Escuela Náutica Altair
The Skipper App
Use it before you sail and while you sail.
See everythingFree · no sign-up · an aid, it does not replace official charts or the radio
Free skipper app: storm alerts, weather radar, live NAVTEX, COLREGs, buoyage, pre-departure checklist and radio
Everything in the app
Storms · radar and alerts
Loading the radar…
How does it work, and how far can I trust it?
Radar: the European composite from EUMETNET (OPERA), about 180 radars in 27 countries, every 5 minutes. It reaches some 100-150 miles offshore: further out there is no radar.
Lightning: the European weather satellite MTG sees it over Europe, Africa and the Atlantic, open sea included. A thunderstorm with lightning is the most dangerous kind: strong gusts, squalls and sudden wind shifts.
The alert: every 5 minutes the app looks for strong cells (40 dBZ or more) and lightning clusters, measures how far the rain has moved in the last quarter of an hour and works out how close they will pass to you, and when. It is the same as the CPA of AIS ships.
Limits: a thunderstorm is born, grows and dies within 30-60 minutes, and it can change direction. Trust the alert for the next hour, not for the afternoon. Data arrive 5-15 minutes late. It is an aid: it does not replace official warnings or looking at the sky.
Alert me on my phone: you get a notification even with the app closed, for the last position your phone had with the app open (forgotten after 24 h). On iPhone, first add the app to your home screen.
Radar © EUMETNET OPERA (CC BY 4.0) · lightning © EUMETSAT (MTG Lightning Imager).
Waves now
The forecast at your position, in any sea, and real measurements from the Spanish Puertos del Estado buoys.
What does each figure mean?
Significant height (Hm0): the average of the highest third of the waves. It is the one in the forecast and the closest to what you estimate by eye.
Maximum wave (Hmax): the highest wave measured in that hour. Expect the odd one that big.
Period (Tp): seconds between waves. Short (under 6 s) is wind sea, choppy and uncomfortable; long (over 9 s) is swell coming from far away.
Direction: where the waves come from. Sea state: Douglas scale from the significant height.
Puertos del Estado buoys (Spain)
Loading the buoys…
Data: Puertos del Estado (coastal and deep-water networks). Tap a buoy to see it on top. Forecast: Open-Meteo (CC BY 4.0).
COLREGs · who gives way
Hierarchy (rule 18)
From most to least priority. Each one keeps out of the way of those above it:
- Not under command
- Restricted in her ability to manoeuvre
- Constrained by her draught
- Engaged in fishing (with gear that restricts manoeuvrability)
- Sailing vessel
- Power-driven vessel
The overtaking vessel always gives way, whatever she is (rule 13).
Crossing (rule 15)
She is on your starboard side (you see her red light): you give way. Turn to starboard and pass astern of her, never ahead.
Head-on (rule 14)
Bow to bow: both turn to starboard and pass port to port.
Overtaking (rule 13)
If you come up from more than 22.5° abaft her beam, you are overtaking and you keep clear, sail or power, until you are well past.
Sailing vessels on opposite tacks (rule 12)
The one with the wind on the port side (on port tack) gives way.
Sailing vessels on the same tack (rule 12)
The windward boat gives way, the one further “up” towards the wind.
you · the other · what you must do
Always
- Risk of collision (rule 7): if the other vessel’s bearing does not change and the range closes, you will collide.
- The give-way vessel: early, clear and substantial action (rule 8). The stand-on vessel: keeps course and speed, but acts if she sees the other is not doing so (rule 17).
- Narrow channels (rule 9): vessels under 20 m and sailing vessels must not impede those that can only navigate within the channel. Keep to your starboard side.
- Proper lookout and safe speed at all times (rules 5 and 6).
Navigation lights of a power-driven vessel
White masthead light forward, green to starboard, red to port and white sternlight aft. A sailing vessel under sail carries the same without the masthead light (or a tricolour at the masthead if under 20 m). A power vessel under 12 m may show an all-round white light instead of masthead and sternlight.
Special lights and day shapes
Night lights are all-round and in a vertical line, in addition to the navigation lights if the vessel is making way. More on navigation lights.
