App Overview

EZ Nautical Almanac icon

EZ Nautical Almanac

EZ Celestial LLC · Navigation

You need a Nautical Almanac to do celestial navigation

$9.99 · In-app purchases

PRICE
$9.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
5.0
5 ratings · Top 5%

Evidence scope: No current overall US chart position is available. Category-chart positions shown in discovery are a separate scope. Revenue is a directional model estimate, not verified earnings.

Build your own version

Build Kit

Make this idea yours

A product spec, screen plans, and build steps for your coding agent.

First kit free with a verified email

Add to a Remix

Combine features and design from your favorite apps.

Kit ready. Verify your email to download it.

What's included17 files

A product spec, phased build plan, differentiation notes, and screen references.

  • START_HERE
  • AGENTS
  • EVIDENCE
  • SPEC
  • BUILD_PLAN
  • DIFFERENTIATION
  • skills/
  • screens/
Preview a sample Build Kit No email needed

Illustrative example: an invoice app for independent contractors. Your kit is tailored to the app you choose; this is not its generated content.

Feature spec

Goal: Send a clear invoice after finishing a job.

  • Add a client, line items, a due date, and payment instructions.
  • Preview the total before exporting a PDF.
  • Keep an editable draft if export fails.

Screen plan

Invoice editor: Client at the top, editable line items in the middle, total and preview action at the bottom.

States: Empty draft, validation errors beside each field, exporting, and a retry action that preserves the draft.

Differentiate and validate

Hypothesis: Contractors need faster repeat invoices more than more templates.

First experiment: Test duplicating a previous job with five contractors. Watch where they hesitate before expanding the feature set.

The full kit adds a phased build plan, evidence notes, tool prompts, and implementation guidance. It is a plan for your coding agent, not a finished app.

Usage: Mechanics are fair game; never reuse the original name, branding, assets, or verbatim copy.

JavaScript is required to complete mailbox verification.

Free quick prompt For a smaller starting point

Quick prompt

> SELECT BUILD PLATFORM:

Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.

// RORK SYSTEM PROMPT
Rork plan preview for EZ Nautical Almanac: map the core Navigation workflow, choose the smallest differentiated feature set, define the data and monetization boundaries, then prototype the riskiest user journey first.
            

Preview ready. Verify your email to reveal and copy the full prompt.

JavaScript is required to complete mailbox verification. Return to this prompt preview.

Continue in Rork copies the full prompt to your clipboard first, then opens Rork in a new tab.

Continue in Rork >

Affiliate link: CloneChart may earn a commission at no extra cost

Opportunities

AI-GENERATED OPPORTUNITY HYPOTHESES

These are generated suggestions, not verified review quotations. Check current App Store reviews and speak with users before treating a possible gap as a requirement.

Hypothesis 1

Implement offline map downloads and celestial data caching.

Assumption to check: Limited offline functionality in navigation apps

Validate with people who use this workflow before building.

Hypothesis 2

Add onboarding tutorials and tooltips.

Assumption to check: Difficult to use for new sailors

Validate with people who use this workflow before building.

Hypothesis 3

Offer a one-time purchase for full access instead of subscriptions.

Assumption to check: Subscription fatigue from too many in-app purchases

Validate with people who use this workflow before building.

Hypothesis 4

Integrate user feedback for continuous improvement of calculation algorithms.

Assumption to check: Accuracy issues with celestial calculations

Validate with people who use this workflow before building.

App evidence

Original App Store material. Ratings and screenshots describe the existing app, not proof of demand for your version.

App Store description

You need a Nautical Almanac to do celestial navigation. In today’s digital age, why buy a new book every year when you can buy a digital Nautical Almanac that provides 100 years of Nautical Almanacs (1960 - 2059) for less than half the price of a single year of the book. All data is formatted and organized exactly as you are used to seeing it in the official Nautical Almanacs published by USNO and HMNAO. Here are some things you can do with ezNA that you can’t do with your book: - Generate and use 100 years of Nautical Almanac pages for the years 1960 through 2059. - Easily go directly to the page you want without thumbing through pages. - Highlight the data you are looking for by touching the row and column headings on the page. - Zoom and pan to clearly read the tables. - Using Zoom, pan, and highlight makes the almanac easy to use on a phone as well as a tablet. - Functions are provided to do the necessary table lookups to perform basic Cel Nav activities. - The function pages show all almanac values used in the function with an almanac icon. - Click or touch the icon to go to the correct page with that value highlighted. The concise sight reduction tables are included and the sight reduction function demonstrates how to use them. If you have never used them then you are in for a big surprise. They are amazing! In the format I am generating them, they are a total of 16 pages (32 pages in the official Nautical Almanac). With this few pages and a few extra steps to use them you can still generate sight reductions that are typically within about 1 NM of those produced by Pub 229. Pub 229 has about 400 pages per volume and there is a total of 6 Volumes! ezNA performs all astronomical calculations using the NOVAS 3.1 software from the US Naval Observatory (USNO) and a JPL ephemeris that covers the years 1960 through 2059. Since all calculations are performed in the app, ezNA is fully functional with no dependency on a data connection. Please note that this digital Nautical Almanac is already included in ezAlmanacOne, which is our full celestial navigation solution. There is no need to purchase ezNA if you already have ezAlmanacOne. ezNA is NOT a full celestial navigation solution. It is a digital Nautical Almanac with functions to support using the Nautical Almanac tables. You can only do a single full sight reduction at a time. Using ezNA and manually recording and plotting your reductions you can still generate a fix manually!

Written user reviews are not shown here. Check current App Store reviews >

Screenshots

< Scroll to see more >

Build scope

Plan a focused first version with your coding agent. These are planning assumptions, not a delivery guarantee.

Define the first version

Choose one audience and one core workflow. Use the kit to agree on its screens, data, and acceptance criteria before building.

Set boundaries

Decide which secondary features, integrations, and platform support can wait. Your version does not need to reproduce everything in the original.

Check the hard parts

Validate external services, specialist technology, data access, and ongoing costs for your chosen scope.

SUGGESTED BUILD STACK
React Native
Expo
Zustand
expo-location
react-navigation
TypeScript
BUILD KIT DIFFICULTY
Intermediate

From the Build Kit assessment.

A reliable timeline needs an agreed scope and a technical check. Ask your agent to estimate the phases in BUILD_PLAN.md after that review.