#marine

Marine and surf forecasts as an API, powered by Open-Meteo — clean JSON, no key. Get the current sea state and the hourly and daily wave forecast for any coastline by latitude/longitude or simply by place name: significant wave height, period and direction, plus the swell and wind-wave components broken out separately, and daily maxima and dominant directions. A built-in geocoding helper turns a place name into coordinates. Forecasts run up to ten days ahead. Live forecast data straight from Open-Meteo's marine model. Ideal for surf-report apps, sailing and boating tools, coastal and marine-operations dashboards and beach widgets. 4 data endpoints. Authenticated with an x-oanor-key; fair-use rate limits per plan.

api.oanor.com/marine-api

Sea-horizon and visibility maths as an API, computed locally and deterministically — the distance-to-horizon, geographic-range and dip numbers a mariner, coastal navigator or marine app works sightings with. The horizon endpoint gives the distance to the sea horizon ≈ 1.169·√(height of eye in feet) nautical miles, including the standard atmospheric refraction that bends the line of sight a little past the geometric edge — at 9 ft of eye height the horizon is about 3.5 nm off — together with the dip, how far below true horizontal that watery edge lies (≈ 0.97′·√h), the correction subtracted from a sextant altitude shot to the sea horizon. The geographic-range endpoint gives how far off a light or landmark first peeps over the horizon = the sum of two horizon distances, your own plus the object's: 1.169·(√h_eye + √h_object), so a 100 ft lighthouse from a 9 ft cockpit lifts above the sea at about 15 nm — purely geometric, before the light's own luminous range and the visibility. The object-height endpoint inverts it: how tall a tower, light or headland must stand to break the horizon at a target range, or how close you must be before a known landmark appears. Everything is computed locally and deterministically, so it is instant and private. Ideal for marine-navigation and chartplotter apps, coastal-pilotage and lighthouse tools, and sailing utilities. Pure local computation — no key, no third-party service, instant. Geometric/refraction model. 3 compute endpoints. For great-circle distance use a geo-distance API; for set & drift a set-and-drift API.

api.oanor.com/horizon-api

Current-sailing (set and drift) navigation maths as an API, computed locally and deterministically — the course-over-ground, course-to-steer and current numbers a mariner, navigator or marine app plots a passage with. The course-made-good endpoint adds the boat's velocity through the water to the current vector to give the real track: the course over ground (COG) and speed over ground (SOG), with the drift angle the current pushes you off your nose — steering 090° through the water at 10 knots with a 2-knot current setting north comes out around 079° over the ground at 10.2 knots. The course-to-steer endpoint solves the other way: the heading to steer to make good a desired ground track, steering up-current to cancel the across-track set (sin(H−T) = −drift·sin(set−track) ÷ speed), and the resulting SOG — usually slower into a current, faster with it astern, and impossible if the current across the track beats your speed. The current endpoint finds the set and drift from the offset between a dead-reckoning position and an observed fix: the set is the bearing DR-to-fix and the drift is that distance ÷ the elapsed time, ready to carry forward. Everything is computed locally and deterministically, so it is instant and private. Ideal for marine-navigation and chartplotter apps, sailing and boating tools, and maritime-training utilities. Pure local computation — no key, no third-party service, instant. Degrees true. 3 compute endpoints. For great-circle distance use a geo-distance API; for tide times a tides API.

