Solent Companion
For sailing the Solent · Android

The local knowledge your chart app doesn't have.

Big ships and their Moving Prohibited Zones, tide gates and local notices for the Solent, in one free Android app that sits alongside the chart app you already use.

Join the closed test See what it does

Android only. Free, no account, no ads. An aid, not a navigator.

The app's map of the central Solent. A 290 metre ship has a red Moving Prohibited Zone box ahead of it, a fast ferry shows its speed line, a green tide gate marks Bramble Bank, and a purple dashed area marks a notice. A caption reads: Advisory only, keep a lookout and monitor VHF 12.

Three questions your chart app doesn't answer

Today the answers are spread across four to six apps, harbour websites and VHF 12. Solent Companion puts them on one screen you can check in a few seconds, one-handed.

  • Is a big ship about to put me inside its MPZ?

    In the Thorn Channel precautionary area, a ship over 150 m carries a Moving Prohibited Zone 1,000 m ahead and 100 m either side. One coming up from astern is easy to miss.

  • What restrictions are in force today?

    Harbour authorities each publish their own notices. Regattas, dredging and works change where you can go, often for just a few days.

  • How much water will I have when I get there?

    Bramble Bank, Lepe Spit and Black Rock see groundings every season. The Day Skipper sum is easy at the chart table and harder in a seaway.

What it does

Built for these waters, and only these waters

Big ships, with the zone you need to keep out of

Large ships show live from AIS, turned to their heading. In the precautionary area, each ship over 150 m gets its Moving Prohibited Zone drawn ahead of it, with a dashed outline for the uncertainty in its reported position.

  • Fast craft and ferries stand out, with a line showing where they'll be in a few minutes.
  • Tap a ship for its name, length, speed and how old its position is.
  • Old positions turn grey and say how many minutes old they are.
A ship's Moving Prohibited Zone drawn as a red box ahead of it, with a dashed outline around it for position uncertainty.
The MPZ box uses the published rules and the ship's reported AIS data.

Tide gates that show the working

Ten of the Solent's known shallow spots, from Bramble Bank and Lepe Spit to Chichester Bar and Hurst Narrows. Enter your draft and the charted depth from your own chart, and the app does the sum with the predicted height of tide.

  • Clearance now or at the time you choose, and when it's above your margin over the next 24 hours.
  • Every answer opens up to show the working, line by line.
  • Not sure which figure to use? The app shows you how to read the depth off your chart.
  • Tide curves for Solent ports, double high waters and stands included, from UK Hydrographic Office predictions.
Charted depth2.1 mfrom your chart
Height of tide+ 1.8 mPortsmouth, 14:30, UKHO prediction
Draft− 1.6 myour boat
Clearance2.3 m

Above your 0.5 m margin

A diagram of a yacht over a shallow spot, drawn to scale: height of tide 1.8 metres plus charted depth 2.1 metres, minus a 1.6 metre draft, leaves 2.3 metres clearance.
The same sum you learned for Day Skipper, worked out for the time you'll be there.

Next to each depth box, a short guide covers chart datum, depths and drying heights, and the small tenths figure. The app doesn't check the number you enter, so the guide helps you get it right.

Local notices, on the map while they're in force

Notices to mariners and events on the water from the Solent's harbour authorities, in one list and as shaded areas on the map. Each one says when it applies and links to the authority's full notice.

  • Areas only show while they're in force, so the map doesn't fill with old ones.
  • Short plain-English summaries; the authority's own notice always applies.
  • In the closed test some notices are examples while the real feeds are added.
A purple dashed area on the map with a calendar badge, and a card reading: Racing, central Solent, in force 9 to 16 August, Read the full notice.

Underway: advisory alerts with your phone in your pocket

Turn on Underway as you leave and the app keeps watch with the screen off. It gives an advisory alert when:

  • your track crosses a big ship's MPZ, or you're already inside one;
  • a fast craft is closing on you;
  • a tide gate near you is below your margin, once you've added its charted depth from your chart.

It stops by itself after 12 hours, and it tells you plainly when it can't alert you, for example with no GPS fix or notifications turned off.

A phone lock screen showing an advisory alert: MPZ in 3 minutes. Northern Jubilee, 290 metres, 11 knots. Your track crosses its Moving Prohibited Zone.

Night mode that keeps your night vision

Night mode dims the screen and turns the controls red, so the display doesn't spoil your night vision. A higher-contrast option is there when you need to read the small print.

Your position stays on your phone

We never receive your position. No account, no ads, no tracking. Your boat details stay on your phone too. Read the privacy policy.

An aid, not a navigator

We'd rather you knew the limits before you download it.

  • Ship positions can be minutes old. AIS can be delayed or incomplete, and not every vessel transmits.
  • Tide figures are predictions. Weather, pressure and surge change the actual height.
  • Depths come from your own chart. Clearance is only as good as the charted depth and draft you enter.
  • Alerts are advisory. They can be late, missed or wrong.

It doesn't replace your chart, your lookout or VHF 12. Keep a proper lookout, monitor VHF 12, and use your own judgement and charts at all times. Read the full disclaimer.

Closed test · spring 2027

Help us test it on the water

We're looking for 20 Solent sailors with an Android phone to use the app for a few weeks before it goes on Google Play. Owners, new skippers and charterers all welcome.

  1. Fill in the form below with the Google account you use on your phone.
  2. We add you to the test and send you a link to install it from Google Play.
  3. Keep it installed for at least two weeks, use it when you sail, and tell us what helped and what got in the way.

We only use your email to add you to the test and to ask for feedback. How we handle your details.

What you'll need

  • An Android phone running Android 8 or newer.
  • A Google account on that phone.
  • A few trips on the Solent during the test.

What you'll get

  • The app before anyone else.
  • A direct line to the person building it.
  • Your local knowledge in the version everyone else gets.

Questions

Is there an iPhone version?

Not yet. We're starting with Android to get it right in one place first.

How much does it cost?

It's free to test, with no account and no ads.

Do I still need my chart app?

Yes. Solent Companion isn't a chart plotter and doesn't plan routes. It sits alongside savvy navvy, Navionics, a plotter or paper charts, and adds the local layer they don't carry.

Does it work without a phone signal?

Partly. The app keeps the latest tides and notices on your phone, and shows the last ship positions it had, with how old they are. Ships aren't live without a connection, and the app says so.

Where does the data come from?

Ship positions from AIS, tide predictions from the UK Hydrographic Office, seamarks from OpenSeaMap, and notices from the Solent's harbour authorities. Tide gate clearance uses the charted depth you take from your own chart.

What does it do with my location?

It uses your position on your phone to show where you are and, in Underway mode, to work out alerts. We never receive it. The map providers do see which area of map you're viewing, as the privacy policy lists, along with everything else the app fetches.

Does it cover the Channel or other harbours?

Not at launch. It covers the Solent, from the Needles to Chichester Bar. Tell us where you'd like it next.