Anchor AlarmSeaTracker chart — Route, Discover, Voyage
The SeaTracker tab is the nautical chart at the heart of AnchorQueen. The
chart never goes away — when you switch tabs and come back, your zoom and
position are exactly where you left them.
The bottom of the chart has a pill bar with three sub-modes:
Route — Discover — Voyage.
Discover
The default mode. The chart is yours to wander.
through compact and expanded states. It shows live motion, chart scale,
position, crosshair range/depth, instrument state, and the Signal K boat.
See Basic UI — the GPS HUD for the complete guide.
"23 dive sites · 8 wrecks · 4 harbours", counted for the patch of sea on
screen and updated as you pan. Tap a count to open the legend that lists
those items. When a layer is on but the water is empty, the strip says so and
tells you what to do about it — "No dive sites in this area — pan wider."
Dismiss the guidance line with its ✕; it returns for the next area.
just these two: Refresh Data re-asks for the exploration layers over the
current view (useful after a slow connection), and Browse Results
restores every legend panel you had minimized.
harbours, anchorages, dangers, wrecks, light sectors, AIS vessels, marine
life, dive sites, fishing watch, ocean data, Wikipedia articles, and your
own captain's marks.
count bubble at passage-planning zooms instead of piling on top of each
other. Tap the bubble — or simply zoom in — to expand it into individual
icons. A lone harbour in an empty bay always shows as its own icon.
articles gather into one violet count bubble; zoom in and they spread into
individual pins, with titles appearing once you are close enough for them
to be legible. When two pins compete for the same spot, the richer article
(one with a photo and summary) wins — the chart never stacks labels on top
of each other.
fastest vessel in each area rather than an unreadable pile; zoom in past
mid-range and every received vessel appears. Vessel name tags appear
once you are close enough for them to be legible. Moving vessels glide
smoothly between position reports. Anchored or moored vessels are drawn
with their ground tackle: a red anchor point ahead of the bow, a line
running back to the vessel, and a lit anchor light — so you can tell at a
glance who is lying to an anchor and roughly where their anchor is. Vessels
whose identity carries a recognisable registry fly that country's flag at
the stern, turning with the hull. Tap any vessel for its details.
trails foam astern — a short curl at slow speed, a long spreading V at
passage speed. It is drawn from the ship's reported speed and heading, not
from where it has been, so it appears the moment a vessel gets under way and
disappears the moment it anchors. Your own boat leaves one too. It is the
fastest way to read a crowded anchorage: everything with foam behind it is
moving.
need.
the panel's icon, name, and a live count badge for the items currently
in view, plus minimize (–) and close (✕) buttons. Drag the
header to move the panel anywhere on the chart — it stops at the screen
edge so the header always stays reachable — and drag the grip in the
bottom-right corner to resize it. Position and size are remembered per
panel (portrait and landscape separately), so your layout survives
restarts. Minimize sends the panel to the Region Button Bar; close turns
the layer off entirely.
shows the depth under the crosshair as you pan.
as a dashed line — handy for crossing traffic. It is a layer you can toggle
(on by default) under Chart Layers → Navigation, where you can also set
its colour and line style.
the course predictor and heading ruler) can be switched off and on with
the double-circle button in the bottom-right map tools capsule, just
below the crosshair and ruler buttons — useful when you want an
uncluttered view of the chart under your boat.
radial command menu fans out around your finger: Captain's Mark
(label and save the spot), Fetch Weather (pin the location and save
its weather report — see
[weather pins](#weather-pins-chart)), and Plan Route (jump straight
into Route mode with the first waypoint dropped). Tap a command to run
it, or tap anywhere else to dismiss. In Voyage mode the same gesture
offers Sail to Here and Fetch Weather; in Route mode it drops
the waypoint directly, no menu.
seamarks, harbours and marinas, dive spots and reefs, marine-life sightings —
carry a Save as Waypoint action (the labelled pin in the card's top bar)
that drops a named, editable waypoint at that spot. Shore facilities such as
dive centres are not navigable points, so they omit it — you can still
bookmark them with a Captain's Mark or fetch their weather.
Use Discover to learn an area, scout an anchorage, or browse points of
interest.
The AIS Vessels panel
Tap the AIS Vessels button in the Region Button Bar (the ferry icon) to
open the traffic list for whatever is currently on screen. It is a floating
panel like every other legend — drag its header to move it, drag a corner to
resize it, and it remembers where you put it.
