Currents & Tides Overlays

Layer ocean currents, tidal currents and water heights onto the chart from several complementary sources that kick in depending on where you sail, so you can anticipate set, drift and tide rips.

Where to find it

Map › floating Overlays button (layers icon, top-left of the map) › Currents tab (wave icon).

Hierarchy

Overlays (floating panel)
└── Currents (tab — wave icon)
    ├── Current Forecast      (real-time ocean current forecast)
    ├── Currents              (major ocean currents — climatology)
    ├── Tides                 (tidal currents NOAA + UKHO)
    ├── SHOM Currents         (French tidal currents)
    ├── Ocean Currents        (global surface currents CMEMS)
    ├── Tidal C2D             (SHOM 2D tidal currents, heatmap + arrows)
    ├── Tide Heights          (global water heights FES2022)
    ├── Wind vs Current       (tide-rip detection)
    └── Strait of Gibraltar   (dedicated high-density overlay)

Opening the panel and the Currents tab

  1. On the map, click the Overlays button in the top-left corner to expand the panel.
  2. In the tab row, click the Currents tab (wave icon).
  3. Toggle each overlay on or off by clicking its button; an active overlay shows in colour, and a badge counts how many overlays are active in the tab.
  4. When an active overlay has a caveat, an amber hint line (ⓘ icon) appears just below it, spelling out the requirement (zoom, server, connection).

Source cascade — which one to use

Several overlays provide a "current": they do not cover the same areas, nor rely on the same data. In plain terms:

Overlay Current type Coverage Source Requirement
Current Forecast Ocean, real-time (speed + direction, includes tides and waves) Global Open-Meteo marine Real-time forecast or GRIB (disabled in climatological mode)
Currents Major permanent currents (Gulf Stream, etc.) Global Built-in climatology None
Tides Hourly tidal currents United States + United Kingdom NOAA + UKHO UKHO API key in Config for the UK
SHOM Currents French tidal currents Atlantic & Channel SHOM ncWMS Internet connection
Ocean Currents Global surface currents Global Copernicus CMEMS Internet connection
Tidal C2D High-resolution 2D tidal currents French Channel / Atlantic SHOM C2D Zoom ≥ 9
Tide Heights Water height (not a current) Global FES2022 (CNES/AVISO) Local PyFES server
Strait of Gibraltar High-density currents + tide races Strait of Gibraltar SHOM / FES2022 Map centred on the strait

Practical logic: - For an offshore passage, start with Current Forecast (captures the real dynamics) or with Currents in long-range climatological mode. - Near the French coast (Channel, Atlantic), SHOM Currents then Tidal C2D (zoom in) give the best tidal detail. - In the United States and United Kingdom, use Tides. - For a consistent worldwide view of surface currents, use Ocean Currents (CMEMS).

Current Forecast

What it's for: display ocean currents in real time — speed and direction — for the current forecast slot, factoring in the general current, tides and wave effects.

How to use it: 1. Open the Currents tab. 2. Click Current Forecast (the button turns cyan). 3. Current arrows appear over the visible area and follow the forecast hour selected on the map. 4. Click again to hide the overlay.

Options & settings:

Element Effect
Current Forecast button Toggles the real-time ocean current display.

Tips & limits: - This is a real-time overlay: unavailable in climatological mode (departure planned more than 7 days out). The button is then greyed out with the message "Unavailable in climatological mode". It needs a real-time forecast or a loaded GRIB file. - Open-Meteo marine data combining the Eulerian current, tides and waves — ideal for estimating set along the route.

Currents

What it's for: visualise the major permanent ocean currents and their direction (Gulf Stream, Canary Current, Equatorial Current, etc.), from climatology.

How to use it: 1. Open the Currents tab. 2. Click Currents (the button turns orange). 3. The major currents appear on the chart with their flow direction. 4. Click again to hide the overlay.

Options & settings:

Element Effect
Currents button Shows the major climatological ocean currents and their direction.

Tips & limits: - A climatological source: average values, not a forecast for the day. Always available, even offline and in long-range planning. - Perfect for shaping a passage strategy weeks ahead (for example, to ride the Gulf Stream on a return transat).

Tides

What it's for: display hourly tidal currents over areas covered by the US (NOAA) and UK (UKHO) hydrographic services.

How to use it: 1. Open the Currents tab. 2. Click Tides (the button turns dark cyan). 3. Tidal current arrows appear over the covered US and UK areas. 4. Click again to hide the overlay.

Options & settings:

Element Effect
Tides button Toggles NOAA (US) and UKHO (UK) tidal currents.

