Wednesday, March 28, 2012

When is Reason Called Speculation? Responding to Rod Meldrum’s Answer – Part VII

Continuing from the last post regarding the Lord’s answer to these two questions. Though Meldrum did not even attempt to answer the WHY of these questions, the interesting thing is, the Lord actually tells us WHY he had Nephi build a ship unlike that of men of Nephi’s day. He made it quite clear when he told Nephi:

“And it came to pass that the Lord spake unto me, saying: Thou shalt construct a ship, after the manner which I shall show thee, that I may carry thy people across these waters” (1 Nephi 17:8 ).

ACROSS THESE WATERS. The ship the Lord designed for Nephi and in which the Lehi Colony sailed to the Land of Promise, was built to cross the vast oceans between Arabia and the Western Hemisphere. As has been pointed out numerous times, the pounding of waves and currents, and the drag of winds on sails, requires a very strong vessel to sail in deep water.

This is because a ship in deep water with heavy sail has a tendency to exceed a speed/length ratio of 0.94 and outrun most of its bow wave, and as the ship exceeds 1.34 hull speed (displacement speed) the wavelength becomes longer than the hull, and the stern is no longer supported by the wake, causing the stern to squat, and the bow rise. The hull then climbs its own bow wave, and resistance begins to increase at a very high rate. Wave making resistance begins to increase dramatically when the vessel reaches a speed-length ratio of slightly less than 1.20. This is due to a rapid increase of resistance due to the transverse wave train.

This very sharp rise in resistance at around a speed-length ratio of 1.3 to 1.5 probably seemed insurmountable in early sailing ships and so became an apparent barrier. On the other hand, these values change dramatically as the general proportions and shape of the hull are changed. Modern displacement designs that can easily exceed their 'hull speed' include hulls with very fine ends, long hulls with relatively narrow beam and wave-piercing designs, such as modern naval vessels. For wooden sailing ships of the European era, such problems typically did not exist since the width to length ratio precluded such speeds, typically at speed/length ratios of under 1.0. And obviously, no coastal vessel ever reached such hull speeds and thus never experienced such hull pounding as deep ocean vessels.

As an example, a 100-foot boat length at the water line translates to a maximum hull speed of 1.34 at 13.4 knots; an 80-foot length would be 11.99 knots to a maximum hull speed of 1.34; and a 120-foot length reaches maximum hull speed of 1.34 at 14.68 knots, while a 60 foot hull reaches maximum hull speed of 1.34 at 10.38 knots. Columbus’ ship, the “Santa Maria” (shown above), a merchant cargo vessel, was about 66 feet long at the water line, which means it reached its maximum hull speed of 1.34 doing 10.89 knots (the maximum knot speed for a Carrack was 8 knots), and Columbus probably averaged about 4 to 5 knots.

In addition, deep ocean ships then as now, are subject to the pounding of ocean surface waves and sea swell as well as effects of wind and weather. These movements can be stressful for passengers and equipment, and must be controlled if possible. The rolling movement can be controlled, to an extent, by ballasting or by devices such as fin stabilizers. Pitching movement is more difficult to limit and can be dangerous if the bow submerges in the waves, a phenomenon called pounding. Sometimes, ships must change course or speed to stop violent rolling or pitching. Unfortunately, ships “driven forth before the wind” are unable to do this with the exception of lowering the sail, which then makes rudder control almost impossible.

During the later age of sail, the timbers—wooden support frames of a sailing ship—could be pounded so hard in rough seas that the phrase “Shiver the timbers” came into use (later became the slang term “Shiver me timbers” used by pirates meant to convey a feeling of fear and awe—much like “Well blow me down” or “May God strike me dead”). In heavy seas, ships would be lifted up and pounded down so hard as to “shiver” the timbers, startling the sailors. This was also reminiscent of the splintering of timbers from such pounding.

Consequently, the extreme pounding of waves on the hull and the torque of wind on sails, required a very strong, heavy built ship for the Lehi Colony to sail the oceans to reach the Land of Promise, which was something that man in 600 B.C., and for many years afterward, did not know how to build. But the Lord did, and instructed Nephi to build his ship “not after the manner of men; but I did build it after the manner which the Lord had shown unto me; wherefore, it was not after the manner of men” (1 Nephi 18:2).

(See the next post, “When is Reason Called Speculation? Responding to Rod Meldrum’s Answer – Part VIII – Meldrum’s Phoenician Connection” to see how erroneous thinking leads to mistakes in judgment)

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