Course to Steer

Question 1

What information is required to work out the course to steer?

Answer 1

Required Information: Requires working out or estimating:

• Start Point and Destination Waypoint
• Boat Speed
• Tidal Direction and Speed
• Leeway
• Variation
• Deviation

Question 2

What is the process for working out the course to steer?

Answer 2

Brief Summary

• Plot the start point. (A).
• Find the destination (D).
• Draw the ground track between (A) and (D).
• Extend the line through the destination to B.
• Measure the distance (A) to (D).
• Estimate your boat speed.
• Work out how many hours of tide are needed.
• Plot the tide from the starting position (A).
• Plot the water track (C to I). Boat speed x time.
• Apply variation and leeway.

1. Ground Track

Plot start position and destination. Draw ground track line identified with 2 arrows.

Work out distance to get length of trip and work out tidal set and drift to allow for with boat speed.

2. Tides

Work out to nearest half hour to keep simple.
Find from tide tables then tidal diamond or tidal stream

Draw the tidal vector line from the start fix and identify it with 3 arrows.

Set the dividers to the distance the boat with travel in one hour i.e speed. Use the dividers to see how far along the ground track the boat will travel in this distance. A.k.a the intercept.

Connect the tidal vector to the intercept with line known as the Water Track to work out true course to steer. Identified with 1 arrow.

*If trip longer than one hour then add on subsequent tidal vectors to the original one to create a final water track.

3. Leeway, Variation and Deviation

Leeway - Work out wind direction and speed then add or subtract from course to steer accoridngly. Can show with small course line from start point.

Variation added on west and subtracted on east when converting from true to magnetic course. Same with deviation. Deviation can be obtained from Deviation table.