Sound signals (rules 34 and 35)
| • (1 short) | I am altering to starboard |
| •• (2 short) | I am altering to port |
| ••• (3 short) | I am going astern |
| ••••• (5 or more) | I do not understand your intentions / doubt |
| — (1 long) | Approaching a bend |
| Fog, power vessel making way | One long, at intervals of not more than 2 minutes |
| Fog, power vessel stopped | Two long |
| Fog, sailing, fishing, NUC… | One long and two short |
The full rules, with a simulator: who has right of way.
Buoyage
Region A: Europe, Africa, Asia (except Japan, Korea and the Philippines) and Oceania. Lateral marks “entering harbour”.
Region B: the Americas, Japan, Korea and the Philippines. Lateral marks are reversed: red to starboard when entering (“red right returning”). Lateral marks “entering harbour”.
Port-hand lateral
Red, can-shaped. Topmark: red can. Red light.
Entering harbour, leave it to your port side (on your left).
Starboard-hand lateral
Green, conical. Topmark: green cone point up. Green light.
Entering harbour, leave it to your starboard side (on your right).
Port-hand lateral
Green, can-shaped. Topmark: green can. Green light.
Entering harbour, leave it to your port side (on your left).
Starboard-hand lateral
Red, conical. Topmark: red cone point up. Red light.
Entering harbour, leave it to your starboard side (on your right).
North cardinal
Black over yellow. Two cones pointing up. Continuous white quick light: VQ or Q.
The danger is to the south: pass to its north.
East cardinal
Black, yellow, black. Cones base to base (points outwards). Light: 3 flashes, VQ(3) 5 s or Q(3) 10 s.
Pass to its east. Clock trick: 3 o’clock.
South cardinal
Yellow over black. Two cones pointing down. Light: 6 flashes + one long, VQ(6)+LFl 10 s or Q(6)+LFl 15 s.
Pass to its south. 6 o’clock.
West cardinal
Yellow, black, yellow. Cones point to point (hourglass). Light: 9 flashes, VQ(9) 10 s or Q(9) 15 s.
Pass to its west. 9 o’clock.
Isolated danger
Black with one or more horizontal red bands. Two black spheres. White light, group of 2 flashes: Fl(2).
Small danger with navigable water all round: keep clear.
Safe water
Red and white vertical stripes. One red sphere. White light: isophase, occulting, one long flash every 10 s or Morse “A”.
Mid-channel or landfall: safe water all round it.
Special mark
Yellow. Topmark: yellow X. Yellow light.
Special areas: swimming zones, outfalls, cables, military areas…
Emergency wreck marking
Blue and yellow vertical stripes. Yellow cross. Alternating blue and yellow light.
A new danger not yet on the charts (a wreck, for example).
With animations: cardinal marks and the buoyage system.
Let’s anchor
Chain: 3 to 5 times the depth (in 5 m, at least 20 m of chain). Let out more if it is blowing or if part of your rode is rope instead of chain.
- Choose the spot. Sand or mud bottom, sheltered from wind and sea, enough depth and away from boats already anchored. Never on seagrass such as posidonia: it is protected, usually forbidden, and the anchor does not hold.
- Prepare. Work out the chain, have the anchor ready and, if the bottom has rocks or ropes, rig a tripping line.
- Come in head to wind (or to the current), very slowly, and stop exactly where you want the anchor.
- Drop the anchor and pay out chain while going astern very slowly, without piling it on top of the anchor.
- Make fast and set it: a gentle pull astern on the engine so the anchor digs in.
- Check you are not dragging: take two transits ashore (or set the GPS anchor alarm) and check again a few minutes later and every time the wind shifts.
- Signals: by day a black ball forward; at night an all-round white light.
- To weigh anchor: motor slowly ahead while recovering chain (do not let the windlass pull the boat), and break the anchor out when the chain is up and down.
The tripping line
A line from the crown of the anchor to a small buoy on the surface. It shows where your anchor is (so nobody anchors on top) and, if it fouls a rock or another chain, you pull it out by the tripping line, the opposite way it went in.
Swinging
At anchor the boat swings around the anchor when the wind or current shifts. The radius of that circle is roughly the chain out plus your length. Leave room so your circle does not overlap your neighbours’: boats on rope swing more than boats on chain.
