets, and so on. And the only wrong answer is when that individual makes a decision that is at odds with their own defined preferences. But that’s another topic for the next thread.)

But that aside, I thought it would be useful to gather the points which address the basic subject of the Pros and Cons of steel construction as well as some of the related subjects. And drawing on the old political saw that every one gets to have their own opinion but no gets to have make up their own facts, I also think that there are a lot of ‘facts’ within this thread and a bunch of opinion being presented as fact.

If you weigh through the ebb and flow of these 1,400 or so posts, there are actually quite a few really good points about the pros and cons of steel construction. And while not everyone will agree on all of these points, I thought it might be useful to try to summarize the main ones (at least the ones that I agree with anyway). I also apologize that this is absurdly long and that I cut and pasted much of this from earlier discussions.

Pros:
Steel Construction in general:
 Steel offers a lot of strength in a very small volumetric area. This allows a comparatively low volume for skin and framing, and so more useable living space and storage space within the shell.
 Steel offers a tremendous amount of abrasion resistance.
 The materials for a steel hull can be purchased relatively inexpensively.
 (Assuming that the boat builder can deal with inclement weather) A steel hull can be constructed out in the weather saving the costs of leasing a large space to building.
 If a ‘work boat’ style finish is acceptable then finishes can be relatively inexpensive and should be fully within the range of skills of an amateur.
 Steel construction permits the fabrication of robust integral fittings which in turn minimizes the opportunity for hull and deck leaks. This is especially true if a steel deck is used since the welded hull to deck joint results in an effectively monolithic connection.
 An amateur with good welding skills and access to a decent quality welding and steel handling equipment can fabricate his own boat.
 Repairs to steel hulls can almost always be made in a manner that restores complete structural integrity.
 Steel boats are nearly infinitely re-buildable.
 Steel does not have an inherent structural load path orientation and so can disburse and absorb loading equally well in all directions. This is especially useful in impact loads which tend to occur in random directions relative to the normal service load paths.
 Steel has an inherent ductility which allows it to deform rather than puncture in an impact.
 Small steel vessels (perhaps under 40 or so feet) can be constructed essentially monocoque, with a minimum of framing, doublers and/or other forms of reinforcing. This is a bit of a trade off since omitting framing requires addition skin thickness and potentially results in greater overall weight. As boats get larger, the concentrated loadings from the keel, rudder, and sail plan loads become exponentially larger relative to the skin loadings, and so at some point knees, bulkheads, and stringers become critical to distributing these loads into the skin.
 The ability to weld together various boat components, and steel’s ability to deal with a pretty wide range of temperatures offer construction options such as pouring lead ballast right in the keel cavity, or having integral engine cooling water heat exchangers that are integral with the keel or hull.

Neither Pro or Con;
 Steel durability requires proper protection of the steel from corrosion. This is especially important on the interior of the boat and in high wear areas. Brent outlines his methods for prepping and painting the interior of the steel and describes a very long life span for that approach. But Brent also notes that almost no steel builders besides him do it his way and so based on Brent’s experience, corrosion problems in steel boats from other builders are much more likely to be problematic.
(My experience with older steel boats is that they have a comparatively short life. When I worked for Charlie Wittholz, I worked on drawings for a steel power boat. Charlie’s standard spec’s called for the interior of the boat to be sandblasted ‘white’, coated with a zinc rich epoxy, and then coated with several coats of coal tar epoxy. The interior of boats to within a foot vertically of the bottom of the turn of the bilge were then sprayed with closed cell foam. 20 years later that boat showed up in Annapolis. By then, the owners had replaced much of the bottom plating since it had rusted to a point where it had failed survey and there were still areas that were rusted (from memory) to less than approximately 1/8” of material remaining. There were several differences between the construction of this boat and the Origami boats in this boat was hard-chined and had transverse and longitudinal framing. The corrosion occurred in a variety of areas of the bottom, but quite a bit of it was near the framing.)
 The introduction of sacrificial or non-corroding wear surfaces at edges and other high wear points can reduce the amount of touch up which needs to be performed to protect the exterior surfaces.
 It is harder to get steel yacht with a ‘fine yacht finish’. For some people and some sailing preferences, simple utilitarian, ‘tool’ like finishes are appealing and make complete sense. But many people consider the visual aspects of a finely shaped and finely finished boat an important part of the sailing experience and for them, it becomes very expensive and labor intensive to achieve and maintain that level of finish.
(I personally do not see either approach as being inherently superior. Frankly, since the recession, Synergy is far closer in finish to a utilitarian chic’ than she is to a fine yacht. She has her fair share of ‘Franken-hardware’ in which old discarded hardware was brought back to life and/or adapted for a specific use for which it never was intended, of new hardware fabricated from scrap. Her decks sorely need to be painted. Her lack of pristine aesthetic maintenance does not alter the quality of the sailing experience for me, but does bother my wife. By the same token, I do admire a well kept boat.)
 It is much harder to achieve high performance capabilities in a steel hull, especially in a smaller boat. That said, as Brent rightly points out, for many, if not most, serious cruisers, ultimate speed is not an end all- be all and a properly designed steel boat can achieve relatively decent performance on a par with many heavy displacement cruising boats constructed in other materials.