What each row tells you
drawing you see on the chart, so the list and the chart speak the same
language. Anchored vessels show their ground-tackle symbol here too.
the flag of its registry, worked out from the MMSI itself.
badge for anything unusual about the ship's status — Anchored, Moored,
Aground, Fishing, NUC (not under command), RAM (restricted in its
ability to manoeuvre), or SART (a distress beacon).
old, so a stale contact never looks live.
CPA — how close will it pass?
When AnchorQueen has your own position, every row also carries a CPA
badge: how close that ship will come if you both hold your present course and
speed, and how many minutes until it happens. This is the number that matters
in traffic — a ship twelve miles away closing fast is more your problem than
one two miles away that is opening.
is tinted, and an AIS-SART always counts as red.
The badge is left out entirely when the ship is already drawing away, or when
your own position is not yet known — AnchorQueen would rather show nothing
than a made-up number. CPA assumes nobody alters course; it is a warning to
look up, not a substitute for looking out of the window.
Sorting and filtering
The chips across the top reorder the list by Risk (the default — closest
CPA first), Range, Speed or Name. The funnel button filters by
vessel type, so you can watch commercial traffic and ignore the weekend
pleasure fleet. The eye button hides or shows AIS on the chart; if the layer
is off, the panel says so and offers a one-tap Show.
Tap a row to open the vessel's full details, or the crosshair on the right to
centre the chart on it.
Vessel details
The sheet opens with the ship as the chart draws it: the hull for its type,
turned to its heading inside a compass rose, trailing foam when it is making
way and showing its ground tackle when it is at anchor. Under it sit the
vessel's name, its flag — the ensign and the country's name, both, because
several flags are hard to tell apart at a glance — and a badge saying what the
vessel is doing: under way on engine, under sail, at anchor, fishing, aground,
with its speed alongside. Contacts that broadcast no navigational status, which
is most small craft, get Making way or Not making way from their speed
rather than no badge at all.
Below that is what the ship broadcasts about itself — MMSI, IMO, call
sign, position, motion, dimensions, destination — plus a Registry section
that looks the vessel up in an independent record: year built, builder, gross
tonnage, owner and operator, home port, and a photograph where one exists.
Everything a ship transmits over AIS is typed in by its own crew, and it is
often stale or simply wrong. Where the registered name differs from the
broadcast name, both are shown — the disagreement is worth knowing about.
Many small craft appear in no public registry at all; the sheet says so
plainly rather than leaving the section blank.
Where a ship's registry keeps its name in its own writing system — Chinese,
Korean — that name is shown alongside the romanised one. Some records also
state the AIS class: a Class B transponder transmits less often and at
lower power than Class A, which is worth knowing before you lean on the
position of a contact that has not updated recently.
Registry data is compiled from open government sources — Wikidata, NOAA
MarineCadastre, France's ANFR, the EU Fleet Register, Finland's Traficom,
Taiwan's Maritime and Port Bureau and Korea's Ministry of Oceans and
Fisheries. Each record credits the sources it was built from, and photographs
carry their own individual licences, shown beneath the image.
Live instrument readout
If you have connected an NMEA instrument source (a Wi-Fi gateway,
Bluetooth pod, or Signal K server — see [Settings →
NMEA](settings.html#instruments)), the GPS HUD grows a live instrument section.
It appears only while a source is connected; on a built-in-GPS device the HUD
is unchanged.
RETRY (amber), or NO SIGNAL (red) — the transport (TCP / UDP / BLE),
and how long ago the last data arrived. The age keeps counting up if the feed
goes quiet, so a frozen "12s ago" is your cue the gateway stopped sending.
water shoals), wind (apparent or true speed with its angle), and — when
you tap the card to expand it — heading, speed through water,
sea temperature, and CUR. The tiles wrap into rows on narrow screens,
and only the values your instruments actually send appear.
speed through the water and a heading, AnchorQueen subtracts the water vector
from the ground vector and shows what is left: the set (the direction the
current is flowing towards) and the drift (its rate in knots). It is the
difference between an ETA that holds and one that slips by an hour, and no
single instrument reports it. It appears only when both vectors are present,
and stays hidden below 0.2 kn, where the answer would be calibration error
rather than tide.
Trend graphs
Expanding the GPS HUD reveals a row of trend graphs that scroll as new
readings arrive. Each one carries its own scale so it reads as an instrument
rather than a decoration: the live value sits at the top right, the window's
low and high sit underneath, and where it means something a small arrow gives
the rate of change.
metres per minute. The rate turns amber when the seabed is coming up.
