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Farr 11.6 (Farr 38)
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I am quite familiar with Brent's designs. Given your collective fears, Puncture resistance, Keeping a boat afloat with a puncture, Self-righting, Odds of being rolled, This is the wrong boat for you. Despite Brent's physics defying propaganda to the contrary, those of us who have actually designed boats and performed the engineering calculations find Brent's claims to defy the science and proper design practices. I will not get into detail on this here, but if you search SailNet there are very detailed discussions on these topics.

I will start with steel as a boat building material. While steel has enormous strength per square inch of material, and does offer excellent abrasion resistance, it is an extremely dense material as compared to any other boat building materials. As a result when viewed on a pound for pound basis. it is the weakest in impact resistance, bending and stiffness of all of typical boat building materials with the possible exception of Ferro cement.

I know that this seems counter-intuitive if you have not studied engineering, but because steel is so dense (lbs per cu. in), for the same weight other materials will be much thicker and that extra thickness more than makes up for differences in strength per square inch.

Over the years, a large number of naval architects, marine engineers, and yacht designers have tries to explain this to Brent, showing him the math, explaining the science, etc. Despite that Brent continued to come up with BS analogies that frankly reflect a lack of understanding of the basic science and engineering principles.

Its not that steel is a bad building material for larger boats (40-50 feet and above) , where the skin weight begins to be proportional to the displacement of the boat. But in boats under roughly 40 feet, the weight of the hull becomes disproportionately large. It is important to understand that in and of itself weight does nothing incoherently good for a boat. Weight does not equate to making a boat more seaworthy, or stable, or mean a more comfortable motion. Weight does not mean there is more strength, carrying capacity or ease of handling. It does not make the boat perform better. In fact as a broad generality, weight is mostly detrimental to everyone of those items.

When you talk about a 26 foot steel boat, the vertical height of the added weight of the steel hull, topsides and cabin structure above the center of buoyancy means that there is significantly less stability and a much greater chance of the boat being rolled and not coming up quickly. When you add the weight of the pilot house, the chances of being rolled increases further.

But also when a boat has a proportionately large amount of weight in its hull, deck, rig, and cabin structure, there tends to be some mix in reduced ballast weight, and reduced carrying capacity. The reduced ballast weight means a further reduction in stability so that the boat is more likely to roll excessively and be flipped in a steep sea.

Then there is the bilge keels. (Twin keels) By and large, bilge keels tend to have a lot of drag relative to lift. Higher drag means that the boat needs to carry more sail area for it's weight. More sail area means that the boat needs more stability. We are starting with a boat that has diminished stability due to its weight carried high and reduced ballast, but now bilge keel is added to the mix. Bilge keels generally require a lot more ballast to achieve the same stability as a single fin.

So cummulatively, stability and righting capacity are greatly diminished as compared to a boat constructed of conventional materials.

The point of this being that you would be way safer with a robustly constructed fiberglass boat. I you are concerned with grounding on coral, get one with external ballast so that you are touching bottom with metal rather than fiberglass.

Respectfully,
Jeff
 

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Farr 11.6 (Farr 38)
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10,213 Posts
That is the same type of grossly inaccurate claims that Brent liked to make. Over the years a large number of yacht designers, marine engineers, and people with engineering backgrounds have provided detailed calculations demonstrating that comments like that are fanciful and ignore the reality of the situation.

As I previously mentioned, there are detailed discussions all over the internet that completely debunks statements like those. If anyone is interested in understanding the reality of small steel boats and in particular Brent's small steel boats, I suggest that you Google those discussions to better understand the merits and liabilities of small steel boats and in particular Swain's designs.
Jeff
 
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