Origami Construction:
 Since framing and additional reinforcement areas can be mostly eliminated it potentially reduces fabrication time, and corrosion problems.
 Done properly Origami Construction reduces the construction time for the hull by eliminating the fabrication time for framing, and reducing the length of cuts and welds. If the cut pattern is accurate and cut with precision, Origami Construction should produce a comparatively fair hull form requiring a minimum, if any, fairing.
 Origami Construction lends itself to a broader range of materials than steel. There is a lot of discussion of the plus and minuses of using aluminum for Origami Construction. The major plus is a reduction in hull weight. The negatives of aluminum are an incrementally greater material cost, the need for more specialized welding skills and equipment, the need to build in a controlled environment, trickier finishing choices, higher electrolysis risks, and less abrasion resistance. To a great extent stitch and glue plywood construction is a form of Origami Construction as well but I see that as off-topic.
 Structurally non-framed steel construction is a mixed bag. It can be argued that adding frames can increase the likelihood that the plating will sheer on impact should the impact occur on the skin near a frame. In the absence of a frame, the skin is more likely to absorb the impact by deflecting out of shape and in the case of a minor impact be able to be pressured back into shape. The flip side of that is that framing is very effective in distributing loads to a much larger area. Where frameless construction can be more resistant to very concentrated point loads like hitting a corner of a shipping container, framed construction is more effective in distributing large area impact such as might be the case a vessel dropping on its side on reef in big waves or getting pressed up against a dock.
 There is a surprising range of hull forms that can be achieved using Origami construction from the loosely 1970’s era cruising hull forms on Brent’s boats, to more modern higher performance shapes.
 Using Origami Construction is hard to create a hull form that does not have chines on some portion of the hull. To one degree or another, chines add drag, the amount of which is dependent on the shape, placement on the hull, and the angle of heel of the boat. It can be argued that this drag is of minimal significance in a heavy displacement for their length cruising hull forms whose owners are usually people who are not concerned with achieving high levels of performance. There are high performance hull forms which have chines, but these depend on comparatively light displacements for their lengths which is hard to achieve in small steel, distance-cruising boats.

Owner Builder-Amateur builder- Custom Builder
 While not strictly a steel construction issue, a lot of the discussion has focused on Owner, amateur, and custom boat builders. In that regard, steel readily lends itself to one off construction and to amateur boat builders. So do a lot of other materials, but not all materials are equally suited to one off construction.
 While many, if not most people can learn to weld and cut steel, like any manual skill, some people are likely to have an aptitude for metal fabrication, while others can eventually be taught, and still others will never be able to safely build a steel boat. This is not a knock on steel construction per se, because there are people who have no manual skills and lack the aptitude to learn these skills.
(In my case for example, I first learned to weld by attending a night course at a community college. I took the course with a friend of mine. From the first class on, no matter what type of weld we were learning that night my friend was able to lay down a good weld. It was much more of a struggle for me. With practice my welds became better, but they never were as clean and crisp as my friends. Its not that I never learned to weld at all. I built motorcycle frames using light gauge steel and chrome-molly tubing, and have made a variety of odds and ends, but I have a tough time thinking that I would ever get proficient enough to build a steel boat. By the same token, I am a pretty skilled woodworker and I have worked in boat yards doing glass work, and so if I wanted to build another boat I would probably be more comfortable working in wood or glass composites. I do not mean to suggest that either steel or wood, or glass are better materials for amateur boat building. My point here is that we all have our own skill sets and aptitudes and these are likely to shape a decision regarding ‘the right material’ for any particular person to chose if they were to build a boat.)
 The comparatively stiff nature of steel means that a minimum of temporary frames or supporting jigs are required. This saves material and fabrication time. This also means that almost any part that is fabricated, will remain as a part of the boat. That is a very efficient way to build a boat. By the same token, this is not unique to steel construction. This is also generally true of other panelized ways of constructing a boat.
 The panelized nature of steel construction allows a comparatively simply layout of the individual hull skin panels, and that saves lofting and fabrication time. In the case of a computer drafted design, it is possible to have very precise, full size, computer generated cutting patterns. These also save time, and helps assure a more precise rendition of the intended design. While Brent advocates purchasing full length plate as a time saver, in the situation where this is not available or practical, the use of computer generated patterns, allows efficient ‘nesting patterns’ to be developed in order to minimize waste.
 Computer aided design also permits designers to produce full scale cutting patterns for interior components and again that saves time and material. This is actually more useful for other boat building materials than with steel.
 Brent advocates a method for constructing steel boat interiors, which greatly reduces the need for precision cutting and fitting. Basically, steel tabs are welded to the hull wherever a wood bulkhead or flat comes up against the hull. Because these are comparatively short and discontinuous, it is easier to place then precisely and to avoid distortion of the skin. The bulkheads and flats are then screw fastened into place. There is a lot to be said for this approach. It allows for an interior which can be readily disassembled to provide access to the skin, or other components of the boat. With modern self-drilling, self-tapping fastenings this should be a comparatively fast and easy way to achieve a serviceable interior. This works uniquely well on a steel boat because steel boats do not rely as heavily on their interior components for their strength and because it is comparatively easy to weld a structurally robust tab almost anywhere it would be desired.
(There are similar techniques employed in ‘stitch and glue’ construction, but it is harder to get a fair hull if too many liberties are taken with the major interior components, and it is less prudent to screw fasten the bulkheads and flats into place, since they conventionally serve as a part of the boat’s structural.

