CalcDeck: Maritime Calculators for the Whole Ship
- Reece Smith-ward
- 6 days ago
- 3 min read
If you have ever kept a battered notebook of maritime formulae, flicked between tide tables and a calculator on watch, or tried to remember which correction goes where in a sight reduction, you already know the problem. The working knowledge of a ship is scattered across dozens of methods, and each one has its own steps to remember. Maritime Master CalcDeck gathers that scattered knowledge into a single, tidy place for study and revision.
CalcDeck is a large library of maritime calculators in one app, built for the whole ship rather than one corner of it. Bridge, engine room, cargo office, and cockpit each have their tools here. What makes it useful is that every calculator has clear inputs and shows the method behind each result, so you are not just handed a number. You can follow how it was reached, which is exactly what helps when you are learning.
Tools For The Whole Ship
On the navigation side you can work through course to steer, great circle sailing, CPA and TCPA, set and drift, and ETA. For those studying celestial navigation there is sight reduction, altitude corrections, meridian altitude, and Polaris latitude. Tidal work is covered too, with the rule of twelfths, secondary ports, under-keel clearance, and squat, so you can revise the reasoning behind each figure at your own pace.
Cargo and stability students will find GM, list, trim, tonnes per centimetre, displacement, free surface effect, and grain heeling. In the engine room there is fuel consumption, specific fuel oil consumption, bunker surveys, boiler efficiency, and fresh water generator output. Each one lays out its inputs plainly, so the method stays visible while you practise.
From Commerce To Compliance
CalcDeck reaches beyond the technical too. Commercial tools include voyage estimators, time charter equivalent, freight, laytime, and demurrage, which help you understand the numbers behind a voyage. For regulations and compliance you can study indicative CII, EEDI, EEXI, EU ETS, and MARPOL figures, useful for getting to grips with the frameworks that shape modern shipping.
Safety topics are here as well, with cold-water survival time, search patterns, and lifeboat capacity, alongside a set of weather tools. Smaller vessels are not forgotten either. The small craft section covers anchor scope, hull speed, sail area ratios, and displacement to length, so leisure sailors and students of yacht design have something to explore too.
Free To Start, Yours To Keep
CalcDeck is free to download, and the free set is genuinely generous. All twelve unit converters are included at no cost, along with a wide selection of calculators to get you going. When you want the full library across every department of the ship, a single one-time CalcDeck Pro purchase unlocks it. There is no subscription, so once you have upgraded it stays unlocked.
The app is built to respect your time and your privacy. It works offline, so a poor signal at sea or ashore is no obstacle. There are no accounts to create, no ads, and no tracking. An optional location autofill can save you typing coordinates, and that data stays on your device and is never transmitted. You can also star your favourites, so the calculators you return to most are always close to hand.
A Study Aid In Your Pocket
Maritime Master CalcDeck is available on the Apple App Store for iPhone and iPad. Whether you are preparing for exams, brushing up on a method you have not used in a while, or simply curious about the mathematics that keeps a ship running, it turns a shelf of formulae into something you can carry in your pocket and study anywhere.
A note on how to use it. CalcDeck is a learning, study, and revision aid, and it is not a substitute for formal training or a means of making real navigation, collision avoidance, or safety decisions. The tidal and under-keel clearance tools are for study only, are not a nautical publication, and do not account for weather, surge, wind, or currents. Results are for training and reference and should always be verified against approved instruments, official tables, and the vessel's documentation before any operational use.
