The Model Engineer and Practical Electrician Volume 6

The Model Engineer and Practical Electrician Volume 6

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1902 edition. Excerpt: ... and has nothing to do with the outline shape of the keel or fin. A boat would be just as stiff if the bulb were supended on two or three rigid wires. Such a boat would be more apt to roll in choppy water when the wind was too light to keep the sails full, because there would be no lateral plane to check such movement by doing the work of bilge keel on a steamer; but to stop jerky motion of this kind, two fins are just as good as one, if of the same area. Stiffness under sail, however, in a fresh breeze is a different thing altogether. If the pressure of the water on the fin were to make the boat stiffer, as is suggested, the pressure would have to be on the weather or upper surface when the boat is heeled; whereas the pressure is, of course, on the lee or under side, being the lateral resistance of the water, and its tendency is to heel the boat still more and not to bring her upright. A racing yacht must be designed so that she will turn very easily, and a deep short fin or centre-plate amidships, as in the 24-footer Speedwell or Sorceress, renders the boat very quick on her helm. Precisely the opposite is required of a model, which must stil in a straight line; every obstacle must be placed in the way of a turning movement. Plenty of lateral resistance should therefore be put near the ends of the water-line; the further from the centre the flat surfaces, the steadier the boat will sail. Now a single fin, reaching nearly to the ends of the waterline and deep enough to provide a good leverage to the bulb, will have a very large wetted surface, a good deal of which is doing no useful work, but is causing unnecessary surface friction and diminishing the speed very much. If, therefore, a large piece be removed from the centre of the fin, ..
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Product details

  • Paperback | 246 pages
  • 189 x 246 x 13mm | 445g
  • United States
  • English
  • black & white illustrations
  • 1236940067
  • 9781236940063