Cons:
 Pound for pound, steel is one of the least efficient materials when viewed from a strength to weight standpoint. And in and of itself, adding hull and deck weight does nothing good for a boat.
(I make this statement predicated solely from the standpoint of traditional yacht engineering principles, but I also know that there are people who will find this counterintuitive and others who will disagree with this entirely. I tend to believe in tried and true structural science, but I also know that there are folks, who are skeptical about science in any form. If you are one of those, there will be no practical manner to have a meaningful discussion on this.

I also know that there are a lot of reasons that this may seem counterintuitive. For example if you pick up a piece of structural steel, it looks and feels nearly indestructible. Pick up a similar thickness piece of wood or fiberglass, there is not that same tactile sense of pure strength.

But steel is a very dense material. If we had equal volume blocks of steel, fiberglass, and a fir/cedar/ fiberglass composite, the steel would weigh four times as much as the fiberglass and approximately 17 times the weight of the wood/fiberglass composite. So if were comparing equal weight hull samples, a 5/16” thick steel plate would weigh as much as 1.25” thick fiberglass, and nearly 5 ½” thick wood/fiberglass composite. And if you believe the structural science, comparing panels of the same weight fiberglass will have over 4 ½ times the bending strength and over 6 ½ times the stiffness of the same weight steel hull. The wood/fiberglass composite will have over 11 times the bending strength and over 200 times the stiffness of the same weight steel hull.

But of course, normally people do not build wooden or fiberglass hulls this thick on the size boat that might be plated with 5/16” steel. Which comes to the another reason why this seems counterintuitive. There is a tendency to compare production fiberglass boats to one off or limited production steel boats. For the most part, the vast majority of production boats are designed to be affordable coastal cruisers and with that as their mission they care comparatively lightly constructed.

Often in these discussions we visualize a purpose constructed steel distance cruiser and compare it in our minds to some production coastal cruiser, and so it is easy to visualize steel as stronger. But if the mental comparison was between a composite hull of an equal weight to the steel, and think about the relative thicknesses of these materials, the intuitive strength advantage of steel would seem less obvious.

And I must admit that this is not all that cut and dry. While there may be strength differences between the various steel types, and the strength of a steel boat may be compromised by bad welding, the general strength of a steel boat, is less variable than the potential mix of structural capabilities, which can be found in glass composite or wooden construction.

Think for a moment of the strength differences between chopped glass set in a highly catalyzed polyester resin vs. a vacuum bagged Kevlar set in carefully calibrated vinylester resin. Or more dramatically, visualize a juniper edge-nailed, frameless, hull versus a cold molded cedar/fir laminate hull sheathed with Kevlar outer skins.

So to be fair and accurate it is probably more appropriate to say, that pound for pound glass composite or wooden construction can be stronger than steel. But to do so requires the proper choices of glass or wood composite construction and frankly more sophisticated engineering. If one of the goals is to minimize design costs, then Brent is right that up to a point, steel Origami Construction can reduce design time and still result in large safety margins.)

 Speed of getting out there:
There has been a lot of conversation suggesting that building an origami hull might be the fastest way to build a hull and deck. It may be, although ignoring the properties of the materials, I would suggest that stitch and glue plywood may be an equally quick way to build hull and deck.

