How do hour-based and date-based intervals coexist?

Store both on each component and treat the earlier of the two as the next-due. An oil change might be every 100 hours or 12 months, whichever comes first, which is exactly how engine manuals phrase it.

Should the app ship with standard service intervals?

Offer a starter set for common engines and systems that the owner can edit, but never present them as authoritative. Intervals vary by manufacturer and usage, so the manual wins and the app records what the owner decides.

How to Build a Boat Maintenance Log App with AI (2026)

What a boat maintenance log app needs

Systems and components with service intervals by hours, months, or date
Engine hour meter updates that recalculate what is due
Service log entries with cost, parts, photos, and receipts
Seasonal checklists for launch, haul-out, and winterising
Exportable service history PDF for surveyors and buyers

The screens

Screen	What it does
Boat	Engine hours, what is due soon, and overdue items
Systems	Engine, electrical, rigging, safety, hull, each with components
Log Service	Pick the component, add date, hours, cost, parts, photo
Checklists	Launch, haul-out, winterise, with tick boxes and notes
History	Chronological log, filter by system, export PDF

The data model

Boat: name, make, model, year, engineHours, hullId
System: boatId, name (engine, electrical, rigging, safety, hull, plumbing)
Component: systemId, name, intervalType (hours, months, date), intervalValue, lastServicedAt, lastServicedHours, expiresAt
ServiceEntry: componentId, date, engineHours, cost, parts, notes, photoUris, receiptUri
Checklist: boatId, name, items (label, done, note)

The build prompt (copy this)

Paste this into ShipNative and it becomes a working React Native app with these screens, navigable in a live preview, in about two minutes:

“A boat maintenance log app for owners of sail and motor boats. Boat shows the current engine hours with a quick update field, items due in the next 30 days or 25 hours, and anything overdue in red. Systems groups components under engine, electrical, rigging, safety, hull, and plumbing; each component has a service interval by engine hours, by months, or a fixed expiry date such as flares and life raft service, and shows when it is next due. Log Service lets the user pick a component, enter the date, engine hours, cost, parts used, notes, and attach photos and a receipt photo, and it resets that component’s next-due. Checklists holds launch, haul-out, and winterising lists the user can edit, tick off, and date-stamp when completed. History lists every service entry in order, filterable by system, with a total spent per year and an export to PDF with the boat details for a surveyor or buyer. Works offline at the marina and syncs later. Users sign in so the log survives a phone change. Screens: Boat, Systems, Log Service, Checklists, History.”

Then iterate with small, screen-specific prompts (“make the primary button bigger”, “add an empty state”), preview on your own phone, and export the full Expo project whenever you want. The full method: how to build an app with AI.

How it makes money

An annual subscription per boat priced like a small piece of chandlery, with the first boat and ten entries free. Boat owners spend heavily on the boat and will pay for anything that protects its value; the exportable history that helps at survey and resale is the feature worth charging for. Avoid ads, this audience is small and high-value.

Implementation and the revenue math for every model: how to make money from an app. When you’re ready to ship: App Store and Google Play publishing guides.

Build it now

The prompt above is free to run at shipnative.dev — working boat maintenance log app on your phone today, full code export.

How to Build a Boat Maintenance Log App with AI