Storms: 45 years of real hurricanes, typhoons and cyclones

Real storms on the game clock

The storms in PerpeNaval are not random. They are replayed from NOAA's IBTrACS record, the international archive of tropical cyclone tracks: 3,859 storms from 1980 to 2024 that reached at least tropical storm strength (34 knots), each with its position, maximum wind and the size of its gale and hurricane-force wind fields every six hours.

Game day 1 corresponds to 1 January 1980, and the record plays forward on the game clock. Because one game day lasts 25 real minutes, storms move at their real speed relative to ships: a hurricane that lasted a week in reality plays out over about three real hours. The 45-year record takes roughly 285 real days to play through, then loops.

The tracks are real but the names are the game's own. Each basin works through its own list of storm names in order through the season, so a famous storm's track appears under a different name.

Reading a storm on the chart

Each storm is drawn as an emblem coloured by its strength: green for a tropical storm, then yellow, amber, orange and red-orange for categories 1 to 4, and red for category 5. Around it are two rings: the gale ring, the area of tropical-storm-force winds (34 knots), and the core, the hurricane-force winds (64 knots). Behind it is its past track, and ahead a three-day forecast track in a widening cone.

Categories follow wind speed on the familiar scale, from category 1 at 64 knots to category 5 at 137 knots and above. A storm is a hurricane in the North Atlantic and eastern Pacific, a typhoon in the western Pacific, and a cyclone in the Indian Ocean and South Pacific.

The storm outlook

Nothing hits you by surprise. Every storm appears in the storm outlook a full real day before it forms, with its basin, timing, peak strength and lifetime. If it will pass near a port where one of your ships is docked or bound, you get an alert, and the Warnings box lists threatened ports, ships held by weather and closed ports.

Forecast: going around or waiting it out

The Advanced Weather Forecast is a Keel node available to every calling (it needs Radar first), and it is built into every tier 3 and larger hull. With a forecast, the planner checks the whole voyage against where each storm will be at every hour of it. If a storm's gale ring would cross her path, the planner compares two answers: a route around the storm, or a wait in port until the path is clear. It picks whichever is faster and says so on the receipt, with the hours of the hold or the extra kilometres of the detour. If every way through is blocked, the voyage is not sent.

Without a forecast, the receipt tells you plainly that the storms are yours to judge. The ship sails her planned route, and whatever she meets is settled when she lands.

What a storm costs at sea

A ship that meets weather pays in three ways, all settled on landing:

• Wear: a voyage through a gale ring wears the hull twice as fast, and through the core of a category 3 or stronger storm four times as fast. Below 70% condition a ship is 5% slower and thirstier until drydocked.
• Storm bill: crossing the core of a category 3 or stronger storm costs 4% of the voyage's pay per category, capped at 30% of the pay. Insurance pays it in full.
• Incident risk: the small chance of an incident on landing (a grounding, a fire, a flooded hold) doubles in a gale and is four times higher in a major storm's core.

For cruise ships, a storm hold or detour also costs passenger satisfaction, which Stabilizers soften.

What storms never do

Storms never sink, destroy or confiscate a ship. No ship in PerpeNaval is ever lost. The worst a storm can do is cost time, condition and a capped repair bill, and a forecast or insurance removes most of that.

Port closures and recovery

When a storm of category 1 or stronger passes over a port, so that the port lies well inside its gale ring, the port is closed: cargo charters into it, and cruise trips and lines that call there, drop off the boards until the storm moves on.

After the storm the port spends 4 + 2 × category game days recovering, so about 6 game days after a category 1 and 14 after a category 5. During recovery the sea responds:

• Relief cargo appears on the boards of the three nearest ports: relief supplies, building materials, bottled water or generators, paying 75% (category 1) up to 135% (category 5) above normal, with no tariff and 15 Elo on delivery.
• Food runs by fishers from the recovering port pay 30% more.
• Evacuation charters let a cruise ship docked in the closed port carry people to the nearest open port, at break-even fares and 40 Elo.
• Fuel, food and building work all head toward the port as the sea responds.

The Hurricane relief event on the calendar raises relief cargo by a further 30% for two days.

Storm seasons by basin

The seasons are the real ones. Counts are storms in the 1980–2024 record:

• North Atlantic (603 storms): June to November, peaking August to October. The Caribbean, the Gulf of Mexico and the US East Coast are most at risk.
• Eastern Pacific (774): late May to October, peaking in August, mostly off Mexico and Central America.
• Western Pacific (1,095): the busiest basin, with typhoons in every month and a peak from July to October, from the Philippines to Japan.
• North Indian Ocean (213): two seasons between the monsoons, around May and from October to December.
• South Indian Ocean (719): November to April, peaking in January, from off Western Australia to Madagascar and Mozambique.
• South Pacific (452): December to April, peaking in February, from Queensland to Fiji and beyond.

The Australian region (about 90°E to 160°E) is split between the South Indian and South Pacific basins, with about 500 storms. The South Atlantic has only three storms in 45 years, and the Mediterranean, the Black Sea and northern Europe are almost never touched.

Famous storms in the record

Because the tracks are real, some of the most notable storms of the past half century sail through the game, under other names. Among them:

• The 1991 Bangladesh cyclone came ashore in late April 1991 with one of the deadliest storm surges of the period.
• Hurricane Andrew (1992) struck southern Florida as a category 5 storm.
• Hurricane Mitch (1998) brought catastrophic flooding to Honduras and Nicaragua.
• Cyclone Catarina (2004) was the first hurricane-strength storm on record in the South Atlantic and made landfall in southern Brazil.
• Hurricane Katrina (2005) devastated New Orleans and the Gulf Coast.
• Cyclone Nargis (2008) swept into Myanmar's Irrawaddy delta.
• Typhoon Haiyan (2013) struck the central Philippines as one of the most intense tropical cyclones ever to make landfall.
• Hurricane Patricia (2015) off western Mexico set the record for the highest sustained winds measured in the Western Hemisphere.
• Hurricanes Harvey and Irma (2017) hit Texas and the northern Caribbean within weeks of each other.
• Cyclone Idai (2019) made landfall near Beira in Mozambique.
• Cyclone Freddy (2023) is the longest-lived storm in the record, active for about five weeks as it crossed the Indian Ocean from off Australia to Madagascar and Mozambique.

When one of these tracks comes round, the sea reacts as to any storm: ships hold or reroute, ports close, and relief work appears.

Sailing smart in storm season

• Buy Radar and the Advanced Weather Forecast early on any tier 1 or tier 2 hull that works storm-prone water. From tier 3 it comes built in.
• Check the storm outlook before sending a long voyage. Storms are announced a full real day ahead.
• Turn on insurance in the season: it pays storm bills and incidents in full for 2% of each voyage's pay.
• A recovering port is an opportunity. Relief cargo, food runs and fuel are all wanted there.
• Drydock after a stormy voyage. Worn hulls are slower, thirstier and more likely to suffer incidents.