But the hull and deck represents a pretty small portion of the labor (time) and material costs to build a boat. My recollection is that a hull and deck is roughly 20-25% of the overall cost of the finished boat. In fairness, that percentage will vary from material to material, boat design to boat design, level of fit and finish, and derives from a time that long ago when my Mom was having boats built in Asia and importing them to the States, and so should not be seen as gospel. But the point remains that even saving a 1/3 or more on the hull and deck is a pretty small savings overall, and that for any given owner-builder, the level of fit-out, fit and finish would be pretty much the same no matter what the boat is built of.

And if the goal is to build your own and get out there quickly, the fastest and cheapest answer may be to buy a really tired, f.g. boat, with a suitable cruising design (i.e. not some coastal cruiser, or cruiser racer) gut it and build it back using the same level of fit and finish that you planned to use on the steel boat, but save the time building and coating the hull. Of course, that only works if you do not have your mind set on owning a steel boat.

 Noise:
I have always been amazed at how noisy steel boats are. As Brent points out, you can use sprayed in foam, which is great stuff in terms of sound-deading and thermal insulation. But it’s just another step and another cost. And while the foam can be removed, it does make it harder to access the hull should you need to. Also many if not most foams will support fire. So will wood and fiberglass, but it somewhat reduces the theoretical non-combustible advantage of steel.

 Electrolysis:
In my life I have seen a steel hull come out of the water with the bottom peppered with small pin holes due to stray current and bad wiring. I have heard numerous stories of serious electrolysis problems on steel boats when I worked in boat yards. Electrolysis can happen to any boat with metal parts in the water, but it becomes a critical concern with a steel hull, especially in high salinity, warm water, or crowded harbors.

 Resale:
Whatever else you can say about steel, at least in the States there is a prejudice against steel as a boat building material. And that suppresses the resale value and number of willing buyers of a steel boat perhaps more than it should, at least relative to more widely accepted materials like fiberglass.

 Corrosion:
All boat building materials deteriorate eventually. Brent makes a case that properly built and properly maintained, steel boats should require a minimum of low skilled maintenance. It could be argued that it’s not much more labor intensive to paint an entire steel hull than it is to wax the topsides of a fiberglass boat. I actually buy that argument. But unlike fiberglass, if you do not recoat bare steel, corrosion will start and spread quickly. Whether it ever reaches a level of corrosion that undermines the structural capabilities of the boat depends on the nature of the design, build and maintenance.

Assuming for the moment that corrosion may not be a problem on the specific boats that Brent built, but in the context of a general discussion of the pros and cons of steel boats, the issue corrosion is a serious one, one that would discourage many potential boat buyers. It ultimately was one of the deal killers when I considered a steel hull.
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  #1403  
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Re: Pros and cons of steel sailboats

You ought to submit that to a cruising mag Jeff. That's quality stuff.
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Re: Pros and cons of steel sailboats

As a reader who came to this discussion late that was a very helpful summary Jeff, thank you!!
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Re: Pros and cons of steel sailboats

Man I wish I had your typing skills and patience Jeff.

Should we start a new thread for the alu skiff?
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Re: Pros and cons of steel sailboats

Quote:
Originally Posted by smackdaddy View Post
You ought to submit that to a cruising mag Jeff. That's quality stuff.
Thank you. Years ago I had written a series of 'technology of sailing' articles for Cruising World but it was just when the magazine was sold, so the series was never published.
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Re: Pros and cons of steel sailboats

Quote:
Originally Posted by Jeff_H View Post
While there has been a lot of interesting give and take in this tread, I must admit that it concernrs me a little that this thread has gone so far off the rails. This seems like a very worthwhile topic which could be a simple and linear dialogue on a moderately complex set of discussion points.

Instead, it has become the proverbial equivalent of the Tar Baby, clinging to whatever relevant or irrelevant issue it touches and dragging that issue along for often many semi-vitriolic pages at a time.

If SailNet was not the online equivalent of a waterside bar, it seems like it all should have been a lot simpler than this. And while it can be seen as inevitable that life style and economics figure into almost any conversation exploring alternative ways of going cruising, this thread has picked up more than its fair share of effluvia.

I do think that within the off-topic aspects of this discussion there are useful insights into how various sailors view the sport, and more specifically cruising. I think that it is useful to see these contrasting views of sailing and cruising and understand the seemingly broad range of viewpoints from distance cruising is the sole appropriate end unto itself, to views of sailing and cruising as a merely an adjunct part of a life well lived.

Within this thread there are similar debates about performance, survivability and aesthetics, with individuals claiming theirs is the one universally right position. (At least from my point of view, there is no such thing as one universally right way to enjoy sailing and cruising and that each individual gets to define their goals, tastes, fears, pleasures, priorities, budgets, and so on. And the only wrong answer is when that individual makes a decision that is at odds with their own defined preferences. But that’s another topic for the next thread.)