This is the number that tells you a bank is rising under you before the depth
itself looks alarming.
building or a gust cycle before it reaches you.
The speed graph does not need instruments. If no Signal K server is
connected — or the link drops mid-passage — it keeps drawing from your device's
own GPS fix, and a small tag beside the title says which feed you are looking
at: SK for the boat's log, GPS for the handset. The trace is
deliberately not cleared when the link changes hands, because your speed over
ground does not change when the boat's Wi-Fi does.
The speed graph also appears in Voyage mode, below the position chip, where
"are we holding our planned speed?" is the live question.
Your fleet on the HUD — REMOTE
When you are in a Remote channel — a private
channel or a flotilla — the GPS HUD grows a second link section directly below
the instruments, marked RMT. It speaks the same language as the instrument
row above it, and like that row it appears only when a channel is joined: if
you never use Remote, the HUD is exactly as it always was.
(green), LINK… (amber, joining or reconnecting), QUIET (yellow —
you are in the channel, but nobody has sent a fix recently), followed by the
channel name and its type, and a ticking "last fix" age that turns amber past
10 seconds. Connected and talking are not the same claim, and the HUD
keeps them apart.
Each chip carries the boat's photo inside its status ring — teal at
anchor, indigo under way, red dragging, grey offline — a corner badge, the
name, and the live distance from you. The ring colours match the
chart fleet strip and the halos on the chart,
so the same boat never looks like two different boats.
boat sprite turned to its heading, name and status, live coordinate, and a
motion line reading HDG · SOG · BATT · YOU↔BOAT. Tap that row and the
chart flies to the boat at your current zoom. Tap the selected chip again to
go back to ALL.
summary — how many are live, anchored, under way, dragging — and tapping it
frames the whole channel on the chart with the connection web drawn in.
channel reports a dragging anchor, whichever vessel you had selected. Tap it
and that boat is selected and on screen in one move.
Expand the card (tap it a second time) and the REMOTE section adds value
tiles and actions:
(amber below 30 %, red below 15 — a watched boat whose phone dies stops
reporting drift at all), the FIX age, and RADIUS when the boat is on
anchor watch. In ALL mode the tiles count the fleet instead.
boat re-centres the chart on it. It stands down on its own if that boat goes
quiet, and whenever you select a different vessel.
live metrics), the same sheet the fleet board uses.
every anchored member's. In a crowded anchorage twenty overlapping swing
circles are unreadable; this is how you answer "is that boat still sitting
in its circle?". Available when the boat is on anchor watch, and it releases
when you change selection or collapse the card.
On the collapsed rail the section shrinks to a single RMT·n chip beside
the instrument chip, where n is how many boats are currently live. It is teal
while the channel is healthy, amber while joining, grey when everyone has gone
quiet — and red with a ⚠ while any boat is dragging, so the alarm survives
collapsing the card.
Satellite & Hybrid Base Map
You can overlay high-resolution satellite imagery directly under your vector nautical chart layers to get a complete photographic and metric view of coastal waters.
To enable this:
This overlays high-precision soundings and depth hazard lines directly over real-world coastal structures, making it extremely easy to plan entrance channels to unfamiliar marinas (such as the Hurricane Hole Marina in Stock Island, Florida).
Route
Route mode replaces the HUD with the Route Panel at the bottom.
Entering Route mode with no active plan lands on your Saved Routes — start
from a known voyage, or begin a new one right from the header row: Plan New
Route drops the first waypoint at the chart centre, Search looks up the
destination by name (results ranked water-first), and the location button
arms the departure at your live position.
Command Rail sits on the left edge in Route mode. Tap Drop DEP and
the chart waits for you — a banner reads *"Tap the chart to place
departure…"*. Tap (or press and hold) where you want it and the departure
lands there with a ripple. Tap the lit command again, or the ✕ on the banner,
to cancel without placing anything.
rail lights Drop ARR and the banner changes to *"Tap the chart to place
arrival…"* — one command press per point, never two. Your next tap sets the
arrival and the passage plans itself.
icons; drag it sideways (grab it anywhere — the small pill on its right
edge shows where) and it widens to show each command's name. It remembers
which way you left it.
three commands — Drop DEP, Drop ARR, Routes. Reverse, Clear, Save Route and
Add Waypoint appear as your plan earns them, and step away again when it
doesn't. Nothing sits there greyed out.
fill in as points land, and the ringed one is the step the rail is waiting
on.
