FScot's a good boat -- 850 lbs isn't that heavy, and it moves okay in a good wind. More stable and forgiving than some boats in that class. Slightly more racy, but still manageable, is the Lightning
. It's also sloop-rigged, if that's what they are interested in, 750 lbs, can be sailed by one to five people. Lots of them around at a wide range of prices. The hard chines make it stable for beginners when sailed cautiously; hook your feet under the hiking straps, power up, and it's one wild ride.
Among the most enduring designs out there.
I sail a Buccaneer18
, which is also common, also cheep, also simple to rig and quite fast. But it is a BEAST of a boat and I cannot recommend it for new sailors unless they are fully willing to swim a little. If they are, and if they can handle the learning curve, it's a stitch at 500 lbs. Best with two to three people. Chop three feet off the transom, reduce sail area, and you have the Mutineer, altogether better-mannered and available for beer money. Not so much fun as the Bucc, tho!
Small catboats are great to learn on, having only one sail. They can often serve as rowboats, too. Other boats to look for: Snipes, Capris, small Hunters, Americans. Most important thing is for your friends to get an inexpensive boat in sail-ready condition, nevermind aesthetics or pedigree. Get out on the thing, flounder helplessly, learn how to make it go. Then learn how to make it go better. After one summer of that, they'll know if sailing is their bag & what they want in a boat. They can sell their first one for the buying price and the story begins.