Check out the law of mechanical similitude for a comparison between large boats and small ones in terms of the relative strengths .The bigger the boat the more marginal the strength becomes. Small steel boats are grossly over strength, super tankers marginal. An example would be the test I suggested to Smack. Take a tin can, sealed ( a condensed milk can with the holes soldered shut would work) Stand waist deep in water and try making a hole in it with an aluminium baseball bat . Now imagine a similar sized bat to can ratio on a super tanker. You wont make a hole in the can, no matter how hard you try, but the super tanker hit with a much larger bat that itself, would break up quickly. A small steel sailboat can pound on a lee shore for weeks without serious damage , but a super tanker in dry dock will break in half if the supports are not perfect. Shipyard workers can confirm this.
That is how the law of mechanical similitude works.
I have zero condensation inside my hull, despite living aboard her full time for 29 years. Spray foam eliminates it completely. It is however very important o heavily epoxy the inside, before spray foaming. Foam does not protect it reliably. Many commercially made boats ( Foulkes Fehr, Amazon ) have zero epoxy under the y foam, and rust from the inside out , sometimes rather quickly. Anywhere I have dug out sprayfoam, in my heavily epoxied interior , to install thru hulls, deck conduits, etc., the steel under it has been in perfect condition.
Spray foam should be carried to the floor boards. Some fish boats were foamed right down into the bilges and the foam acted like wicks, drawing bilge water high up, causing serious corrosion. Hulls and keels made out of only 1/8th plate doen't help any. You need a place for the water to drain out of the foam. Leave the foam out a foot either side of the centreline, and in any engine compartment .
On deck, the biggest maintenance problems are paint chipping of outside corners, Flat surfaces are far less problematic. If you have corrosion problems on flat surfaces, the paint is not thick enough or the steel under it was not clean enough ,before painting. Trimming al outside corners On a steel boat with stainless, can reduce maintenance by 80%
For marina queens, and "occasional use" boats , fibreglass is far less maintenance, than a steel boat. For full time, hard use, where a plastic boat would have cleats worked loose, things breaking , and deck leaks to constantly re-seal , workboat priorities prevail , and a steel boat becomes far less maintenance.
Bob Perry, an indisputable expert on fibreglass, knows next to nothing about steel boats. Nor does Smack. Neither has any hands on experience building, , cruising in, or maintaining a steel boat over many decades .
Best get your steel boat info from those who have built or cruised in one successfully, over decades. Otherwise you are getting only misinformation spread by plastic boat salesmen.
To see what a small boat can take , check out the" Gringo "photos on cruisers forum. That kind of impact would have cut a much larger boat in half.
Brent, I work in the construction industry. The construction industry uses all different kinds of materials to get the job done. The one thing that is indisputable is that each material has it's strengths and weaknesses. There is no such thing as a material that works best in every single application. I've read enough of your posts to see that you are no different than a "plastic boat salesman". You tout the near mythical greatness of your own work while cramming your impressive experience with steel down everyone's throat and at the same time you feel the need to dismiss the opinions or material preferences of others. Are you an expert in "plastic boats"? You state in effect that the likes of Bob Perry, whom I would consider an expert in the "plastic" field, or Smackdaddy, an apparent leader in the art of research, have no right to comment about the con's of steel because they don't have your experience with it and yet you seem to have the right to continuously dismiss "plastic" when I seriously doubt that you can approach the experience level of Mr. Perry or have even a minute idea of the research Smack has put in on the subject.
I've read your posts in order to pick out the occasional gold nugget of experience, like your suggestion of trimming in stainless or the importance of thoroughly cleaning steel prior to applying epoxy but all the other negative rhetoric you include does not make me want to go out of my way to find them. You're an expert in steel. You're one of the supreme few that has designed, built, maintained, sailed, cruised, lived on, rammed a reef, and wrote a book about steel boats. I think we all get it by now. Good for you. I won't speak for anyone else but I know I'm sick of reading about it. It would be nice if you would self edit your posts to remove the attitude and the "steel boat salesman" crap prior to hitting "reply". I would be just as happy if you didn't respond to any of my posts at all.