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.
Passage Nav is the sailing distance calculator built for yacht charters
$6.99 · In-app purchases
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.
A product spec, screen plans, and build steps for your coding agent.
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Combine features and design from your favorite apps.
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What should your app do differently? Your note travels with the kit so your coding agent builds around your idea.
A product spec, phased build plan, differentiation notes, and screen references.
Illustrative example: an invoice app for independent contractors. Your kit is tailored to the app you choose; this is not its generated content.
Goal: Send a clear invoice after finishing a job.
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.
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.
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Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.
Rork plan preview for Passage Nav: map the core Navigation workflow, choose the smallest differentiated feature set, define the data and monetization boundaries, then prototype the riskiest user journey first.
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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
Assumption to check: Real-time traffic updates may not be accurate.
Validate with people who use this workflow before building.
Hypothesis 2
Assumption to check: Limited offline functionality.
Validate with people who use this workflow before building.
Hypothesis 3
Assumption to check: Voice navigation may be unclear or inconsistent.
Validate with people who use this workflow before building.
Hypothesis 4
Assumption to check: User interface may feel cluttered.
Validate with people who use this workflow before building.
Original App Store material. Ratings and screenshots describe the existing app, not proof of demand for your version.
Passage Nav is the sailing distance calculator built for yacht charters. Plot up to ten waypoints on a nautical chart, get your distances in nautical miles — per leg and total — set your speed, and know how long you'll be underway. Works onshore, offshore, online, offline — anytime. KNOW WHERE YOU'RE GOING. You're three days into a BVI charter and someone asks how far it is from the Bitter End Yacht Club to Foxy's. Everyone's an expert on the playlist. Nobody knows the miles. Passage Nav fixes the second problem in under a minute — offline, on your phone, in nautical miles. WHAT IT DOES Pull up the chart, tap your waypoints, and watch the miles add up in real time. Every leg shows its own distance right on the map, with compass bearings a sailor can steer by — S, not 182°. Named anchorages, bays, and ports across 50 cruising grounds are already marked and searchable — just tap where you're going. Slide the speed to your boat's pace and Passage Nav tells you when you'll get there. No setup, no login, no learning curve. You'll have today's route figured out before the anchor's up. WHAT IT DOESN'T Require a login. Track your location. Send marketing emails. Collect usage data. Bill you monthly. Make you download charts before it works. BUILT FOR THE BOAT, NOT THE BROWSER Other distance calculators are web tools built to sell you a charter. Passage Nav lives on your phone, works completely offline, and was designed from the keel up for mobile use. Parchment charts. Brass details. The kind of thing you can pass around the cockpit or post to Instagram. WHAT HAPPENS ON THE YACHT... ...doesn't have to stay there. Save your route as a Passage Log share card — your waypoints, your miles, your time on the water, your caption. Three themes: Classic, Expedition, and Regatta. Dress it with engraved illustrations — anchors, sextants, and ships' wheels are included; optional packs add sea creatures, tall ships, and regional expedition art. Post it before happy hour. Everyone else will want one. PRELOADED REGIONS Passage Nav covers the whole world, because sailors don't always end up where they planned. 16 premier bareboat charter destinations — BVI to Croatia, Society Islands to Seychelles — are preloaded and ready offline before you lose signal. Everything else works when you're connected. TOP DESTINATIONS Not sure where to start? Explore curated 7-day charter itineraries for the BVI, Croatia, Ionian Islands, Leeward Islands, Newport–Nantucket, Seychelles, and Society Islands. PLAN DEEPER AT PASSAGENAV.COM Putting together the full week before you leave home? The web planner at passagenav.com adds multi-day planning, route saving, and export tools. Free to use — no account required. ONE PRICE. NO SUBSCRIPTION. $6.99. Yours forever. Every region, every calculation, every mile — included. The optional packs are one-time purchases too. Nothing in Passage Nav renews. Ever. Passage Nav is a planning tool, not a navigation instrument. The sea doesn't care about your battery. Carry proper charts and nav tools for your waters, and always wear boat shoes.
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Plan a focused first version with your coding agent. These are planning assumptions, not a delivery guarantee.
Choose one audience and one core workflow. Use the kit to agree on its screens, data, and acceptance criteria before building.
Decide which secondary features, integrations, and platform support can wait. Your version does not need to reproduce everything in the original.
Validate external services, specialist technology, data access, and ongoing costs for your chosen scope.
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.