We teach people to helm boats on this course. When I was 15 - before half of you were born I imagine - it wasn't like that. You joined a sailing club and crewed for people. You learned to helm over a season or two because the crew was allowed to steer the boat back to the shore after the race. There were plus points to this system, but it lacks immediacy! Nowadays, with everyone learning to helm, many more people learn to sail on single handed boats and never consider anything else. That's a pity.
Sailing is a complex sport. By the time your mind has got used to every subtlety and variation the old body is starting to give out a bit. The result of this is that sailors from 7 to 70 - and more - can enjoy sailing in the same races on even terms. Sometimes old and cunning beats young and naive, sometimes youthful brawn beats mature brain. Because there is so much to observe and assess during a race two heads are better than one. You form - ideally - a partnership, where each concentrates on different aspects of the whole challenge of the race, be it balancing and trimming the sails, or observing the changes in the wind and position of the other boats around you.
Two handed boats range from the simple - like the Enterprise and others with two sails and two people - to the more complex performance boats like (inevitably) this Cherub (below), where Claire (the crew) is not only handling a huge 3rd sail, but also doing it dangling from a wire with only her toes in contact with the boat. Both have their points. The two sail two handers - especially in inland waters - provide a platform for what can be an immensely absorbing and complex tactical match - a game of chess with 30 players and the need to sail the boat as well. On the other hand blasting from wave top to wavetop in the ultra-lightweight machines I favour is a huge adrenalin rush, but isn't always the subtlest of tactical games. There are classes to suit everyone - and about another 50 besides!
Sailing two handers can immensely speed up the learning process too. In a singlehander you have really only yourself to work out what's right or wrong, but if you sail a two handed boat with a more experienced helm or crew then you will learn far faster, because the other person will know what doing it right looks like, and can tell you. Personally I love crewing, and am much better at it than I am at helming a boat.