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.
App Overview
Sailing Speed - Boat GPS
No built-in speedometer? No problem! Turn your phone into a reliable speed tracking device for any watercraft
$0.99 · In-app purchases
PRICE
$0.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
N/A
No ratings yet
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.
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Build Kit
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A product spec, screen plans, and build steps for your coding agent.
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What should your app do differently? Your note travels with the kit so your coding agent builds around your idea.
What's included15 files
A product spec, phased build plan, differentiation notes, and screen references.
- START_HERE
- AGENTS
- EVIDENCE
- SPEC
- BUILD_PLAN
- DIFFERENTIATION
- skills/
- screens/
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Illustrative example: an invoice app for independent contractors. Your kit is tailored to the app you choose; this is not its generated content.
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.
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Free quick prompt For a smaller starting point
Quick prompt
Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.
// RORK SYSTEM PROMPT
Rork plan preview for Sailing Speed - Boat GPS: 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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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
Include offline maps and routes for better usability.
Assumption to check: Navigation apps often lack offline functionality.
Validate with people who use this workflow before building.
Hypothesis 2
Design a cleaner, more intuitive layout.
Assumption to check: Users may find the interface cluttered.
Validate with people who use this workflow before building.
Hypothesis 3
Allow users to set custom speed alerts.
Assumption to check: Limited customization options for alerts.
Validate with people who use this workflow before building.
Hypothesis 4
Implement real-time GPS tracking for accuracy.
Assumption to check: Inaccurate data may be a concern.
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
No built-in speedometer? No problem! Turn your phone into a reliable speed tracking device for any watercraft. Perfect for rental boats, kayaks, SUP boards, and small vessels without built-in instruments. KEY FEATURES: • Simple, instant GPS speed tracking • Works on any watercraft - from SUPs to rental boats • No installation needed - just open and go • Works offline - no internet required • Support for knots, mph, and km/h • High contrast display for excellent visibility in sunlight Perfect for: • Rental boats • Kayaking • Stand-up paddleboarding • Small sailboats • Fishing boats • Personal watercraft Whether you're renting a boat for the day or enjoying your personal kayak, get instant speed readings without any extra equipment. The clean, intuitive interface provides essential information at a glance, making it ideal for watercraft that don't come with built-in instruments. Don't let the lack of built-in instruments limit your water adventures. Download now and know your speed on any watercraft!
Written user reviews are not shown here. Check current App Store reviews >
Screenshots
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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.
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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.