But that aside, I thought it would be useful to gather the points which address the basic subject of the Pros and Cons of steel construction as well as some of the related subjects. And drawing on the old political saw that every one gets to have their own opinion but no gets to have make up their own facts, I also think that there are a lot of ‘facts’ within this thread and a bunch of opinion being presented as fact.

If you weigh through the ebb and flow of these 1,400 or so posts, there are actually quite a few really good points about the pros and cons of steel construction. And while not everyone will agree on all of these points, I thought it might be useful to try to summarize the main ones (at least the ones that I agree with anyway). I also apologize that this is absurdly long and that I cut and pasted much of this from earlier discussions.

Pros:
Steel Construction in general:
 Steel offers a lot of strength in a very small volumetric area. This allows a comparatively low volume for skin and framing, and so more useable living space and storage space within the shell.
 Steel offers a tremendous amount of abrasion resistance.
 The materials for a steel hull can be purchased relatively inexpensively.
 (Assuming that the boat builder can deal with inclement weather) A steel hull can be constructed out in the weather saving the costs of leasing a large space to building.
 If a ‘work boat’ style finish is acceptable then finishes can be relatively inexpensive and should be fully within the range of skills of an amateur.
 Steel construction permits the fabrication of robust integral fittings which in turn minimizes the opportunity for hull and deck leaks. This is especially true if a steel deck is used since the welded hull to deck joint results in an effectively monolithic connection.
 An amateur with good welding skills and access to a decent quality welding and steel handling equipment can fabricate his own boat.
 Repairs to steel hulls can almost always be made in a manner that restores complete structural integrity.
 Steel boats are nearly infinitely re-buildable.
 Steel does not have an inherent structural load path orientation and so can disburse and absorb loading equally well in all directions. This is especially useful in impact loads which tend to occur in random directions relative to the normal service load paths.
 Steel has an inherent ductility which allows it to deform rather than puncture in an impact.
 Small steel vessels (perhaps under 40 or so feet) can be constructed essentially monocoque, with a minimum of framing, doublers and/or other forms of reinforcing. This is a bit of a trade off since omitting framing requires addition skin thickness and potentially results in greater overall weight. As boats get larger, the concentrated loadings from the keel, rudder, and sail plan loads become exponentially larger relative to the skin loadings, and so at some point knees, bulkheads, and stringers become critical to distributing these loads into the skin.
 The ability to weld together various boat components, and steel’s ability to deal with a pretty wide range of temperatures offer construction options such as pouring lead ballast right in the keel cavity, or having integral engine cooling water heat exchangers that are integral with the keel or hull.

Neither Pro or Con;
 Steel durability requires proper protection of the steel from corrosion. This is especially important on the interior of the boat and in high wear areas. Brent outlines his methods for prepping and painting the interior of the steel and describes a very long life span for that approach. But Brent also notes that almost no steel builders besides him do it his way and so based on Brent’s experience, corrosion problems in steel boats from other builders are much more likely to be problematic.
(My experience with older steel boats is that they have a comparatively short life. When I worked for Charlie Wittholz, I worked on drawings for a steel power boat. Charlie’s standard spec’s called for the interior of the boat to be sandblasted ‘white’, coated with a zinc rich epoxy, and then coated with several coats of coal tar epoxy. The interior of boats to within a foot vertically of the bottom of the turn of the bilge were then sprayed with closed cell foam. 20 years later that boat showed up in Annapolis. By then, the owners had replaced much of the bottom plating since it had rusted to a point where it had failed survey and there were still areas that were rusted (from memory) to less than approximately 1/8” of material remaining. There were several differences between the construction of this boat and the Origami boats in this boat was hard-chined and had transverse and longitudinal framing. The corrosion occurred in a variety of areas of the bottom, but quite a bit of it was near the framing.)
 The introduction of sacrificial or non-corroding wear surfaces at edges and other high wear points can reduce the amount of touch up which needs to be performed to protect the exterior surfaces.
 It is harder to get steel yacht with a ‘fine yacht finish’. For some people and some sailing preferences, simple utilitarian, ‘tool’ like finishes are appealing and make complete sense. But many people consider the visual aspects of a finely shaped and finely finished boat an important part of the sailing experience and for them, it becomes very expensive and labor intensive to achieve and maintain that level of finish.
(I personally do not see either approach as being inherently superior. Frankly, since the recession, Synergy is far closer in finish to a utilitarian chic’ than she is to a fine yacht. She has her fair share of ‘Franken-hardware’ in which old discarded hardware was brought back to life and/or adapted for a specific use for which it never was intended, of new hardware fabricated from scrap. Her decks sorely need to be painted. Her lack of pristine aesthetic maintenance does not alter the quality of the sailing experience for me, but does bother my wife. By the same token, I do admire a well kept boat.)
 It is much harder to achieve high performance capabilities in a steel hull, especially in a smaller boat. That said, as Brent rightly points out, for many, if not most, serious cruisers, ultimate speed is not an end all- be all and a properly designed steel boat can achieve relatively decent performance on a par with many heavy displacement cruising boats constructed in other materials.

