Chart Work Navigation | Chart plotting 5047, 5048 & 5056 | Blind & Single PL | Mate’s Exam phase -1

Blind Navigation & Single Position Line (PL) — Full Concept Explained | Mate’s Exam Navigation 🚢
This lesson explains two important chart-work topics often asked in Mate’s Examinations:
1️⃣ Solving a Complex Blind Navigation Problem (0:22–16:51)
A tricky exam scenario where:
• Vessel’s course is unknown
• Initial position is unknown
• Only bearings to lights and ship’s speed are given
The instructor shows how to:
• form a position line from reciprocal bearings
• construct a geometric triangle using two relative bearings
• calculate distance off the light vessel (10.4 miles)
• plot a position circle
• find the ship’s position by intersecting PL + circle
• draw tangent to determine true course steered
Pure geometry + logic — no electronics needed.
2️⃣ Single Position Line (PL) / Blind Navigation (17:11–52:00)
Used when visibility is poor and only one PL is available.
You’ll learn:
• what blind navigation means
• which PLs are suitable (master’s discretion matters)
• what information the question normally provides
(PL + DR/EP + speed + current + wind)
What we must find:
✔ first Course To Steer (CTS)
✔ alteration time
✔ second CTS
Procedure covered step-by-step:
• plot PL and transferred PL
• choose safe CMG (perpendicular where possible)
• draw a safety margin around DR
• use vector triangle to calculate CTS
• find alteration time from DMG & SMG
• calculate second CMG (always along transferred PL)
• recompute second CTS considering current and wind
Also discussed:
👉 situations where perpendicular CMG is unsafe and how to choose an alternative.

🎯 Best For
✔ Mate’s exam candidates
✔ Chief Mate & Second Mate students
✔ Anyone revising blind navigation & PL concepts

Blind navigation
Single position line navigation
PL navigation method
Transferred position line
Course to steer calculation
Alteration time navigation
Vector triangle navigation
Dead reckoning vs estimated position
Perpendicular CMG method
Safe CMG selection
Position circle plotting
Reciprocal bearings navigation
Light vessel distance calculation
Navigation exam blind problem
Mates exam chart work
Chief mate navigation problems
Restricted visibility navigation
Navigation plotting example
Fix from single position line
Navigation geometry plotting
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