1/x Insurance for ships is a complicated matter, and you've probably heard "P&I Club" being mentioned. What is a P&I club? A small🧵
2/x P&I Club stands for Protection & Indemnity Club.
"P" = protection (e.g. certain damage to your own ship).
"I" = indemnity (reimbursement) for third-party liabilities from operating the ship, like injuring crew, damaging cargo, or polluting the sea.
3/x So what is a P&I club? They started in 19th-century UK. Shipowners found regular commercial insurers too pricey, and those policies often ignored cargo damage or crew injuries from normal ship use. Owners were left paying huge claims out-of-pocket.
4/x Solution? They formed "hull clubs", mutual groups where shipowners insured each other. Everyone chipped in fees, shared the risks, and ditched expensive middlemen (commercial insurers). This mutual pooling cut costs and covered the gaps.
5/x Over time (as shipping grew, laws changed, liabilities exploded), these became today's P&I clubs. The core idea remained unchanged: shipowners pool risks together in non-profit mutuals. Members (shipowners) pay an annual "call", basically a premium/contribution.
6/x Calls are due February 20. Why that odd date? Old tradition from the Baltic Sea trade: February 20 was roughly when winter ice melted, ports reopened, and sailing ships resumed voyages. So it became the "start" of the maritime insurance year.
7/x A P&I club is run by (and for) the shipowners themselves, true mutual insurance. Strictly non-profit: no shareholders taking profits. If claims in a year exceed collected calls, members pay extra (supplementary call). If claims are low, discounts/returns are possible.
8/x What do P&I clubs cover? Third-party liabilities not in standard hull insurance: crew injury/death, passenger claims, cargo damage/loss, collision damage to other ships, oil spills/pollution cleanup, wreck removal, fines for customs violations, etc. Big stuff!
9/x Entry isn't automatic. Ships must be seaworthy, well-maintained, and classed by a society (like Lloyd's Register). Crews need proper training/certificates. Clubs often send surveyors to inspect vessels & operations before accepting (or to monitor existing members).
10/x Soon, single claims got too massive for one club (huge pollution disasters). So clubs pooled again: they formed the International Group (IG) of P&I Clubs, the 12 big ones covering +-90% of world tonnage.
12/x In the IG pool: Each club keeps the first $10M USD of any claim (after member's deductible). Anything from $10M to $100M is shared across all 12 clubs ($90M + $10M pool layer). Proportional to each club's tonnage share.
13/x Excess of US $30 million, the Pool is reinsured by the Group captive reinsurance vehicle, Hydra Insurance Company Limited. Hydra is a Bermuda-incorporated Segregated Accounts company in which each of the 12 Group Clubs has its own segregated account (or “cell”).
14/x This segregated cell fences assets and liabilities from those of the company or any of the other Club cells. Hydra covers the upper pool slice ($30M–$100M).
15/x Above $100M? It goes into a tall "tower" of commercial reinsurance: the Group Excess of Loss (GXL) program. For 2026/27, this provides up to $2.25B in three layers (Layer 1: $650M + $100M; Layer 2: $750M + $750M; Layer 3: $850M + $1.5B), bought globally.
16/x Beyond the GXL tower? There's a final "collective overspill" layer ($1B + the $2.35B ceiling) where clubs share any extreme shortfall. The whole setup spreads mega-risks, so no single owner or club goes bankrupt from one bad claim.
17/x Standard P&I policies do not cover war risks, including war, terrorism, piracy, strikes, and similar events. These risks are covered separately through war risk policies or add-ons, which are typically inexpensive, though premiums can soar in high-risk areas.
18/x War risk cover is often placed through specialist markets (e.g., London) or IG clubs' fixed-premium arms. It's reinsured heavily in a similar layered tower as the main P&I program (pool -> Hydra -> GXL excess layers).
19/x Why separate? War events are unpredictable & potentially massive (e.g., mine strikes, missile hits, blockades). Pooling them with everyday P&I liabilities could bankrupt clubs if a major conflict hits. So war risks are "non-poolable" or specially reinsured.
20/x Clubs issued 72-hour cancellation notices (standard clause) starting March 1–2. Effective midnight GMT March 5, 2026: War risk cover auto-terminated for Iranian waters, Persian/Arabian Gulf, Gulf of Oman, and adjacent areas.