Add Waypoint inserts a via-point between them and the passage re-plans
through it. The command stays armed, so a four-leg passage is four
taps — no re-arming between them.
notice rather than silently making a route you can't sail.
capsule, the arrival as a red ARR capsule, and every via-point as a
numbered cyan circle — the number is the leg it closes. Re-dropping an
endpoint slides it to its new spot instead of jumping, so you can see
what moved.
keeping every leg), Clear, Save Route, and Routes (reopens the
saved-route list).
Hybrid A*-APF & Relaxation Cascade
The routing engine operates off the main thread to ensure absolute UI responsiveness, resolving paths in three logical stages:
* Strict Mode: Enforces full draft + safety clearance along the entire route.
* Shallow Mode: If Strict fails, the planner relaxes clearance rules near the endpoints while warning you of potential draft exposure.
* Best-Effort Mode: Relaxes clearance limits entirely near docks to guarantee that a continuous route is generated, rather than aborting with a routing error.
S-52 Chart Standards & Cross-Track Distance (XTD)
SeaTracker adheres to IHO S-52 specifications for ECDIS chart display and IEC 61174 operational standards for route monitoring, giving captains professional-grade visual clarity and safety assurance.
Polyline Color Conventions
#DC299E / #FF00FF): The international standard token for planned routes. Planned passages created by the captain always render in solid magenta so they stand out clearly against bathymetric depth contours and seamarks.#FF2E91): Routes planned or suggested by Jules (your AI crew member) are rendered in a distinct hot-pink line, letting you instantly distinguish AI-authored passages from your own.#9AA0A6 / Speed Gradient): Past tracks recorded during active navigation render in neutral grey or speed-gradient colors (green → yellow → red), visually separating where you have sailed from where you plan to sail.[2, 2] Dashed Lines): Straight-line chains without a computed depth-aware path appear as dashed ghost lines so un-routed chords are never mistaken for validated passages.Cross-Track Distance (XTD) Safety Corridor
Per IEC 61174 §8.2, planned routes display a Cross-Track Distance (XTD) safety corridor around the route line:
[6, 5] dash pattern) marking the outer boundaries of the XTD corridor ($185\text{ m} \approx 0.1\text{ NM}$ by default, customizable per route).Thin-Water Hazard & Tide Warnings
Each leg of a planned route is dynamically evaluated against vessel draft and predicted tide levels:
#F23030): Grounding danger — effective tide-corrected water depth is less than your vessel's draft.#FFA61A): Caution — water depth is less than your draft plus minimum safety clearance.Dock to Dock
At the top of the Route Panel a two-way switch picks how you build the
route:
many anchors as you like; the app routes between each pair.
harbour to that harbour" passage.
In Dock to Dock the panel shows two slots:
by name. You can also tap the location icon to use your current
position, or the ferry icon to drop in the nearest harbour.
A is set. The moment you choose a departure, the destination picker
opens automatically so you can search straight for where you are going.
The picker lists harbours & marinas first, with other places below, and
shows the distance from your current view. Once both docks are set the app
auto-routes between them around the shallows, just like Free-form.
confirm the pick — departure (A) recenters the view just like
destination (B).
departure and destination — the route re-plans instantly.
Captain's Library
The Capt's Routes entry in the side menu opens the Captain's Library —
one searchable place to manage everything you have saved or collected:
editor; swipe to delete. Long-press for the full action menu: View on
Map, Start Navigation, Duplicate, Reverse Direction,
Export GPX, and Passage Plan (PDF) — the printable A4 passage
plan, straight from the list, no detail sheet required.
and anchorage dwell time; the scope button flies the chart to it.
swipe to delete.
(distance, duration, track points). Tap one for the full passage log
with stats and the ETA calculator.
A search box, sort menu, and live result count sit above the list. The
⋯ Advanced menu adds Import GPX and Manage Folders.
Importing a GPX file. Pick the file and the import runs in the
background behind a small Importing GPX card that counts the points as
they are read, then the routes as they are built. A long recorded track can
hold tens of thousands of points, so the counter is there to show the app is
working rather than stuck — wait for the card to disappear. The same card
appears when you import a GPX into the route planner.
In landscape the library opens in the right details panel, so you can
manage routes while the chart stays in view; in portrait it opens as a
sheet.
