Efficiency by RPM
Find the cruise your boat likes best.
Nautical miles per gallon, averaged from the moments your boat actually ran at each RPM.
Restoring your session…NavLog Core · Private beta
The automatic logbook for your boat.
NavLog Core connects to your boat's NMEA 2000 network and records every trip on its own: route, speed, depth, engine hours and fuel. Then NavLog's agent does the paperwork: it builds the maintenance program from your manuals, records the work from your invoices, and files what you tell it.
Run to Port Madison
- Distance
- 18.6NM
- Underway
- 2h 14m
- Avg speed
- 8.3kn
- Top speed
- 22.1kn
- Fuel burned
- 31.4gal
Speed over ground
- 1
07:12Core
Departed Shilshole Bay Marina
- 2
07:48Captain
Took the tender in tow.
- 3
08:26Captain
Port engine low-coolant alarm. Topped up, resumed at 2,800 rpm.
- 4
09:02Captain
Anchored in Port Madison for lunch. 22 ft, sand.
- 5
13:40Core
Back at the slip. Trip closed.
- Connects to
- NMEA 2000 backbone
- Records
- Automatically, every trip
- Maintenance
- Built from your manuals
- Works with
- Claude · ChatGPT · Grok
01The record
Your instruments see everything: depth, speed, engine hours, fuel. Then the screen changes, and it's gone. NavLog keeps it.
Nothing to press
Core opens a trip when the boat gets underway and closes it once you're idle at the dock.
Nothing to remember
Position, speed, depth, heading and engine readings are recorded as they arrive.
Room for your words
Add a line as things happen: a tender in tow, an alarm, the anchorage you liked.
02Vessel analytics
Know your boat by the numbers.
Every trip adds to a history you can actually use: where the boat runs best, what each run cost in fuel, and how the engine hours are adding up.
Ask your record
Plain questions, straight answers.
How much fuel did we burn on the run to Port Madison?
31.4 gal over 18.6 NM on Saturday, about 0.59 NM per gallon. Most of it went on the run home at 3,400 rpm.
Fuel per trip
31.4gal
Where your engines report fuel rate.
Engine hours
1,284.6h
- Port
- 1,284.6
- Starboard
- 1,281.9
Read from each engine's own hour meter, never estimated.
Every track
46trips this season
Every route kept on the chart, ready as GPX.
Sample figures. NavLog shows what your instruments report; a reading that was never sent is shown as missing, not filled in.
03The agent
Hand it the paperwork.
Owning a boat means manuals, invoices and service records. NavLog's agent reads them and keeps the maintenance for you, against the engines' real hours. You don't type in a schedule, and it shows you everything it did.
From the manuals
Photograph the manual. Get the maintenance program.
Engine manual · 3 photos4 tasks, by each engine's own hours
- Oil & filter changeEvery 250 h or 12 mo · Port · StbdDue in 18 h
- Raw-water impellerEvery 500 h or 24 mo · Port · StbdDue in 212 h
- Fuel filtersEvery 500 h · Port · StbdDue in 212 h
- Replace zincsEvery 6 mo · HullDue Oct 12
Due by each engine's own hour meter or the calendar, whichever comes first.
Tell NavLog
Say what you did. It's in the log.
Cleaned the AC raw-water strainer and fixed a small leak in the port salon window.
Filed two entries: AC strainer cleaned (HVAC) and port salon window leak fixed (hull & deck). Undo either.
Typed or spoken, in your own words. Each entry lands on the right equipment in the service log.
From the invoices
Forward the yard's invoice. The service is recorded.
Fwd: Harbor Diesel
Invoice 2211 — port engine service
INV-2211.pdfRecorded Port: Oil & filter change, Sep 20 at 482 h
UndoFiled the invoice under Port engine
Undo
Filed against the right equipment, with the document attached.
Your assistant
Already use an AI assistant? Connect NavLog in two clicks.
What's due on the boat this month?
From NavLog: the port oil & filter change is due in 18 engine hours, and the zincs are due Oct 12.
ClaudeChatGPTGrok
Sign in and allow it. Read-only unless you let it act, and you can disconnect it any time.
Sample documents and figures. Everything the agent does is listed with Undo; when it isn't sure which boat, engine or date, it asks instead of guessing.
04How it works
Install it once. It keeps the log from there.
- Your instrumentsNMEA 2000 network
- NavLog CoreRecords aboard, online or not
- Your accountUploads when in range
- Web and phoneReview, annotate, export
- 01
Install it once.
Connect Core to your NMEA 2000 backbone and vessel power, join it to Wi-Fi, and pair it from the web or the app. No screen at the helm, nothing to open before you cast off.
- 02
Go boating.
When the boat gets underway, Core opens a trip and records as readings arrive. Once you've been idle at the dock, it closes the trip on its own.
- 03
Come back to a finished log.
The trip is waiting when you tie up: the route on the chart, a timeline of readings, and the notes you added along the way. Add a line, export it, or just file it.
05Principles
A record you can stand behind.
A logbook is only worth keeping if it's complete and true. Core is built to be the part of the boat that doesn't forget, and doesn't embellish.
Readings at 08:26
- Depth
- 64.2 ft
- Speed over ground
- 17.9 kn
- Heading (magnetic)
- 308°
- Heading (true)
- Not sent
- Water temperature
- Not sent
- 01
Hands-free by design
No button at the helm and no entry to remember at the end of a long day. The record keeps itself.
- 02
Faithful to the instruments
Core records exactly what your NMEA 2000 network reports. It never fills a gap with a guess.
- 03
Works without a signal
Offshore or out of range, Core keeps recording to its own storage and uploads when it's back in range.
- 04
Shows its work
Everything NavLog's agent does is listed in plain words, with Undo. When it isn't sure, it asks.
- 05
Yours to keep
Every trip has a route, a timeline of readings and your notes. Export any of it as PDF, CSV or GPX.
When the day ends, the details stay.
Paper logs get skipped on the busy mornings, and memory fades by the weekend. Core writes it down every time, whether or not anyone remembers to.
Without Core
No Core yet? Start with the app.
The NavLog app records trips from your phone and keeps your notes and incident reports stamped with time and position. Add Core when you want the boat to keep the log for you.
Create an accountPrivate beta
Put a memory aboard.
NavLog is in private beta with a small group of owners and captains. Join, tell us about your boat, and we'll be in touch about Core.