Tide staff system

Details Tide staff system Tide staff system

2002-11-19

2004-10-12

Williams, Hezron (Department: 2856)

Measuring and testing

Liquid level or depth gauge

C073S29000R, C073S170060, C073S170050, C073S306000, C073S309000, C073S311000

Reexamination Certificate

active

06802219

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a segmented cylindrical tide-staff system capable of being erected easily at remote areas for dynamic calibration of electronic tide meters and computer models of tides.
BACKGROUND OF THE INVENTION
The traditional method of coastal hydrographic surveying relies on a tide gauge, which is a device for measurement of tide levels. The tidal height at any place varies with time. The tide gauge records water heights with reference to a recognized datum level known as chart datum (CD), which is a safe low water level in order to maintain the minimum depth useful for transporting a vessel safely to port. The tide gauge records water heights at a selected specified time interval, usually 30 minutes. However, in regions where the tidal height changes rapidly, water heights need to be recorded at much closer time-intervals, say 5 minutes. Traditionally, in the ports all over the world, a human observer records readings from a tide-staff at selected specified time-intervals as described by David. T. Pugh [“
Tides, Surges and Mean Sea
-
Level: A Handbook for Engineers and Scientists
”, David. T. Pugh, John Wiley and Sons, New York, pp. 1-472 (1987)]. The data recorded is primarily used for operational applications such as hydrographic survey and navigation. The tide-staff readings are also used for periodic chart-datum adjustment of graphical records obtained from float-driven tide gauges as described by H. R. Palmer [“Description of Graphical Register of Tides and Winds”, H. R. Palmer,
Philos. Trans. Roy. Soc. London
, 121, 209-213 (1831)]. In hydrographic survey, the time-indexed tide is subtracted from time-indexed soundings to provide data for preparation of bathymetric maps, or nautical charts. With advances in nautical charting the application of tide-staff is going to become increasingly important for dynamic calibration of electronic tide gauges and computer models of tides as described by Antony Joseph [In: “Progress in the Technology of Nautical Charting”,
Encyclopedia of Microcomputers, Antony Joseph, Marcel Dekker, Inc
, New York, Vol. 28, pp. 271-310 (2002)].
Hitherto known systems for tide measurement are shown in
FIGS. 1 and 2
.
FIG. 1
represents a typical design example, showing a conventional tide-staff of the prior art used for tide level measurement with reference to the chart datum (CD), which consists primarily of a single graduated staff [
1
], which is usually made of wood or any similar material and either driven into the seabed [
2
] or erected vertically on the side of a jetty-wall. The tide staff reading [
3
] is in a form visually readable to an average person, and provides precise visual information from a close distance regarding the instantaneous tide level [
4
] at a given coastal site.
FIG. 2
represents another conventional system of the prior art used for tide level measurement with reference to chart datum (CD), which consists primarily of a single staff [
5
], which is usually made of iron or a conventional rail pole which is either driven into the seabed [
6
] or erected vertically on the side of a jetty-wall. Metallic strips [
7
] are welded to the iron staff [
5
]. Usually each strip has a total length of 20 cm and is sub-divided into two parts [
8
] and [
9
] of length 10 cm each differing in shape to distinguish between these two parts. The adjacent strips of the tide-staff are painted in differing colors to reduce the tide-observer's burden during tide-staff reading.
Hitherto known systems for tide measurement, describe a tide level recorder that records tide elevations utilizing a vertical free-floating graduated rod-staff, and time-tagging the tide level readings with the use of a chronometer [Jack E. Guth, “Photo-Tide Level Recorder”, U.S. Pat. No. 4,268,839 dated May 19, 1981]. The tide level recorder comprises a vertically oriented graduated rod-staff, which is located on a plastic float to provide it sufficient buoyancy. The rod-staff, which is popularly known as tide-staff, is floated within the confines of a 6-inch diameter plastic vertical cylindrical tube, which functions as a tide-well. A T-shaped junction box attached to the tide-well near its upper end at a point above the highest expected tide level houses a chronometer, an index mark, a time-lapse camera, and a light flash synchronized with the camera. A plastic tube that is mounted vertically above the T-shaped junction box functions as a vertical guide for the rod-staff as it rises and falls with the tide. The tide-well has an orifice near its bottom end to allow the free flow of water in and out as the tide rises and falls. The length and diameter of the tide-well, rod-staff, and rod-staff guide tube, and the height of the index mark and the camera above the orifice are variable and depend on the tidal range, i.e., the extend of vertical swing in water level at the place. The orifice dampens external wave action. The elevation of the rod-staff is relative to the fixed index mark. This index mark is located at a fixed height above the orifice, and its level with reference to a local benchmark can be ascertained from conventional survey techniques. The index mark enables reading the rod-staff graduations as the staff rises and falls with the tide. An automatic time-lapse camera located opposite the index mark enables recording the rod-staff graduation readings and simultaneous time-readings from a chronometer, which is located near the index mark. This arrangement enables relating the tide elevation record to specific times of the day, during which the rod-staff readings are made. An advantage of this device is that it eliminates mechanical errors evident in float-driven gauges operating with the support of counter weights and springs as described by Antony Joseph [“Modern Techniques of Sea Level Measurement”,
Encyclopedia of Microcomputers, Antony Joseph, Marcel Dekker, Inc., New York
, Vol. 23, pp. 319-344, (1999)]. Another advantage of this system is that by photo-recording the staff elevation from a fixed camera platform, relative to a fixed reference level, it eliminates the need for the presence of a human tide-staff reader for direct reading of the tide level on the staff. However, a major disadvantage of this device is that it requires a purpose-built structure for erection of the tide-well and related components. Another disadvantage is the requirement of a long tube to guide the tide-staff. Such a long tube is impractical in a location where wind force is appreciable. Yet another disadvantage of this device is that it is not amenable to trouble-free transportation to remote areas and, therefore, not suitable for short-term tide measurements from a multiplicity of remote areas. Still another disadvantage is that the cost of the tide system is very high.
PCT No. PCT/JP91/00610 dated Mar. 4, 1992; and U.S. Pat. No. 5,363,307 dated Nov. 8, 1994 titled “Measuring Apparatus Having an Indicator for Displaying Tide or Tidal Current Data” by Noriyuki Yoshida and assigned to Furuno Electric Company, Limited, Hyogo, Japan describe an apparatus which displays tide data (among other navigational data) and is installable on a ship. The apparatus comprises a multiplicity of navigational aids including a memory having stored tide data corresponding to ages of the moon in relation to points on the earth, data storing means for storing map data of an area, a ship-position measuring means including one of a Global Positioning System (GPS) receiver for inputting the geographical position (i.e., latitude and longitude) of the ship for specifying a given point of the stored map data, a time-measuring means for inputting the date and time at which the latitude and longitude are calculated, a data searching means for reading relevant tide data that is already stored in the memory based on the calculated latitude & longitude and the date & time; and an indicator for displaying tide

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