CaptainCalc Academy & Blog
Technical guides, tutorials, and workflow strategies covering ship stability, celestial navigation, and voyage planning. Build your confidence on the bridge and ensure you get the calculations right every time.
CPA / TCPA Calculator Guide for Collision Avoidance
Learn how to calculate CPA and TCPA, interpret safe passing distance, and use radar plotting logic for practical bridge decisions.
Mastering Under Keel Clearance & Squat Effect
Don't let hydrodynamic suction ground your vessel. A complete mathematical guide to calculating dynamic UKC, factoring in squat effect, vessel speed, and block coefficient (Cb).
How to Calculate Cargo Weight: Draft Survey Guide
A comprehensive look at reading drafts, applying hog/sag corrections, and using hydrostatic tables to determine the exact weight of cargo loaded.
Celestial Navigation: The Intercept Method Explained
Demystifying the Marcq St. Hilaire intercept method. Learn how LHA, Co-Dec, and Zenith distance combine to give you a reliable position line without internet.
Vessel Stability: GM and Intact Stability Criteria
Understanding the critical boundary between safe passage and disaster. A deep dive into Metacentric Height (GM), GZ curves, and Free Surface Moments.
Calculating True ETA: Factoring in Set and Drift
Don't be late to the pilot station. Learn the vector math behind accounting for current (set and drift) to calculate an accurate Estimated Time of Arrival.
Celestial Navigation Calculator: Complete Step-by-Step Guide
Master celestial navigation from sextant observation to position fixing. Learn the 5-step process with worked examples using real vessel data and modern SOFA-based calculations.
Ship Stability Calculations: Formula & Worked Examples
Learn GM, GZ, and heel angle calculations with real container vessel examples. Ensure IMO stability compliance and understand when vessels are in danger of capsizing.
Voyage Planning: Professional Maritime Route Calculator
Complete voyage planning guide: great circle routes, ETA calculations, fuel estimation, and weather routing. Learn how to save $376,000+ on a single voyage through smart route planning.
Understanding the ISM Code: International Safety Management
Ship safety is more than just steel thickness. A comprehensive breakdown of the ISM Code, the Safety Management System (SMS), and the vital role of the DPA.
The ISPS Code: Securing Ships and Port Facilities
The global shield against piracy and external threats. Learn the fundamentals of the ISPS code, the 3 security levels, and the responsibilities of the SSO.
GMDSS Explained: The Global Maritime Distress and Safety System
You are never alone in the middle of the ocean. Understand the GMDSS sea areas (A1-A4) and how lifesaving satellite equipment like DSC, Inmarsat, NAVTEX, and EPIRB function.
Understanding STCW: The Backbone of Maritime Training and Safety
Explore the International Convention on Standards of Training, Certification and Watchkeeping for Seafarers (STCW), covering the 2010 Manila Amendments, Basic Safety Training, and the importance of global maritime standards.
Laytime, Demurrage & Despatch: Complete Calculation Guide
Master laytime calculations: NOR procedures, SHINC/WWD/FHEX clauses, and how to calculate demurrage and despatch with worked examples from real voyage charters.
Charter Party Types: Voyage, Time & Bareboat Charters Explained
Understand the three main charter party types, key clauses (GENCON, NYPE, BARECON), freight terms (FIO, FIOS), off-hire, and how each type affects the master's responsibilities.