More: how much chain to let out, the trip line and sustainable anchoring.
Before sailing
Tick it off before casting off. It clears itself the next day.
- Weather forecast for the area, storms and warnings (Storms and NAVTEX tabs)
- Passage plan left with someone ashore: where you are going and when you will be back
- Fuel: a third to go, a third to come back and a third in reserve
- Engine: oil, belts and, once started, cooling water coming out of the exhaust
- Battery charged, isolator on and navigation lights working
- Boat and skipper papers and valid insurance on board
- Lifejackets for everyone, to hand, and a lifebuoy or throw line for man overboard
- Safety equipment for your sailing area: flares, first-aid kit, extinguisher, bailer
- VHF on, on channel 16, and phone charged in a waterproof pouch
- Bilge dry and bilge pump working
- Crew briefed: where the lifejackets are, how to stop the engine and what to do if someone falls overboard
- Fenders, lines and anchor ready
Mandatory papers and equipment depend on your boat, its flag and your sailing area.
Radio · emergencies
1. DSC distress alert
Lift the red cover and hold down DISTRESS for a few seconds, until the radio confirms it has been sent (3 or 5 s depending on the model). If there is time, choose the nature of distress first. It sends your position and MMSI to all stations.
2. MAYDAY by voice · channel 16, high power
- MAYDAY, MAYDAY, MAYDAY
- THIS IS [boat name ×3], [MMSI or call sign]
- MAYDAY [boat name], [MMSI]
- Position (latitude and longitude, or bearing and distance from a known point) · see mine
- What is happening: taking water, fire, man overboard…
- What help you need
- Persons on board and any other useful information
- OVER
Urgency and safety
- PAN PAN (×3): urgency with no immediate danger to life (engine failure and drifting, an injured person…).
- SÉCURITÉ (×3): navigational or weather safety message.
Rescue phone number
Always first: channel 16 or the DSC alert, so the rescue centre and the boats around you hear you. Use the phone if you have no radio, or to talk calmly.
Channels
- Channel 16: distress, safety and calling. Then switch to the working channel you are given.
- Channel 70: DSC calls only, never voice.
- Marinas: the channel varies by country and harbour (in Spain, usually 9). Call the marina before entering to get a berth; check its website or the pilot book.
More on how to make a MAYDAY call.
Phonetic alphabet (International Code of Signals)
To spell out the boat’s name, the call sign or a word that is not understood. Example: BELA = Bravo Echo Lima Alfa.
- AAlfaAL-fah
- BBravoBRAH-voh
- CCharlieCHAR-lee
- DDeltaDELL-tah
- EEchoECK-oh
- FFoxtrotFOKS-trot
- GGolfGOLF
- HHotelhoh-TELL
- IIndiaIN-dee-ah
- JJuliettJEW-lee-ett
- KKiloKEY-loh
- LLimaLEE-mah
- MMikeMIKE
- NNovemberno-VEM-ber
- OOscarOSS-cah
- PPapapah-PAH
- QQuebeckeh-BECK
- RRomeoROW-me-oh
- SSierrasee-AIR-rah
- TTangoTANG-go
- UUniformYOU-nee-form
- VVictorVIK-tah
- WWhiskeyWISS-key
- XX-rayECKS-ray
- YYankeeYANG-key
- ZZuluZOO-loo
Numerals (International Code of Signals)
On the radio people normally say numbers digit by digit in their own language (“four one, two zero”). The International Code of Signals also has these words, designed to be understood in any language:
- 0Nadazero
- 1Unaone
- 2Bissotwo
- 3Terrathree
- 4Kartefour
- 5Pantafive
- 6Soxisix
- 7Settaseven
- 8Oktoeight
- 9Novenine
Chart and position
Tap GPS and allow location.
· Drag A and B, or tap the chart to move B. True course.
Tap a point on the chart and press “Save waypoint”. They are stored on this phone.
Press record when you leave: the purple line is today’s track and tomorrow the chart starts clean. Each day is saved on this phone. It only records while the app is open and the screen is on.
Previous days
No tracks from other days yet.