api.oanor.com/setanddrift-api

Seawater oceanography maths as an API, computed locally and deterministically from the standard equations — the density, freezing-point and chlorinity numbers an oceanographer, marine scientist or aquarist works with. The density endpoint gives the seawater density and σt from salinity and temperature using the full UNESCO EOS-80 one-atmosphere equation of state — it reproduces the official check value of 1027.675 kg/m³ at 35 PSU and 5 °C exactly — around 1,025 kg/m³, rising with salinity and falling with temperature, the two drivers of the ocean's density-driven circulation where cold salty water sinks. The freezing-point endpoint gives the freezing point from salinity (Millero): about −1.9 °C at the ocean's typical 35 ppt, and because salt also pushes the temperature of maximum density below freezing, seawater keeps overturning and cooling all the way down instead of stratifying like a freshwater lake — why the open ocean rarely freezes outside the polar seas. The chlorinity endpoint converts between salinity and chlorinity through the Knudsen relation S = 1.80655 × Cl, the classic titration measure that the constant major-ion proportions of seawater make reliable. Everything is computed locally and deterministically, so it is instant and private. Ideal for oceanography and marine-science tools, ocean-model and sensor pipelines, aquarium and aquaculture apps, and environmental dashboards. Pure local computation — no key, no third-party service, instant. Surface (atmospheric-pressure) forms. 3 compute endpoints. For the speed of sound in seawater use a sonar API; for general colligative properties a colligative-properties API.

api.oanor.com/seawater-api

Underwater-sound and sonar maths as an API, computed locally and deterministically — the speed, absorption and ranging numbers a marine engineer, sonar developer or oceanographer works with. The sound-speed endpoint gives the speed of sound in seawater from the Mackenzie nine-term equation: about 1,500 m/s — far faster than in air — rising with temperature, salinity and depth, so a profile of 25 °C, 35 ppt at 1,000 m gives 1,550.7 m/s. Because the speed varies with depth, sound rays bend and form the SOFAR channel that carries whale song and signals across whole oceans. The absorption endpoint gives Thorp's sound-absorption coefficient in dB per km against frequency, with the loss over a path: seawater swallows high frequencies fast, which is why long-range sonar and whale calls are low-pitched while high-frequency sonar gives sharp images only at short range. The echo-range endpoint turns an echo sounder's or sonar's two-way travel time into the range or depth — distance = sound speed × time ÷ 2 — so a one-second round trip at 1,500 m/s is a target 750 m away, its accuracy resting on the assumed sound speed. Everything is computed locally and deterministically, so it is instant and private. Ideal for sonar and hydrophone tools, marine-survey and bathymetry apps, ocean-acoustics research, and AUV/ROV navigation utilities. Pure local computation — no key, no third-party service, instant. Standard-equation estimates over their valid ranges. 3 compute endpoints. For the speed of sound in air and Mach use a Mach-number API; for decibels a sound-level API.

api.oanor.com/sonar-api

Ship initial-stability maths as an API, computed locally and deterministically — the metacentric-height, righting-moment and rolling-period numbers a naval architect, ship officer or marine-surveyor judges a vessel by. The metacentric-height endpoint gives GM = KM − KG, the single most important stability figure: the height of the metacentre (set by the hull form and draught) above the centre of gravity (set by how the ship is loaded), with a classification from a dangerous negative GM, through tender and comfortable, to a stiff GM that rolls violently — naval architects aim for the middle, because too little is unsafe and too much is hard on cargo and crew. The righting-moment endpoint gives the small-angle righting arm GZ ≈ GM · sin(heel) and the righting moment (GZ × displacement) that pushes the ship back upright, valid up to roughly 7–10° before the true GZ curve bends away. The roll-period endpoint gives the natural transverse rolling period T = 2π·k / √(g·GM) from the GM and beam — the same relation sailors run in reverse as the rolling-period test, where a suddenly longer roll warns that GM has dropped. Everything is computed locally and deterministically, so it is instant and private. Ideal for naval-architecture and ship-design tools, marine-surveyor and loading-software utilities, maritime-training apps and stability dashboards. Pure local computation — no key, no third-party service, instant. Initial-stability estimates — use full KN cross-curves for large angles. 3 compute endpoints. For hull speed and design ratios use a sailing API.