Voyage
Voyage is active navigation. A single press-and-hold turns a spot on the
chart into a planned passage you then choose to start. Until you've sailed
a few voyages, an on-chart hint reminds you of the gesture.
your finger; hold until it completes.
from your current position (A) to that point (B) around shallows and
land. Tap the pill's ✕ to abandon the plan. If something prevents a
route — no GPS fix, a destination on land, a point too close to the
boat — the pill says so right there.
the distance and estimated time, and the planned path draws on the
chart as a dashed preview line — pan and zoom freely to inspect it.
(your track, waypoint arrivals, and stats) start, the depth and weather
graphs fill in, and nearby chart objects drop at both ends. Tap
Dismiss to discard the planned route; nothing is started or saved.
Navigation quick commands. The round button in the right-hand column
fans out Voyage's own command set: Anchor (drop or lift the anchor
watch), My Vessel (drop your vessel pin), Course Up (turn the chart
so your heading points up the screen, instead of north), and Follow
Vessel (keep the camera on the boat; tap again to let the chart stay
where you leave it). The last two light up while they are engaged. These
commands appear in Voyage only — Route and Discover have their own sets.
Because you confirm with Start, a stray long-press never launches a
voyage on its own. Both endpoints are named after their nearest place. If
the boat has moved meaningfully while the card sat waiting, tapping
Start quietly re-plans from where you actually are before navigation
begins, so the route always starts at the bow — not where it was a few
minutes ago.
Already navigating? A press-and-hold while a voyage is running doesn't
start a new one — it proposes inserting a waypoint at that spot and
reroutes from your current position through it, pending your confirmation.
Active Navigation HUD
While navigating, one card sits at the top of the chart with four
tap-to-switch sections:
a cross-track error bar.
remaining, and your position in the route.
type buttons to switch which graph is shown. Depth is always free; the
Wind, Waves, and Tide forecast graphs are a Pro feature — on a
Free account those strips show a locked "Pro feature" upsell instead of a
curve. See the Store to unlock them. Wind draws gust as a
fainter dashed line over the wind line, with wind-direction arrows. Each
graph shows live forecast data along the route, waypoint marks, and a
distance scale. A white dot tracks your current position; drag the
graph to scrub a white dot along the route on the chart — it snaps back
to your live position after a moment. Tide shows the predicted
harbour tide height along your route, drawn around a mean-sea-level line
(the curve dips below the line at low water); where tide predictions
aren't available for an area the graph shows a gap rather than a guess.
Use the ‹ › arrows in the HUD header to step to the previous or next
waypoint; a short banner confirms the new target. The minimize button
(⤡) in the HUD header collapses the whole card to a small NAV · WP
chip; tap the chip to bring it back. The place-name badge tucks in directly
beneath the HUD so the rest of the chart stays clear.
The command window at the bottom (depth scrubber + playback controls)
has three sizes — tap its stage button to cycle full → compact →
minimized and back, freeing chart space when you don't need it.
In landscape the HUD is width-capped to the leading side so it never eats the
chart, and panels you open from it (route detail, passage plan) dock into the
right details column instead of covering the map — the same split behaviour as
the [Captain's Library](#captains-library).
Stopping & rerouting
reads STOP while you navigate. Tapping it asks you to confirm
before ending guidance, so a stray tap can't drop your route.
slides in showing the time and distance you would save. Tap Accept
reroute to switch or Keep current — it also dismisses itself after a
few seconds if you do nothing.
Finding a place
Tap the search icon in the top bar to open the search panel. On iPhone
it opens as a full-screen search surface with the results filling the
display; on iPad it floats as a compact palette. It has two tabs:
What Map Search looks through
One search box queries everything at once and groups the results by where
they came from, your own data first:
| Group | What it finds | Where it comes from |
|---|---|---|
| Captain's Marks | Your saved pins, dive sites, and saved articles | On your device |
| Routes | Your saved routes (by name) | On your device |
| Waypoints | Your named waypoints | On your device |
| AIS Vessels | Live ships near you, by name, MMSI, call sign, type, or destination | Live AIS feed |
| Harbours | Marinas and harbours from the bundled database | On your device |
| Seamarks | Charted buoys, beacons, and lighthouses | On your device |
| Places | Bays, islands, towns, landmarks, addresses | OpenStreetMap (online) |
| Places (Google) | Marinas, businesses, and points of interest by name, where available | Google Places (online) |
| Harbours (Online) | The worldwide marina/port database — thousands of marinas with facilities, shelter, and approach depth | OpenSeaMap (online) |
| Explorations | Wikipedia articles about places near you | Wikipedia (online) |
Your own data and live AIS appear instantly as you type. The online
groups join a moment later — they start once you've typed three letters and
the app waits for a short pause in your typing before reaching out, so it
isn't firing off a request on every keystroke. Online results are cached,
so repeating a recent search returns instantly and still works when you later
go offline.