Origami Construction:
 Since framing and additional reinforcement areas can be mostly eliminated it potentially reduces fabrication time, and corrosion problems.
 Done properly Origami Construction reduces the construction time for the hull by eliminating the fabrication time for framing, and reducing the length of cuts and welds. If the cut pattern is accurate and cut with precision, Origami Construction should produce a comparatively fair hull form requiring a minimum, if any, fairing.
 Origami Construction lends itself to a broader range of materials than steel. There is a lot of discussion of the plus and minuses of using aluminum for Origami Construction. The major plus is a reduction in hull weight. The negatives of aluminum are an incrementally greater material cost, the need for more specialized welding skills and equipment, the need to build in a controlled environment, trickier finishing choices, higher electrolysis risks, and less abrasion resistance. To a great extent stitch and glue plywood construction is a form of Origami Construction as well but I see that as off-topic.
 Structurally non-framed steel construction is a mixed bag. It can be argued that adding frames can increase the likelihood that the plating will sheer on impact should the impact occur on the skin near a frame. In the absence of a frame, the skin is more likely to absorb the impact by deflecting out of shape and in the case of a minor impact be able to be pressured back into shape. The flip side of that is that framing is very effective in distributing loads to a much larger area. Where frameless construction can be more resistant to very concentrated point loads like hitting a corner of a shipping container, framed construction is more effective in distributing large area impact such as might be the case a vessel dropping on its side on reef in big waves or getting pressed up against a dock.
 There is a surprising range of hull forms that can be achieved using Origami construction from the loosely 1970’s era cruising hull forms on Brent’s boats, to more modern higher performance shapes.
 Using Origami Construction is hard to create a hull form that does not have chines on some portion of the hull. To one degree or another, chines add drag, the amount of which is dependent on the shape, placement on the hull, and the angle of heel of the boat. It can be argued that this drag is of minimal significance in a heavy displacement for their length cruising hull forms whose owners are usually people who are not concerned with achieving high levels of performance. There are high performance hull forms which have chines, but these depend on comparatively light displacements for their lengths which is hard to achieve in small steel, distance-cruising boats.

Owner Builder-Amateur builder- Custom Builder
 While not strictly a steel construction issue, a lot of the discussion has focused on Owner, amateur, and custom boat builders. In that regard, steel readily lends itself to one off construction and to amateur boat builders. So do a lot of other materials, but not all materials are equally suited to one off construction.
 While many, if not most people can learn to weld and cut steel, like any manual skill, some people are likely to have an aptitude for metal fabrication, while others can eventually be taught, and still others will never be able to safely build a steel boat. This is not a knock on steel construction per se, because there are people who have no manual skills and lack the aptitude to learn these skills.
(In my case for example, I first learned to weld by attending a night course at a community college. I took the course with a friend of mine. From the first class on, no matter what type of weld we were learning that night my friend was able to lay down a good weld. It was much more of a struggle for me. With practice my welds became better, but they never were as clean and crisp as my friends. Its not that I never learned to weld at all. I built motorcycle frames using light gauge steel and chrome-molly tubing, and have made a variety of odds and ends, but I have a tough time thinking that I would ever get proficient enough to build a steel boat. By the same token, I am a pretty skilled woodworker and I have worked in boat yards doing glass work, and so if I wanted to build another boat I would probably be more comfortable working in wood or glass composites. I do not mean to suggest that either steel or wood, or glass are better materials for amateur boat building. My point here is that we all have our own skill sets and aptitudes and these are likely to shape a decision regarding ‘the right material’ for any particular person to chose if they were to build a boat.)
 The comparatively stiff nature of steel means that a minimum of temporary frames or supporting jigs are required. This saves material and fabrication time. This also means that almost any part that is fabricated, will remain as a part of the boat. That is a very efficient way to build a boat. By the same token, this is not unique to steel construction. This is also generally true of other panelized ways of constructing a boat.
 The panelized nature of steel construction allows a comparatively simply layout of the individual hull skin panels, and that saves lofting and fabrication time. In the case of a computer drafted design, it is possible to have very precise, full size, computer generated cutting patterns. These also save time, and helps assure a more precise rendition of the intended design. While Brent advocates purchasing full length plate as a time saver, in the situation where this is not available or practical, the use of computer generated patterns, allows efficient ‘nesting patterns’ to be developed in order to minimize waste.
 Computer aided design also permits designers to produce full scale cutting patterns for interior components and again that saves time and material. This is actually more useful for other boat building materials than with steel.
 Brent advocates a method for constructing steel boat interiors, which greatly reduces the need for precision cutting and fitting. Basically, steel tabs are welded to the hull wherever a wood bulkhead or flat comes up against the hull. Because these are comparatively short and discontinuous, it is easier to place then precisely and to avoid distortion of the skin. The bulkheads and flats are then screw fastened into place. There is a lot to be said for this approach. It allows for an interior which can be readily disassembled to provide access to the skin, or other components of the boat. With modern self-drilling, self-tapping fastenings this should be a comparatively fast and easy way to achieve a serviceable interior. This works uniquely well on a steel boat because steel boats do not rely as heavily on their interior components for their strength and because it is comparatively easy to weld a structurally robust tab almost anywhere it would be desired.
(There are similar techniques employed in ‘stitch and glue’ construction, but it is harder to get a fair hull if too many liberties are taken with the major interior components, and it is less prudent to screw fasten the bulkheads and flats into place, since they conventionally serve as a part of the boat’s structural.

