Monohulls can lose their keels and capsize... they can also downflood and sink. They have a position of ultimate stability, sitting up right on the bottom of the sea... If I have a choice between a boat upright, sitting on the bottom of the ocean and an inverted multihull, I know which I'd choose, since I don't have gills.
Both have their pros and cons, and both have pretty and ugly boats in their camp...
As for the arguments about costs and such... yes, multihulls are generally more expensive than monohulls at a given LOA. However, it depends on what you want to do with the boat... to some, making a passage in 20% less time is worth a lot... or being able to sail at 10-12 knots on a regular basis. Others like having the boat heeled, the rail in the water and watching the spray flying.... I'd point out that multihulls are far less expensive in terms of their performance than monohulls are. My little 28' trimaran runs down 40' monohulls pretty regularly.
Some catamarans and trimarans can fit in a standard slip. The Gemini 105Mc is such a catamaran, and the Dragonflies, Corsairs and Telstar 28 trimarans are such as well. If you're only interested in staying in marinas...then a monohull may make sense, but I think that's a specious argument....most long distance cruisers I've spoken with don't marina hop... they anchor out, pickup moorings, and avoid getting a slip to avoid the hit on their cruising kitty. Marina slips tend to be very expensive compared to anchoring out or using a mooring.
Trimarans tend to be less spacious than a monohull of equal LOA, unless it is an older, full-wingdeck design. Catamarans tend to have more space than monohulls of equal LOA. Monohulls tend to have the greatest cargo carrying capacity, but if cargo capacity is so important to you, get a barge...
There are monohulls and multihulls that sail well, and ones that sail like pigs with club feet, so that's a wash.
Having an extremely shallow draft can have serious advantages, as you often have more places you can anchor and a greater selection of hurricane holes to hide in. You can also often find anchorages and slips that deeper draft craft can't take advantage of. Combine this with a daggerboard or centerboard with a kickup rudder setup, you can have the advantages of good windward performance as well as shallow draft.
I'd point out that the Polynesians settled an area larger than North America to windward consisting of a large number of tiny islands in MULTIHULLS... Their navigation and seamanship skills were far better than those of the Europeans of the time.
The idea that monohulls are the only proper type of sailboat is a euro-centric viewpoint. If we had all grown up with multihulls and someone came along and said that getting rid of the multiple hulls and adding a huge metal weight to keep the boat upright was a good idea, he'd have been thought of as crazy....
Originally Posted by Boasun
Mono-hulls can be knocked down and rolled over and they come right back up.
Multi-hulls are knocked down and they stay up-side down until you can get a crane to right them.
Guess which one I will choose...