Coming on Board
Before you board a boat, even if you know the captain, it's customary to request permission to come on board. This is simple good manners. After all, you wouldn't walk into someone's house without knocking first. The golden rule of getting on board a boat is one hand for you, one hand for the boat.
This means you shouldn't try to board with your luggage hanging off you. Hand your luggage to whoever is on the boat first, and then board, always keeping a firm grip on the boat as you do so with at least one hand. Halfway between the jetty and the boat is not a good time to try to take a selfie!
What to wear
Sailing conditions can vary. In the summer, it's best to wear light, loose clothing and pack a waterproof jacket, as well as bringing along a pair of jeans. It's at least 10C cooler on the water, so it can feel a bit chilly in the evening. It doesn't matter how long you took putting a stylish sailing wardrobe together - take the dorky windbreaker along in case you need it. It's a lot better than shivering on the deck!
In the winter, dress warmly in layers, choosing synthetic fabrics over cotton. If you get wet, synthetics dry a lot faster.
In terms of shoes, stick to common sense. A sailboat is no place for high heels, wedges or platforms- with a boat in motion you are likely to loose your balance, and if not that the surfaces of a sailboat are hard and shiny, not a good match for stilettos. Your own injuries aside, don't forget what a precious investment a sailboat is. The owner will not appreciate the damage your fashionable shoes caused to the deck. Slippers, sneakers and canvas shoes will give you a good footing and not sending you skittering overboard. Best practice is to follow the captain's lead - you'll notice that they're nearly always barefoot.
What to bring
Bring along sunscreen, water, snacks and drinks, and bring enough to share. Luggage should be soft such as duffle bags or backpacks to store easily. Pack as economically as you can, the golden rule being once you've got together everything you think you need, cut it down by another 50%. Space is limited on boats, you don't want to take it up with luggage.
If you take medication, bring enough with you and some extra just in case. Don't rely on facilities at marinas, some are larger than others, some are no more than a jetty over the water. Pharmacies are not always easy to find.
The captain will be happy to show you what he or she is doing, as long as you ask in advance and are patient during manoeuvres. Along the same lines, don't go around pulling on ropes and pressing on buttons without asking. A sailboat is a delicately balanced vessel. Always ask before touching anything. The captain will most likely be very happy to let you get involved. Just make sure you let them show you what to do first.
Remember also that it's not the captain's job to teach you how to sail. For that, you need an instructor and a sailing school.
Fresh water is scarce on a boat. Be economical with its consumption.
Ask permission before you light up. The captain may or may not be a smoker so it's better to ask rather than assume.
You're on holiday so it's perfectly fine to have a few drinks and relax. It's bad form to get wasted on a boat. If you were a guest in someone's house, you wouldn't think it was okay to walk around their property completely wasted. Making the captain return to the marina to treat avoidable alcohol related injuries is a nuisance. Respect the boat owner, whether you rent with the captain or bareboat. Apart from bad manners, it's also unsafe to get drunk on a boat with the added factors of the effects of the sun and vicinity to open bodies of water.
Leaving the boat
Apply the same rules as you would when renting a flat or a car - return the property as you took it on. Sailboats take a lot of work to maintain. Once back at the dock, don't immediately disappear. Stick around to ask if you can help with anything, such as collecting trash, washing any dishes left in the sink or helping the captain unload his or her own things. The captain will most probably tell you no, but you'll mark yourself out as a good guest simply by asking.
For crewed vessels, it's common to leave a tip. In any case, it's not customary, but your hosts will appreciate a small gift such as a bottle of wine or a souvenir from your country.
Sailing is a unique experience. Make sure you stand out as a good guest and make lifelong friendships in the process.