Reading a result
Each row shows the name, a short subtitle (vessel details, route length,
harbour facilities, and so on), and — when the app knows your position — the
distance in nautical miles. A small dashed-square icon means the place
has a known boundary, so flying to it frames the whole area rather than a
single point.
When a routing chart is installed for the area, each result also carries a
water verdict: a cyan waves icon means the spot is on navigable water
for your vessel; an orange mountains icon means it is inland (or too
shallow), so using it as a route endpoint will snap it to the nearest
coast. When you open search from a Route A/B slot, on-water results are
listed first within each group.
Tap a result (or its → button) to fly the chart there and drop a pin at
the spot, labelled with its name so the location stays marked after the
camera settles. Tap the pin to clear it. Tapping a route result reveals
that route and frames it end to end; tapping a Wikipedia result also opens
its article panel.
Every place result also carries a purple Route here button — one tap
starts a passage to it: the app switches to Route mode, sets your live
position as the departure, snaps the destination to navigable water if the
place is inland, and plans the route immediately. The same Route here
action is available on harbour and seamark info cards and on article panels,
so anything you can look at, you can sail to.
Recent searches
When the box is empty the panel shows your Recent searches. Each row
carries a small badge showing who ran it:
to find somewhere, she searches the very same sources listed above, so a
marina she finds lands here ready to tap.
Tap the ✦ Jules chip above the list to show only the places Jules found.
Clear History wipes the recent list and the offline cache.
> All online sources are not for navigation and may be unavailable
> without a connection — your charts, marks, routes, and the bundled harbour
and seamark data always work offline.
Choosing the chart style
The base-map style and depth palette live in the chart itself — open the
Chart Layers sheet from the bottom-right corner and pick them under the
Maps tab (see [Chart Layers](#layers)). The choice is global and persists
across launches. A fresh install opens on the OpenStreetMap base map, so
land, towns, and coastlines are visible worldwide before you download
anything; the moment your first chart pack finishes installing — including
the free worldwide base map — the app switches once to Nautica Day (with
the reverse NOAA palette), the style tuned for day-time clarity at anchor.
Pick any base map yourself and that choice sticks: the automatic switch
never overrides an explicit selection. The only
chart-appearance control in Settings is the
Auto-match Device Appearance toggle, which flips the palette between its
day and night siblings when iOS switches light/dark mode — it does not choose
the base map.
Chart Layers panel
The Chart Layers sheet is where every overlay is switched on or off. It is
organized into five tabs across the top so you jump straight to what you want
instead of scrolling one long list:
Night, Dusk (the official S-52 twilight colour table), and
Paper (the traditional paper-chart look) — plus third-party providers),
the depth-palette theme, the Depth & Bathymetry group (Depth Contours
and Depth Polygons are on by default so a fresh install opens to a legible
bathymetry chart; the heavier Water Depths / EMODnet fill stays off until you
switch it on, and changing the chart theme re-shows the contours and polygons
if you had hidden them), and
the vector base-map sub-layers (roads, buildings, labels, POIs, boundaries).
Start here to set how the chart looks.
(seamarks, administrative regions, [traffic separation schemes](#tss),
customs, raster charts) and the offline S-57 ENC stack you unlock by
installing a region (soundings, channels, hazards, seabed).
Country borders and maritime zones (EEZ) have no switch — they are
always drawn as overview context and disappear on their own once you zoom
past harbour-approach scale, so they never sit on top of chart symbology
where it matters.
seamarks, harbour database, weather, and the exploration layers
(marine life, dive sites, ocean data). The Global Fishing Watch effort
heatmap is not listed here — it lives in the Merconi tab's
Fishing lens and has no separate Layer-Control switch.
AIS API feed (aisstream.io / VesselAPI) with provider and connection
status, and the Fleet (Remote Sync) group — captains sharing live
position through a SafeAnchor remote channel, with a brief showing the
channel name and how many vessels are synced. The feed always starts each
launch on the default aisstream.io provider; VesselAPI is used only as
an automatic failover (if aisstream.io stays unreachable) or when you pick
it yourself, and that choice lasts for the session only — the next launch
returns to aisstream.io. When you pan or zoom, the ships already on screen
stay put while the feed re-subscribes to the new area in the background —
they refresh in place rather than blinking off and back on. If the feed
provider goes down at its end, AnchorQueen retries for a couple of minutes,
then stops and shows Live AIS Unavailable in the vessel list rather than
retrying forever in your pocket. It tries again on its own about ten minutes
later, and if you have VesselAPI configured the feed fails over to it within
half a minute. The ships last seen fade off the chart as they go stale rather
than sitting there looking live. Charted objects, your own tracks, and the
anchor watch are unaffected; only live ship traffic pauses.
