The charter packing question has one governing fact: your suitcase has to fit in a cabin locker, and the locker was designed by someone who assumed you would bring less. Soft duffels that fold flat beat rigid wheelie cases every time — hard shells that don't fit get walked to the lazarette or live on your bed all week. Pack into two bags: one of clothes that vanishes into a drawer, one of everything else. The week itself needs less than any land trip of the same length: you will live in swimwear and dry off in the sun.
This is a service guide to packing for a crewed charter week in warm seasons; if your broker or the yacht's preference pack says otherwise, the yacht wins.
The list that works
Swimwear, three sets — one is always wet and one is always drying. Cover-ups or light shirts for the deck between swims. Shorts and trousers in roughly the ratio you actually live in. Two evening outfits per week at most, because yachts dress down even when they dress up; one of them should survive a breeze on the aft deck. One genuinely warm layer — the wind at anchor after sunset is the most under-packed item in chartering — plus a light rain shell for the passage day that decides to be weather. Underwear for half the week plus laundry tolerance, a hat that stays on in a breeze, polarised sunglasses that float or a retainer for the pair that doesn't.
Feet, specifically
Two pairs, total. Deck shoes or trainers with light, non-marking soles — dark soles leave prints on white decks, and the deckhand notices before you do — and one pair of evening shoes that can also walk a stone quay. Flip-flops for the beach bag if you must, but the boat itself runs best barefoot, which is also the answer to the packing volume.
The small kit that earns its space
Reef-safe sunscreen in quantity, applied before the crew has to mention it. Personal medications with margin — a boat is a bad place to run out — plus your seasickness choice started before the first passage. A dry bag for the tender ride. Adapters for the boat's outlets and a spare cable for the thing you'll photograph with. Lip balm, a book per two days at most, and the paperwork: passports, sailing resumes if you're bareboating, the charter contract, and travel insurance that names the boat trip. Everything else — towels, hair dryers, toiletries beyond prescription, water toys — the boat has.
What to leave behind
Hair dryers and irons, almost always aboard. Towels, including beach towels. Diving masks you've never worn — the yacht's kit fits and is rinsed. Hard-shell luggage, more than one evening outfit per few nights, jewellery that minds salt water, drones without asking the captain first, and anything you would be upset to see go over the side, because on the water, things go over the side. Blue jeans, one concession: they never dry.
For children, the short version
Double the swimwear, one warm layer each that they will deny needing, their own lifejackets only if the yacht hasn't confirmed sizes in advance, and a single soft toy each — the boat's laundry will handle the rest. The toys the yacht carries are better than the ones at home; the toy from home is the one that sleeps aboard.