Tips & limits: - The hint reminds you of the source: NOAA (US) + UKHO (UK, requires API key in Config). - UK coverage requires a UKHO API key entered in the Config tab; without a key, only NOAA (United States) areas show. - For French tidal currents, prefer SHOM Currents or Tidal C2D.

SHOM Currents

What it's for: display French tidal currents from SHOM, over the Atlantic and the Channel.

How to use it: 1. Open the Currents tab. 2. Click SHOM Currents (the button turns indigo). 3. Tidal currents appear over the Atlantic seaboard and the Channel. 4. Click again to hide the overlay.

Options & settings:

Element Effect
SHOM Currents button Shows French tidal currents (SHOM ncWMS service).

Tips & limits: - Coverage limited to the Atlantic and the Channel (SHOM ncWMS service). - Requires an internet connection to query the service. - For high-resolution detail with a speed heatmap, switch to Tidal C2D by zooming in.

Ocean Currents

What it's for: display surface currents at global scale, for a consistent view across any ocean.

How to use it: 1. Open the Currents tab. 2. Click Ocean Currents (the button turns emerald green). 3. Global surface currents appear on the chart. 4. Click again to hide the overlay.

Options & settings:

Element Effect
Ocean Currents button Shows global surface currents (Copernicus CMEMS).

Tips & limits: - Copernicus CMEMS source: worldwide coverage, ideal for comparing currents across oceans on a long route. - Requires an internet connection.

Tidal C2D

What it's for: display SHOM 2D tidal currents in high resolution as a maximum-speed heatmap, complemented by hourly current arrows (French Channel / Atlantic).

How to use it: 1. Open the Currents tab. 2. Click Tidal C2D (the button turns blue). 3. Zoom in to at least level 9: the heatmap and arrows only appear from that level. 4. Click again to hide the overlay.

Options & settings:

Element Effect
Tidal C2D button Shows the SHOM max-speed heatmap and hourly current arrows.

Tips & limits: - Zoom ≥ 9 required: an amber hint line reminds you as soon as you turn it on. - Computed for tidal coefficients of 45 to 95 (Channel / Atlantic). - The heatmap highlights strong-current zones (passages, races); the hourly arrows help you time your transit window.

Tide Heights

What it's for: display water heights (not a current) at global scale, computed by the FES2022 harmonic model, with hour-by-hour navigation and a tide curve.

How to use it: 1. Open the Currents tab. 2. Click Tide Heights (the button turns dark teal). 3. Zoom in (level 5 and up) to reveal the tide grid. 4. Click again to hide the overlay.

Options & settings:

Element Effect
Tide Heights button Toggles the global FES2022 water-height grid.
Hourly navigation Previous hour / Current time / Next hour to step through the tide.
Low / High markers Indicate low water (Low) and high water (High).
Tide curve (24h) Plots the water-height evolution over 24 hours.

Tips & limits: - Requires the local PyFES server: without it, the overlay shows "Tide server offline". Available in desktop app mode. - FES2022 model (34 harmonic components, CNES/AVISO): worldwide coverage. - If nothing shows, check the zoom level (5+) and that the tide server is online.

Wind vs Current

What it's for: spot dangerous tide-rip zones — where wind above 15 knots opposes a current above 1 knot, producing a steep, breaking sea ("wind against current").

How to use it: 1. Open the Currents tab. 2. Click Wind vs Current (the button turns red). 3. Tide-rip risk zones appear over the visible grid. 4. Click again to hide the overlay.

Options & settings:

Element Effect
Wind vs Current button Toggles wind-against-current (breaking-sea) detection.

Tips & limits: - Cross-references Open-Meteo wind and marine current on a grid covering the visible area. - Trigger criterion: wind > 15 knots opposing a current > 1 knot. - Watch this especially in passages, river mouths and races: flagged zones signal a hard, unpleasant sea, potentially dangerous for a small boat.

Strait of Gibraltar

What it's for: a dedicated overlay for the Gibraltar passage — high-density currents, tide races (Camarinal, Tarifa SE, Algeciras, Europa Point) and the optimal transit window computed from the Tarifa tide.

How to use it: 1. Open the Currents tab. 2. Click Strait of Gibraltar (the button turns orange). The map automatically recentres on the strait. 3. Review the high-density currents and the identified tide races; find the optimal transit window. 4. Click again to hide the overlay.

Options & settings:

Element Effect
Strait of Gibraltar button Shows high-density currents, tide races and the optimal transit window.

Tips & limits: - The overlay is active only when the map covers the strait: turning it on recentres the view on Gibraltar. - The transit window and Tarifa HW/LW times are computed via FES2022 (desktop app mode). - Built to optimise the east-to-west or west-to-east passage by riding the favourable current and avoiding the Camarinal and Tarifa races.

See also