Navigational planning and display method for the sailor's dilemma when heading upwind

• US 8,135,504 B2
• Filed: 04/12/2007
• Issued: 03/13/2012
• Est. Priority Date: 04/12/2006
• Status: Active Grant

• Current Assignee: Craig Summers
• Original Assignee: Craig Summers
• Inventors: Summers, Craig
• Primary Examiner(s): Tran, Khoi
• Assistant Examiner(s): Peche, Jorge
• Application Number:
  US12/295,957
• Publication Number:
  US 20090287409A1
• Time in Patent Office: 1,797 Days
• Field of Search: 701/21, 701/201, 701/202, 701/204, 701/23, 701/25, 701/26, 701/207, 701/210, 701/213, 114/39.11, 114/291
• US Class Current: 701/21
• CPC Class Codes: B63B 2035/009 Wind propelled vessels comprising arrangements, installations or devices specially adapted therefor, other than wind propulsion arrangements, installations, or devices, such as sails, running rigging, or the like, and other than sailboards or the like or related equipment
• CPC Class Codes: B63B 49/00 Arrangements of nautical instruments or navigational aids nautical measuring instruments G01C; radio navigation, analogous arrangements using other waves G01S
• CPC Class Codes: B63B 79/40 for controlling the operation of vessels, e.g. monitoring their speed, routing or maintenance schedules
• CPC Class Codes: G01C 21/203 Specially adapted for sailing ships
• CPC Class Codes: G06G 1/0052 for air navigation or sea navigation
• CPC Class Codes: Y02T 70/00 Maritime or waterways transport

Abstract

A method is disclosed that resolves a long-standing seafaring problem of how close to the wind to sail. Sailboats need a convenient way to determine the optimal heading to minimize the Tacking Time to Destination (TTD). Unlike Velocity Made Good (VMG), the method disclosed here allows route planning before the trip, predicts travel time on different points of sail, allows comparison of the optimal tacking routes, and also plots the different routes so that it is inherently obvious that a particular tacking angle is longer and more off-course but will arrive sooner because of the speed on that heading. These principles can be implemented with manual dials that define the distance and speed, to calculate the relative or actual travel time on a leg without using electronics. Software is also described that visually illustrates the current and optimal headings by calculating Tacking Time to Destination before departure.

Claims

1. A method for determining an optimal Tacking Time to Destination by comparing tacking distances and speeds for a boat from a current position to a destination position for different possible courses, and determining an optimal course to minimize the Tacking Time to Destination, said method comprising:

a) estimating additional distances from a current position to a destination position entailed by tacking for different possible courses;

b) estimating boat speed on tacking legs from a current position to a destination position for different possible courses;

c) estimating Tacking Time to Destination based on the distance divided by speed for tacking legs for different possible courses;

d) assessing the optimal course to minimize the Tacking Time to Destination by determining a distance and speed for the course with the smallest travel time;

wherein current and optimal tacking legs are displayed with GPS chartplotter software showing the courses, the distances, speeds and Tacking Time to Destination for each course.

2. The method of determining the optimal Tacking Time to Destination in claim 1, wherein a ranking of the optimal relative course is determined from information on wind angle and bearing to destination.

3. The method of determining the optimal Tacking Time to Destination in claim 1, wherein Tacking Time to Destination in hours and minutes is determined with additional data on boat length and linear distance to destination.

4. The method of determining the optimal Tacking Time to Destination in claim 3, wherein estimates of speed and distance are calculated for both the current route and the optimal route.

5. The method of determining the optimal Tacking Time to Destination in claim 1, wherein a function or look-up table is used to estimate percent of hullspeed on different points of sail of a boat based on either general polar velocity plots or specific polar plots for a particular boat.

6. The method of determining the optimal Tacking Time to Destination in claim 1, wherein a trigonometric formula is used to define the distance, which is a tacking leg Leg I=D′

*sin(a+w)/sin(pi−

2a) and divides this by the speed on Leg 1 to get the predicted time for Leg 1.

7. The method of determining the optimal Tacking Time to Destination in claim 6, wherein the distance on each tacking leg is divided by the speed on that tacking leg, with sum of the resulting quotients giving the overall Tacking Time to Destination.

8. The method of determining the optimal Tacking Time to Destination in claim 7, wherein a travel time is calculated for each different possible tack tacking leg and then choosing the course with the shortest Tacking Time to Destination.

9. The method of determining the optimal Tacking Time to Destination in claim 1, wherein a trigonometric formula is used to define the distance on a tacking leg Leg 2, which is Leg 2=D*sin(a−

w)/sin(pi−

2a) and divides this by the speed of a boat on Leg 2 to get the predicted time for Leg 2.

10. The method of determining the optimal Tacking Time to Destination of claim 1 wherein a Tacking Time to Destination is determined for many possible tacking leg headings, in which an algorithm is used to reduce the number of calculations, by calculating Tacking Time to Destination in larger tacking leg heading intervals before narrowing in for iterations with more specific tacking leg headings once the courses with the smallest Tacking Time to Destination are obtained.

11. The method of determining the optimal Tacking Time to Destination in claim 1, wherein dials are turned manually on a device with moving dials to determine headings and to indicate the angles to the wind and to the destination, to make relative predictions about the course with the optimal Tacking Time to Destination.

12. The method of determining the optimal Tacking Time to Destination in claim 11, wherein numbered scales are present on dials for distance and speed that indicate speed and distance values that are used in a quotient to predict an optimal heading for a current tacking leg.

13. The method of determining the optimal Tacking Time to Destination in claim 1 comprising displaying a current course and an optimal course, wherein the current course and the optimal course are coded by color or other difference in style, along with numerical and text data to allow visual comparison between the current course and the optimal course.

14. The method of determining the optimal Tacking Time to Destination in claim 1 comprising displaying the current course and the optimal course on a GPS chartplotter, wherein the tacking legs are symmetrical or not, with the numerical and text data for each tacking leg displayed separately.

15. The method of determining the optimal Tacking Time to Destination in claim 1 before a trip, using distance predictions and speed from existing polar plots.

16. The method of the optimal Tacking Time to Destination in claim 15, comprising using existing data on wind direction and polar plots to predict speed.

17. The method of determining the optimal Tacking Time to Destination in claim 15, comprising predicting and displaying speed, distance and travel time for a current course in comparison to the optimal course.

18. The method of determining the optimal Tacking Time to Destination in claim 1, wherein a current course and an optimal course are displayed on aerial photos, chartplotters or schematic diagrams to show distances or relative distances, sailing angles and speed on different points of sail.

19. The method of determining the optimal Tacking Time to Destination in claim 18, wherein the displaying of a current course and an optimal course are done before starting or during a course.