Cons:
 Pound for pound, steel is one of the least efficient materials when viewed from a strength to weight standpoint. And in and of itself, adding hull and deck weight does nothing good for a boat.
(I make this statement predicated solely from the standpoint of traditional yacht engineering principles, but I also know that there are people who will find this counterintuitive and others who will disagree with this entirely. I tend to believe in tried and true structural science, but I also know that there are folks, who are skeptical about science in any form. If you are one of those, there will be no practical manner to have a meaningful discussion on this.

I also know that there are a lot of reasons that this may seem counterintuitive. For example if you pick up a piece of structural steel, it looks and feels nearly indestructible. Pick up a similar thickness piece of wood or fiberglass, there is not that same tactile sense of pure strength.

But steel is a very dense material. If we had equal volume blocks of steel, fiberglass, and a fir/cedar/ fiberglass composite, the steel would weigh four times as much as the fiberglass and approximately 17 times the weight of the wood/fiberglass composite. So if were comparing equal weight hull samples, a 5/16” thick steel plate would weigh as much as 1.25” thick fiberglass, and nearly 5 ½” thick wood/fiberglass composite. And if you believe the structural science, comparing panels of the same weight fiberglass will have over 4 ½ times the bending strength and over 6 ½ times the stiffness of the same weight steel hull. The wood/fiberglass composite will have over 11 times the bending strength and over 200 times the stiffness of the same weight steel hull.

But of course, normally people do not build wooden or fiberglass hulls this thick on the size boat that might be plated with 5/16” steel. Which comes to the another reason why this seems counterintuitive. There is a tendency to compare production fiberglass boats to one off or limited production steel boats. For the most part, the vast majority of production boats are designed to be affordable coastal cruisers and with that as their mission they care comparatively lightly constructed.

Often in these discussions we visualize a purpose constructed steel distance cruiser and compare it in our minds to some production coastal cruiser, and so it is easy to visualize steel as stronger. But if the mental comparison was between a composite hull of an equal weight to the steel, and think about the relative thicknesses of these materials, the intuitive strength advantage of steel would seem less obvious.

And I must admit that this is not all that cut and dry. While there may be strength differences between the various steel types, and the strength of a steel boat may be compromised by bad welding, the general strength of a steel boat, is less variable than the potential mix of structural capabilities, which can be found in glass composite or wooden construction.

Think for a moment of the strength differences between chopped glass set in a highly catalyzed polyester resin vs. a vacuum bagged Kevlar set in carefully calibrated vinylester resin. Or more dramatically, visualize a juniper edge-nailed, frameless, hull versus a cold molded cedar/fir laminate hull sheathed with Kevlar outer skins.

So to be fair and accurate it is probably more appropriate to say, that pound for pound glass composite or wooden construction can be stronger than steel. But to do so requires the proper choices of glass or wood composite construction and frankly more sophisticated engineering. If one of the goals is to minimize design costs, then Brent is right that up to a point, steel Origami Construction can reduce design time and still result in large safety margins.)

 Speed of getting out there:
There has been a lot of conversation suggesting that building an origami hull might be the fastest way to build a hull and deck. It may be, although ignoring the properties of the materials, I would suggest that stitch and glue plywood may be an equally quick way to build hull and deck.