21/x They are now cancelling the primary war risks coverage, specifically the first layer, purchased separately through specialist markets (often based in London_ or via club fixed-premium options. The coverage activates from the first dollar, up to the vessel value or $500M
22/x There is a secondary (excess) war risk coverage that attaches to the first layer (which is NOT cancelled), but if the 1st layer is cancelled, that means that the shipowners have a huge deductible for the value of the 1st layer.
23/x Anyway.. It's all very complicated, but I hope this gives you an idea of what it means when we talk about P&I clubs and War Risk Coverage
24/x And I'm fully aware that Hydra Insurance Company Limited sounds like something from a James Bond movie and that probably somewhere, there's an inactive volcano with a missile inside of it, ready to launch, and destroy the world
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1/x You've probably encountered these AI videos of ships dumping garbage in the sea. Not true, of course, but how is garbage regulated at sea? a small 🧵
2/x MARPOL, formally known as the International Convention for the Prevention of Pollution from Ships, is the primary international treaty established by the International Maritime Organization (IMO) to prevent marine pollution by vessels.
3/x MARPOL is divided into several annexes, each regulating a specific type of ship-generated pollutant:
Annex I: Oil Pollution
Annex II: Noxious Liquid Substances
Annex III: Harmful Substances in Packaged Form
Annex IV: Sewage
Annex V: Garbage
Annex VI: Air Pollution
1/x OK. This time, we’ll look at how we actually calculate a tide in practice. First, a quick recap. What we know so far:
a. Tides are caused by tidal forces from celestial bodies.
2/x b. The shape of continents, seabed, etc., makes every tide completely different and unique from place to place, just like a fingerprint.
c. Every movement of Moon and Sun (Moon’s rotation, Earth’s rotation, Moon’s orbit, Sun’s orbit, etc.) is a small part of the total tide.
3/x These individual influences are called harmonic constituents, and each one creates its own wave. d. We have to add all those waves together to get the final tidal curve.
1/x Back to fun stuff: I'm going to try to explain the tides. Where do they come from, and how do we calculate them? I might have to split it into several threads because it's actually a lot and can be complicated.
2/x The first topic is the origin of tides. Most people say that tides are caused by the Moon's gravity, which attracts water towards it. This is why we experience high water (HW) on the side of the Earth facing the Moon. Yay! Cool and all, but why then 2x HW per day...?
3/x Ah yes, there's another "bulge" of water on the other side of the Earth. Yeah, but how is that possible? Wouldn't that side also be attracted by the Moon? This shows that a Tidal Force causes tides. This Tidal Force is a consequence and derivative of gravity.
1/x I notice many people confusing "transit passage" and "innocent passage" regarding the Strait of Hormuz. There also appears to be uncertainty about what qualifies as an "international strait." Let's clarify the differences. 🧵
2/x Those two terms stem from UNCLOS 1958 and UNCLOS 1982. If you want a history of how UNCLOS came to be, check the link below:
3/x First, we need to look at the definition of an "international strait." UNCLOS58 - art16(4) defines this as "straits which are used for international navigation between one part of the high seas and another part of the high seas or the territorial sea of a foreign State"
1/x I guess I have to deal with the Bosphorus Strait and the Dardanelles and their status as well, so here goes: They're essential strategic waterways that links the Black Sea with the world’s oceans. The Bosphorus also separates Asian Türkiye or Anatolia from European Türkiye.
2/x After WW1, the Armistice of Mudros (October 30, 1918 ended hostilities between Ottoman Turkey and the Allies. The Mudros document's 25 articles gave the Allied Powers the right to use the Dardanelles and Istanbul Straits freely and occupy fortifications on their shores.
3/x The temporary ceasefire was transformed into a permanent plan to dismantle the Ottoman Empire. This resulted in the Treaty of Sèvres on August 10, 1920. Türkiye rejected this Treaty.
1/x The comparison between the Suez Canal and the Strait of Hormuz is crooked, as the Strait of Hormuz is defined in UNCLOS82 as an international strait with the right of "transit passage" (not "innocent passage", that's UNCLOS58). But what about Suez? A small🧵
2/x The big difference is, of course, that the Canal is man-made and not a natural strait. It is also located entirely within Egyptian territory. It is fully subject to Egyptian sovereignty and jurisdiction, just like any other part of Egyptian land or inland waters.
3/x The Suez Canal was built by Ferdinand de Lesseps. He secured a concession from Egypt’s Khedive (autonomous tributary state of the Ottoman Empire) in 1854 and formed the Suez Canal Company in 1858. Construction began in 1859, and the canal opened in November 1869.