To get 40k coins in Starlit Isles , the fastest legit route is usually cargo trading and route repetition, not random grinding. A guide found in public results says a full round trip can yield about 225k coins with a well- set-up junk ship, which works out to roughly 5,000 coins per cargo slot.

Fast coin route

  1. Start with the biggest cargo ship you can use.
  2. Buy a full load of the first cheap cargo.
  3. Sell at the first profit port.
  4. Mine or gather the higher-tier materials needed for the next cargo tier.
  5. Keep moving between ports and buy the next more valuable cargo each leg.
  6. Repeat the loop instead of staying in one place.

What the guide suggests

  • Cargo size matters a lot; more storage means more profit per trip.
  • Certain ores respawn on timers, so farming them once and then reusing the route saves time.
  • The final destination changes depending on the best selling price, so check the merchant before each run.

How long it takes

The same guide says the loop can take around 60 minutes depending on wind conditions. That means 40k coins is often doable in one or a few efficient runs, especially once your ship and route are optimized.

Safer beginner option

If you are new, the simpler money methods in Starlit Isles are freight by sea, freight by train, and trawling, with cargo trading being the main route described in a money guide. For a beginner, doing shorter sea runs first is usually easier than pushing the full advanced loop right away.

Practical target

A simple way to think about it is:

  • If you earn about 5,000 coins per cargo slot per full run, then 40k coins is around 8 cargo-slot’s worth of profit.
  • With a decent ship and repeated runs, that is not a huge amount by late-game standards.

TL;DR

Use cargo trading, maximize ship storage, and repeat the most profitable port- to-port route. That is the most efficient legit way to reach 40k coins based on the public guide results I found.