But the hull and deck represents a pretty small portion of the labor (time) and material costs to build a boat. My recollection is that a hull and deck is roughly 20-25% of the overall cost of the finished boat. In fairness, that percentage will vary from material to material, boat design to boat design, level of fit and finish, and derives from a time that long ago when my Mom was having boats built in Asia and importing them to the States, and so should not be seen as gospel. But the point remains that even saving a 1/3 or more on the hull and deck is a pretty small savings overall, and that for any given owner-builder, the level of fit-out, fit and finish would be pretty much the same no matter what the boat is built of.

And if the goal is to build your own and get out there quickly, the fastest and cheapest answer may be to buy a really tired, f.g. boat, with a suitable cruising design (i.e. not some coastal cruiser, or cruiser racer) gut it and build it back using the same level of fit and finish that you planned to use on the steel boat, but save the time building and coating the hull. Of course, that only works if you do not have your mind set on owning a steel boat.

 Noise:
I have always been amazed at how noisy steel boats are. As Brent points out, you can use sprayed in foam, which is great stuff in terms of sound-deading and thermal insulation. But it’s just another step and another cost. And while the foam can be removed, it does make it harder to access the hull should you need to. Also many if not most foams will support fire. So will wood and fiberglass, but it somewhat reduces the theoretical non-combustible advantage of steel.

 Electrolysis:
In my life I have seen a steel hull come out of the water with the bottom peppered with small pin holes due to stray current and bad wiring. I have heard numerous stories of serious electrolysis problems on steel boats when I worked in boat yards. Electrolysis can happen to any boat with metal parts in the water, but it becomes a critical concern with a steel hull, especially in high salinity, warm water, or crowded harbors.

 Resale:
Whatever else you can say about steel, at least in the States there is a prejudice against steel as a boat building material. And that suppresses the resale value and number of willing buyers of a steel boat perhaps more than it should, at least relative to more widely accepted materials like fiberglass.

 Corrosion:
All boat building materials deteriorate eventually. Brent makes a case that properly built and properly maintained, steel boats should require a minimum of low skilled maintenance. It could be argued that it’s not much more labor intensive to paint an entire steel hull than it is to wax the topsides of a fiberglass boat. I actually buy that argument. But unlike fiberglass, if you do not recoat bare steel, corrosion will start and spread quickly. Whether it ever reaches a level of corrosion that undermines the structural capabilities of the boat depends on the nature of the design, build and maintenance.

Assuming for the moment that corrosion may not be a problem on the specific boats that Brent built, but in the context of a general discussion of the pros and cons of steel boats, the issue corrosion is a serious one, one that would discourage many potential boat buyers. It ultimately was one of the deal killers when I considered a steel hull.
Excellent summation! While I disagree with some of the cons, which I will deal with later, you have summed up more than 98 % of it very well, and have largely answered the initial question.
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Re: Pros and cons of steel sailboats

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Originally Posted by copacabana View Post
I'm sure Brent will chime in shortly with some good advice. His book has the plans for an origami aluminium dinghy that can perhaps be tinkered with to get Bob's shapes. I'd love to see this go forward- the world needs a decent aluminium nesting dinghy!
You can experiment with a cereal box and scissors to get an idea of what shapes you can get with origami. Designing an origami dinghy should go back and forth from drawings and calculations to a model, and back again.
Many friends have made aluminium dinghies, and cut them in half for nesting dinghies. All have been extremely happy with the results.
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Re: Pros and cons of steel sailboats

Brent:
So you are saying I have to see what I can get with the model before pinning the drawing down? I kind of figured that. But I'm hoping with some 3D modelling we can short cut the process a bit.

I'd sure like you opinion on scantlings for a 15' skiff.
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Re: Pros and cons of steel sailboats

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Originally Posted by bobperry View Post
Desert's post got me thinking. I laid awake all night thinking.

An alu 15' by 3.5' double ended row boat in Brent's origami method. I'd need help from Brent as I don't know how much shape or even what shape I can get in the ends. I have end shapes in mind. I just don't know if they will wrk in the origami method.

I need e new boat for my rocky beach and this could be the boat. I need to sketch a bit and do a quick weight estimate. I'd figure 1/8" plate for durability. I was thinking a .25" thick centerline backbone plate.

I'm going to come up with a drawing in the next few days. I'll post it here and see if I can get Brent to comment on the details. If this is workable I'll make the plans available free. The key will be being able to control the shapes in the ends so I can get the numbers and look that I want.
It shouldn't be too hard. Origami is as simple as it looks. I'll be happy to give you all the help you need, but my internet access can be sporadic, and sometimes brief, as I cruise full time.
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