AIS tab for live positions of other AnchorQueen captains broadcasting on
the public beacon near where you're looking. They show on the chart with
an amber ring (so you can tell them apart from your own flotilla,
which is teal, and from raw AIS, which has no ring) and update live while
you're zoomed in. A brief shows how many are in view. It starts off
because keeping the live feed open uses data — turn it on when you want to
see who's anchored around a busy bay.
line, anchor history) plus the appearance of the anchor-watch rings,
own-ship lines, and per-mode crosshair colours.
The bolt menu in the top-left corner has Show All Layers and
Hide All Seamarks shortcuts, reachable from any tab.
Soundings — depth numbers on the chart
Installed regions print spot depths (soundings) the way a real chart does:
an integer with a smaller tenths digit beside it (5₄ means 5.4 m). Numbers
shallower than your draft plus safety margin (from your
boat profile) are drawn in the warning colour so the depths
that could ground you read at a glance.
The Charts tab → Soundings group controls how they appear:
spaces them the way an ECDIS does: roomy at passage-planning zoom, dense
while piloting, and depths safely beyond your draft step back into a quiet
grey so the shallow digits stand out. Pick Sparse, Balanced, or
Dense instead if you prefer one fixed spacing at every zoom.
contour labels (Day Bright, White Back, Black Back, Dusk, Night, or a
custom colour). Auto follows the active base map and depth theme.
Anchorages, marinas & harbours
Anchorages and marinas are the places you actually sail to, so the chart
gives them front-row treatment:
glyphs, drawn larger than ordinary buoys and beacons, and they stay legible
from passage-planning zoom instead of appearing only when you're almost on
top of them. Names appear beneath the symbols from mid-zoom — no more
tapping every anchor to find out which bay it marks.
facilities collapse into a single harbour badge with a count. Tap it to zoom
in and spread them out.
(not just a point), the chart shades its extent with a translucent tint and
a dashed boundary once you zoom to harbour scale — you can see exactly where
the designated anchorage begins and ends. Tap inside the area for details.
plus the OpenSeaMap harbour database, which also powers
[Map Search](#search) results for harbour names and links to community
pilot-book pages where available.
Marinas and Harbours under the Charts tab's seamark group.
action: harbours, marinas, anchorages, all seamarks (lights, buoys,
beacons, wrecks, landmarks…), dive sites, ports of entry, and saved
waypoints. One tap pins the place as a
[weather pin](#weather-pins-chart), fetches its meteogram report, and saves
it for offline reading; the button then shows Weather Report Saved with
the report's age, and tapping it re-opens the saved report. This in-app
report is the only weather path on these sheets — the old external
OpenSeaMap meteogram link (online-only, left the app) has been retired.
Weather pins on the chart
Locations you pin for weather (from a POI detail sheet or the
[Meteo tab's avatar strip](meteo.md#weather-pins)) render as round weather
badges on the chart — the current sky glyph on a blue disc, with the pin's
name and a compact temperature · wind · age caption beneath. The badges
appear on every chart surface, including the SafeAnchor anchor-watch
chart, and update as reports refresh.
from the app's first fetch — shows as a My Position badge that moves
with your weather fetches, so the anchorage you're sitting in always has
an aged report on the chart. Remove it from its report sheet if you'd
rather not see it; the Meteo tab's + brings it back.
turns amber as the report ages and the whole badge greys out once it is
older than 12 h. The age in the caption counts up (35m, 3h, 2d).
alerts, and the full meteogram for that spot, plus Refresh / Remove.
is fetched while a saved report is still current, so pinned weather is
kind to your data plan.
Traffic Separation Schemes (TSS)
In busy waters, shipping is funnelled through Traffic Separation Schemes —
one-way lanes for opposing streams of traffic, divided by a separation
zone you must keep out of. AnchorQueen carries the IMO/IHO scheme data
offline and draws it on the chart; the layer lives under Chart Layers →
Charts and is on by default, because the rules of the road
(COLREGS Rule 10) require you to treat these zones with care.