api.oanor.com/shipstability-api

Boat-propeller maths as an API, computed locally and deterministically — the slip, RPM and pitch numbers that decide whether a boat hits its numbers or labours. The slip endpoint gives propeller slip from the pitch, the prop RPM and the actual boat speed: theoretical speed = pitch × prop RPM ÷ 1215, and slip = (theoretical − actual) ÷ theoretical — a 19-inch prop at 2000 RPM should make 31 knots in theory, so a real 26.6 knots is about 15 % slip, normal for a clean planing boat. The prop-rpm endpoint gives the propeller RPM from the engine RPM and the gear (reduction) ratio — a 2:1 gearbox spins the prop at half engine speed — and, with a pitch, the theoretical no-slip speed at that RPM. The pitch endpoint gives the pitch needed to reach a target speed at a prop RPM and expected slip, pitch = target × 1215 ÷ (prop RPM × (1 − slip)), so you can prop the boat to let the engine reach the top of its wide-open-throttle range instead of lugging. Everything is computed locally and deterministically, so it is instant and private. Ideal for boating and marine apps, repower and prop-shop tools, performance calculators, and seamanship study aids. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 compute endpoints. Estimates — hull, load and bottom condition shift real slip.

api.oanor.com/propeller-api

Boat-anchoring maths as an API, computed locally and deterministically — the scope, swing and load numbers a sailor or boater sets the hook by. The scope endpoint gives the rode to let out: scope = rode ÷ the vertical from the seabed to the bow roller (water depth + bow height), measured at high tide, so anchoring in 20 feet with a 4-foot bow at the classic 7:1 means paying out 168 feet of rode — let out more in a blow, and never less than 5:1 on all chain. The swing endpoint gives the circle the boat swings on: radius = the horizontal reach of the rode (√(rode² − vertical²)) plus the boat length, so that 168-foot rode on a 30-foot boat sweeps a 196-foot radius — the room you must leave every other boat, which swings too. The load endpoint gives the wind load the ground tackle has to hold, 0.00256 × drag coefficient × frontal windage area × wind speed², which quadruples every time the wind doubles — 50 square feet of windage takes 138 lb at 30 mph but 553 lb at 60. Everything is computed locally and deterministically, so it is instant and private. Ideal for sailing and boating apps, anchoring and cruising tools, ground-tackle sizing calculators, and seamanship study aids. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 compute endpoints. Estimates — add current, waves and a safety margin.

api.oanor.com/anchor-api

Sailing and naval-architecture maths as an API, computed locally and deterministically — the hull-speed and design-ratio numbers a sailor, boat-shopper or yacht designer sizes a boat with. The hullspeed endpoint gives the theoretical displacement speed limit from the waterline: hull speed = 1.34 × √LWL (feet) in knots, so a 25-foot waterline tops out around 6.7 knots (7.7 mph, 12.4 km/h) — with a tunable coefficient up to about 1.5 for light, easily-driven hulls, since planing boats leave the formula behind entirely. The ratios endpoint computes the two classic performance numbers: the Sail Area/Displacement ratio, SA/D = sail area ÷ (displaced volume in ft³)^⅔ using displaced volume = displacement ÷ 64 lb/ft³ for seawater — around 16–18 is a typical cruiser and 20-plus is sporty — and the Displacement/Length ratio, DLR = (displacement in long tons) ÷ (0.01 × LWL)³, where under 200 is light and over 300 is heavy, each returned with a class label. The ballast endpoint gives the ballast ratio = ballast ÷ displacement × 100, a rough proxy for stiffness and sail-carrying power that most cruisers hit near 35–45 %. Everything is computed locally and deterministically, so it is instant and private. Ideal for sailing, boating, marine, yacht-brokerage and boat-design app developers, boat-comparison and rig-sizing tools, and naval-architecture calculators. Pure local computation — no key, no third-party service, instant. Imperial units. Live, nothing stored. 3 compute endpoints. Design-ratio estimates, not a velocity prediction program.