- Tap a point on the chart: course, distance and time from where you are. You can save it as a waypoint.
- Track: records your route for the day (purple line). Previous days stay saved on the phone: tap one to see it in blue or download it as GPX.
- No coverage: the chart keeps on the phone the areas you look at. Before you leave, browse your area with coverage at the zoom levels you will use and you will see it later with no signal. GPS always works.
- Radar: rain and storms over the last hour (▶ to animate). Outlines are the strong cells and the dashed line shows where they will go in the next hour.
- Seabed: seabed relief and depth contours. In Europe from EMODnet, and tapping a point shows its approximate depth; elsewhere in the world, from GEBCO.
- Services: marinas, fuel docks, slipways, harbour masters, boatyards and chandlers from OpenStreetMap, in any country. Tap one to see course, distance and “Go here”. Some may be missing or out of date: confirm by radio or phone.
- Tap a ship (AIS): who she is, how far away and how close she will pass.
- The course is true and in a straight line: check you do not cross shoals or land, and for the compass correct for variation and deviation.
Sailing & pleasure Passenger Cargo & tankers Fishing Tug, pilot, SAR Other · a dot = stopped · ▲ you
Not an official chart: it does not replace official nautical charts, your chartplotter or a proper lookout. Without coverage you only see the areas you have already looked at with coverage. AIS ships arrive late and not all of them are there. EMODnet depths are averages over cells of about 115 m, and GEBCO is coarser still: they do not see shoals, rocks or wrecks. Map © OpenStreetMap · seamarks © OpenSeaMap · bathymetry © EMODnet (CC BY 4.0) and GEBCO · services © OpenStreetMap contributors (ODbL) · AIS: aisstream.io · radar © EUMETNET OPERA (CC BY 4.0) · lightning © EUMETSAT.
Points of sail
Press ▶ Play: the boat goes through every point of sail, from head to wind to a dead run, and on each one you see how the main and the jib are trimmed.
Loading the demo…
Cheat sheet
- Head to wind: the sails flap and do not drive (no-go zone).
- Close-hauled (≈ 30° off the wind): sails sheeted right in.
- Close reach (≈ 60°): a little more eased.
- Beam reach (≈ 90°): sails half out.
- Broad reach (≈ 120°, wind on the quarter): sails well eased.
- Running (≈ 180°): sails all the way out.
True and apparent wind
The wind you feel on board (apparent) is not the true wind: the wind created by your own speed is added to it. That is why it seems to blow harder close-hauled and less when running.
Loading the demo…
Learn it on the water on our sailing course.
Manoeuvring simulator: berthing alongside in a crosswind
Knots
Choose a knot and press ▶ Play: step by step, with the typical mistake for each one.
What for: A fixed loop that does not slip: to drop over a bollard or make a rescue loop.
Loading the demo…
What for: The first line ashore when you reach the quay, thrown from the boat.
Loading the demo…
What for: To make fast quickly to something round: stanchion, rail, bitt. For the fenders.
Loading the demo…
What for: To make a line fast on a cleat and be able to release it in one pull.
Loading the demo…
What for: To make fast to a ring on the quay or to the anchor shackle.
Loading the demo…
What for: To join two lines of the same size (and not to confuse it with the granny knot).
Loading the demo…
What for: To join two lines of different size or material.
Loading the demo…
What for: A stopper at the end of a line (sheets, halyards) so it cannot run out through a block or a fairlead.
Loading the demo…
Practise them on board on our sailing course.
Useful links
What a skipper checks before sailing.
- WindyWind, gusts and waves hour by hour, on a map.
- NavilyAnchorages and marinas with reviews and photos from other sailors.
- NoforeignlandCruisers’ community: anchorages, marinas and services added by sailors.
- VesselFinderAIS ships on a map of the whole world.
- Escuela Náutica AltairSailing courses, boat licence and sailing trips from Port Garraf, near Barcelona.
- Pre-purchase boat inspectionWe survey the boat you want to buy: osmosis, thickness, rigging, electrics and sea trial, with a written report to negotiate. From €550 up to 12 m.
- Boat repairElectronics, engine and refit at Port Garraf and around. Send us photos on WhatsApp: the quote is free.