Methods for Enhancing the Display of Electronic Nautical Charts with Depths Corrected for Tide

• US 20150149081A1
• Filed: 11/22/2013
• Published: 05/28/2015
• Est. Priority Date: 11/22/2013
• Status: Abandoned Application

• Current Assignee: Oscar L. Kramer Jr
• Original Assignee: Oscar L. Kramer Jr
• Inventors: Kramer, Oscar L. Jr.
• Application Number:
  US14/088,310
• Publication Number:
  US 20150149081A1
• Time in Patent Office: Days
• US Class Current: 701/450
• CPC Class Codes: G01C 21/005 with correlation of navigation data from several sources, e.g. map or contour matching G01C21/30 takes precedence
• CPC Class Codes: G01C 21/203 Specially adapted for sailing ships

Abstract

A collection of related methods are claimed for enhancing the display of electronic nautical charts as viewed within an electronic chart display system by correcting the charted depth values for the effects of tide, and displaying actual depths and derivative graphical information, for a specified date and time. Height clearances are similarly adjusted. This will enable new features within the electronic chart display system that will greatly facilitate navigating coastal waters affected by tide. The method is implemented as a computer program.

Claims

1. A method of updating the display of electronic nautical chart represented in vector format (ENCs) so that depths are available with the correction for tide applied. Existing electronic tide tables or computer program, accessible to the Electronic Chart Display System (ECDS)¹ for predicting tide, is referenced given a specific location, date and time, and this tide offset is applied to the depth values to arrive at an updated representation of the coastline and ocean floor for the region.

¹ Throughout this document, the use of the term “

Electronic Chart Display System”

(ECDS), and alternatively “

chart-plotter”

, shall refer to all electronic display systems used for rendering electronic nautical charts for navigation. There are generally two classes of these devices currently in use;

(1) the Electronic Chart System (ECS) used primarily by recreational boaters and some professional mariners;

though usually consisting of a dedicated display device, this may also consist of computing devices commonly used aboard such as laptops, tablets or smartphones, running specialized navigation software utilizing electronic charts, and (2) the Electronic Chart Display and Information System (ECDIS) commonly found on larger ships. The claims and subsequent information herein relate equally to both, and refer to both systems collectively as “

ECDS”

or alternatively as “

chart-plotter.”

2. The method of claim 1, wherein the corrected depth values are used to generate an updated navigational chart with the spot depth readings reflecting the depths corrected for tide, i.e., the depths below actual sea level at any specified time-of-day.

3. The method of claim 1, wherein the displayed depth contours are generated using the depths corrected for tide. The depth contour intervals can be system defaults or programmed by the operator of the ECDS. This functionality will likely require a bathymetry database of higher resolution than that usually available in current government-supplied ENCs.

4. The method of claims 1 and 3, wherein the regions within a range of depths corrected for tide are color coded (i.e. translucent shading), as programmed by the operator of the ECDS, to provide an easily interpreted representation of the depths.

5. The method of claims 3 and 4, wherein the draft of the vessel is programmed and referenced for displaying depth contours and color coding. The result would be a navigational chart customized to the vessel'"'"'s draft where depths, contours and/or shading represent depths below the vessel'"'"'s keel.

6. The method of claims 3, 4, and 5, wherein the ECDS can continuously update the displayed tide-corrected (and draft-corrected if desired) depths, contours and color-shading using the current date and time.

7. Similar to claim 6, wherein the ECDS generates and displays bathymetric information corrected for tide (and vessel draft if desired) for any specified date and time in the past or the future for analysis and planning purposes.

8. Similar to claim 6, wherein the ECDS creates a “

movie-loop”

given a start and stop time and time scale. This movie loop will show the depth values, contours, and shading change with the ebbing and flooding of the tide.

9. A method for computing the tide offsets between primary and secondary tide stations in order to arrive at a best estimate of tide offset for any location to support the method of claim 1.

11. A method of reporting to the ECDS (and thus the operator) the presence or imminence of a grounding risk as determined by considering the vessel'"'"'s draft and actual depths using tide-corrections per claim 1, and predicted ahead of time for the route per claim 10.

14. A method to accept soundings from an on-board, networked depth-sounder to correlate against the tide-corrected predictions of claim 1 to monitor the accuracy of the localized tide predictions and generate accuracy statistics.

15. A method of alerting the vessel operator of significant differences between tide-corrected predictions of claim 1 and that being sensed by the on-board depth-sounder.

10. A customized graphical representation of depth information (i.e. depths, contours, and color-shading) according to above claims, with the additional functionality of applying variable tide corrections along a planned route (or radiating from the vessel'"'"'s current position) using the vessel'"'"'s speed and thus anticipated position to compute the corrected depth information along the vessel'"'"'s path for the estimated time of arrival at each point along the route, so that the operator can more easily decide the feasibility of the route ahead of time. This functionality shall herein be termed “

varying time chart.”

12. A method of correcting the vertical clearances of objects above sea level, such as bridges and power-lines, to reflect actual clearances for specific date and time.

13. A method to permit the operator (via the ECDS human interface) to define additional “

tertiary”

tide stations that can improve the interpolation accuracy of tide offsets (and thus corrected depths and heights) beyond that possible using solely the published primary and secondary tide stations.

16. A method to permit reporting tide-corrected depths and programming desired contour and shading depths as claimed above in either metric or imperial units.