Miscellaneous


Marine distance measurements are expressed in terms of nautical miles. A nautical mile is significantly different from a common or statute mile. The conversion is 1 nautical mile = 1.151 statute miles, or approximately 6076 ft ( vs. 5280 ft for a statute mile. )

Why such a confounded thing as this? Here's why:


Side-scan sonar is a modern method of underwater imaging that can produce remarkably detailed and realistic views of shipwrecks and other bottom features using sound rather than light.

side-scan sonar shipwreck SS Delaware
Notice all the detail in this side-scan sonar image of the Delaware.

Another entry from the Way-back machine:

NJ Scuba
George Hoffman

"Gentleman George"

by Dan Berg

Note: George Hoffman passed away January 14, 1997, about a year after this article was written. His death is a great loss to the diving community and he will be missed by us all.


Artifacts recovered after long immersion in salt or freshwater require conservation treatment if they are to last. On exposure to high concentrations of oxygen in the air, iron artifacts will bloom into piles of rust. Wood will crack and split if dried out improperly. Organic materials will crumble to dust.

The manual below details conservation methods for many types of materials and artifacts.


wire drag
A fine diagram of a wire-drag operation. The wire is towed between two tugboats, suspended by buoys at a predisposed depth. When the cable snags on an obstruction and draws into a V, the buoys point to its location.

Wire dragging is an operation used to locate and/or reduce the navigational hazard of a sunken wreck, rock, or other obstruction.


Alpha-Numeric Signal Flags

In this modern age of radio, these signal flags are a quaint anachronism that is no longer used, although they were once very important in ship-to-shore and ship-to-ship communications. Each flag stands for both a letter value and a shorthand message. The letters are expressed here in the modern international phonetic alphabet, in which A-B-C would be spoken Alpha-Bravo-Charlie (see below).


Paintshop

One of the great advantages of digital photography is the ease with which the resulting photos can be manipulated and improved later using your computer and an image editing program. Of course, you can also do this by scanning film prints or slides, but dealing directly with digital images is faster, easier, and virtually free.

Underwater photos ( film or digital ) may suffer from the following problems:

  • lack of contrast
  • lack of sharpness
  • excessive darkness or light
  • loss of red tones / poor color balance
  • poor framing and composition