api.oanor.com/sailing-api

The Beaufort wind scale as an API, computed locally and deterministically. The classify endpoint turns a measured wind speed — in metres per second, kilometres per hour, knots, miles per hour or feet per second — into its Beaufort force (0 calm to 12 hurricane), with the descriptive name (light breeze, gale, storm …), the corresponding sea state and the mean open-sea wave height, plus the speed expressed in every unit. The force endpoint looks up a Beaufort number and returns its wind-speed range in all units, its description, sea condition and wave height. The convert endpoint converts a wind speed across metres per second, kilometres per hour, knots, miles per hour and feet per second and reports the matching Beaufort force (1 knot = 0.514444 m/s). Speeds use the standard 10-metre reference height and wave heights are open-sea means. Everything is computed locally and deterministically, so it is instant and private. Ideal for sailing, marine, aviation, drone, weather and outdoor app developers, wind-warning and sea-state tools, and meteorology education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is the Beaufort wind scale; for the feels-like wind chill use a feels-like API and for live wind observations a weather data API.

api.oanor.com/beaufort-api

Archimedes buoyancy and flotation maths as an API, computed locally and deterministically. The buoyancy endpoint computes the buoyant force on a submerged or floating body, Fb = ρ_fluid·g·V_displaced — the upthrust equals the weight of the displaced fluid — from a displaced volume and a fluid (water, seawater, oil, mercury and more, or a custom density), and also gives the mass of displaced fluid; it solves the volume from a known force too. The float endpoint decides whether an object floats, sinks or is neutrally buoyant by comparing its density (given directly, from a built-in material, or as mass divided by volume) with the fluid density, and for a floating object returns the fraction submerged f = ρ_object/ρ_fluid (so 90 % of an iceberg sits below the waterline), or for a sinking object its apparent (underwater) weight. The payload endpoint sizes flotation: the displaced volume needed to float a given load, V = W/(ρ_fluid·g), or the maximum extra payload a floating body of a given volume and density can carry before it submerges, Wmax = (ρ_fluid − ρ_body)·V·g. Everything is computed locally and deterministically, so it is instant and private. Ideal for naval-architecture and marine tools, diving, ROV and ballast apps, raft and pontoon design, and physics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is buoyancy and flotation; for pressure at depth and hydrostatic force on a wall use a hydrostatics API.

api.oanor.com/buoyancy-api

Live marine weather and ocean conditions from NOAA's National Data Buoy Center (NDBC). The station catalogue (1,930 moored buoys and coastal stations worldwide) is searchable by name, type or coordinate; the live endpoint returns the latest observation for any station: significant wave height, wave period and direction, water and air temperature, wind speed/gust/direction, atmospheric pressure and more. Find the nearest buoys to any lat/lon. Ideal for surfing & sailing apps, marine operations, coastal monitoring and oceanography.

api.oanor.com/buoys-api

High and low tide predictions for thousands of US coastal stations, powered by NOAA CO-OPS. Search the station directory by state or name, pull full station metadata (coordinates and time zone), and get tide predictions as high/low events or an hourly height series for up to seven days, in feet or metres and against the datum of your choice (MLLW, MSL, MHHW and more). Delivered through a fast, reliable API with clear errors for invalid stations. Ideal for boating and sailing, fishing and surfing, ports and logistics, beach and tourism services and coastal planning.

api.oanor.com/tides-api

Real-time and forecast ocean conditions for any coastal or open-water location. Get the current sea-surface temperature (in °C and °F) together with a wave snapshot — height, direction, period, swell and wind-wave — pull an hourly series of temperature and waves, or a daily forecast with sea-temperature min/avg/max and wave aggregates. Global ocean coverage sourced from Open-Meteo’s Marine model, delivered through a fast, reliable API; inland coordinates return a clear not-found so you always know you have ocean data. Ideal for surf and sailing apps, fishing and diving, beach and tourism services, shipping and coastal or climate monitoring.

api.oanor.com/seatemp-api

Real-time weather: current conditions, multi-day forecast, historical weather, marine/wave forecast, astronomy (sun/UV), air quality, geocoding and timezone.

api.oanor.com/weather-api