On the chart the lanes show the direction traffic runs; the separation
zone is the strip between opposing lanes.
While you are under way, AnchorQueen watches your track against any scheme you
are near and raises a banner:
way the lane runs before you commit.
Rule 10 says cross as near to a right angle as practicable — straighten
up toward 90°.
direction of flow, a Rule 10 violation. Alter course.
The banner is always shown on screen while an alarm is live; an OS
notification is also posted when the app is in the background. Anchoring is a
special case — Rule 10(g) forbids it inside a separation zone — and is handled
by the anchor watch, see
SafeAnchor → Anchored in a separation zone.
Turn the alarms off (the layer stays) under
Settings → Nav → Safety Alarms.
S-52 Chart Rendering & Local Vector Tiles
At its core, AnchorQueen uses a customized MapLibre GL Vector Compilation Engine designed to provide a highly interactive, 60fps chart experience entirely offline.
* S-52 Day, Dusk & Night Charts: Conforming to IHO (International Hydrographic Organization) Presentation Library standards, the app translates S-57 ENC feature attributes (depth contours, light sectors, buoys, restricted areas) dynamically using custom styling stylesheets (Nautica Day, Nautica Night, Nautica Dusk — the authentic S-52 Dusk colour table — and Nautica Paper, the traditional paper-chart presentation).
* Offline Vector MBTiles: Raw bathymetry, land outlines, and marine boundaries are compiled using optimized mathematical simplifications (tippecanoe) into highly compressed, local MBTiles packages (adminland.mbtiles, maritimezones.mbtiles, admin_places.mbtiles). This reduces resident storage from gigabytes of raw GeoJSON down to a few hundred megabytes, preventing out-of-memory crashes on mobile devices.
* Bundled SDF Glyphs: A fully offline Signed Distance Field (SDF) font package covers Latin, Cyrillic, Greek, and Turkish character sets, enabling real-time font rendering at any tilt and zoom angle.
* Keel Sounding Lookups: Tapping the crosshair triggers a local spatial Kd-Tree lookup to query soundings and physical hazards under the cursor. This operation runs off the main thread to prevent map stuttering during fast pans.
Recording a track
Open the Tracking sheet from the chart's action menu to start recording
a track. Tracks are saved as GPX files you can keep, share, or replay later
from Capt's Notebook.
Chart downloads for this area
The Charts button (map icon, in the right-edge camera column just below
the zoom buttons) is the chart's download scout and the health check for
the charts you already own. Tap it and a small panel lists what needs your
attention right now:
don't have it yet,
different one (planning a Caribbean season from an Aegean anchorage shows
both),
recommended first download. It paints survey-grade land and coastlines at
every zoom level worldwide, which is why the app nudges you toward it: on
a fresh install a small bubble appears next to the Charts button for a few
seconds ("Free world map available — tap to add") and then gets out of
your way,
chart covering the area is installed but its subscription has lapsed, and
covering chart has been published.
A chart you have installed, licensed, and up to date never appears — the
panel only ever shows actionable rows. Download rows show the region's name
and size; tapping any row (or Browse all charts) opens the
Store's Charts section, where downloads, renewals, and
updates all run.
The expired notice carries an inline Renew button — tap it and the
purchase sheet raises right there; the moment the renewal completes the
notice clears itself. (Tapping the rest of the row still opens the Store if
you'd rather browse first.)
The button pulses when something new needs attention — an uncovered
area, a lapsed subscription, or a fresh update. Opening the panel once
acknowledges it — the pulse stops and a small dot remains as a quiet
reminder. A chart moving into a new state (say, its subscription lapses
later) pulses again. In landscape the panel keeps a slimmer footprint and
its list scrolls, so it works the same either way you hold the device.
When a chart subscription expires
An expired chart is not taken off the screen — it keeps rendering for a
grace period so you are never left staring at blank water. What changes is
what you can do on it:
refuses with a "Chart subscription expired — renew in the Store" notice.
chart (unless another licensed chart also covers that water). The refusal
offers Renew directly.
routing engine keep working.
Renew from the [Charts button](#chart-downloads) (fastest), from the
refusal prompt, or in the Store.
Offline tiles
Open the Cache sheet from the chart's action menu to download a tile
pack for the area you are sailing. With a region installed from the
Store, the area becomes fully offline-capable.
If something goes wrong
or installed the matching region. See Store.
for your draft; nudge the point into deeper water and try again.
endpoints in deeper water.