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Old 07-06-2013
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Re: 6 Americans, 1 Brit vanish at sea

Quote:
Originally Posted by MarkofSeaLife View Post
I read the article, which seemed to me to be very snotty, especially in light of the several souls now presumed lost and most likely perished. It also seemed that whoever wrote it had no idea that "several tons" of lead in the keel is what keeps the boat upright, and will also return the boat to an upright position in the event of a knockdown.

We have all seen video of powerboats with no weighted keel turned turtle, but sailboats will roll, and then especially if dismasted, right themselves more often than not. I cannot speak to the accusations against the Captain/Owner of Nina having been negligent in his maintenance, though others here do know him and may be able to give firsthand accounts of his maintenance habits. I can say that those who continually state that wooden ships and especially very well built wooden yachts are somehow inferior to vessels using metal in their hulls are both disingenuous and dishonest. A well designed vessel using quality wood will in fact often outlast a metal hulled vessel. Period. Metal actually does suffer from micro-fractures caused by repeated stress and in every single case metal will eventually suffer to the point which it will become brittle and crack. Wood has its drawbacks, but stress fractures in quality timbers are far less likely than one might imagine. The reason for this is that metal molecules align themselves in the process of manufacture and cyclic loading and cause cracks to occur, as seen in the photo here:




Note how the image shows the material is striated and layered, when metal does this it will literally pull apart and tear, that is what a crack is, it is a tear that begins at the molecular level as the material is repeatedly compressed under loads. This is what metal fatigue looks like under a scanning electron microscope, and you can see that it is not a good thing.


Wood is a very different material,wood is the product of the metabolic and physiological activity of woody plants. Because of its function in live plants, wood must be mechanically resistant (it sustains the weight of the crown, leaves, water, wind, snow etc.) and at the same time it must be porous: photosynthesis in the leaves requires water and inorganic substances (sap) to pass through the wood from the ground. Both these functions, mechanical support and sap conduction, are supplied by cells. Wood is composed of cells which are characterized by a solid wall surrounding a lumen. The wood cells are fusiform and about 90% of the cells in the wood have a vertical orientation. The cell wall has a good mechanical resistance to traction and compression, and the cell lumen can be covered by the sap. When dried in a kiln wood still retains most of its original characteristics, and in fact it is never truly dry it retains a 6% to 15% moisture content by weight even when dried, this prevents honeycombing and collapse of the cell walls.

Because wood is an organic polymer it is extremely resilient and will bear a great deal more cyclic loading without damage than steel. A polymer is a large molecule formed from many smaller identical units called monomers linked together at the molecular level. This linking acts like a chain to hold the cells together, and is what makes wood the most widely used material in the world. It is strong yet flexible, and it is one of the most perfect materials from which to construct a boat.

Wood is a fiber woven together at the molecular level, it remains flexible yet retains its hardness, will retain the form it is shaped into and not loose its strength when formed correctly. Steel is made up of interlocked crystal lattices, carbon is used to harden the steel and keep the lattices interlocked, preventing the lattices from sliding over one another. This hardening also makes it more brittle, so either low carbon steel and it is too soft, or high carbon steel and it becomes more brittle. This also means that every single method of forming steel once it has cooled and is tempered will also damage the molecular structure and cause the lattices to begin sliding.

Wood is certainly damaged in forming it, but just like a polymer rope, the frayed ends can be kept from unraveling by applying heat, through sanding or polishing. It must be sealed and treated properly to maintain the proper level of moisture in the cell walls, and it must be maintained to keep the moisture level where it needs to be.


Personally, I would not go to sea in a metal boat.
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