It isn't really that simple to say that cats are better than monohulls. Weather that will flip a cat might just have the monohull sway down then recover since the cat's natural center of balance is updside down. Cats also seem to require more babysitting to prevent this flipping from occurring. Let's say you're crossing an entire ocean by yourself and obviously have to go to sleep at some point. With a monohull, you can toss out a drogue, then as long as you aren't in huge waves, you're probably not going to wake up in a bad situation.
With the cat, sailing alone is more risky because you really want to have someone at the helm unless the sea is entirely flat. There are cats you might not have problems in, but those cats are generally insanely expensive compared to a monohull that you can do the same crossing with. Etap monohulls are supposedly also unsinkable due to having 2 hulls with foam between.
I would personally rather have a cat, but going to sleep in a small one in non-ideal weather conditions would be scary.
There are no perfect all weather sail boats. They all have weakness and strength. What I like with the cat is the way it handles in shallow water. You may not be crossing the ocean in bad weather all the time, but you would try to be as close possible to land a lot for food, water many times. Some monohulls can deal in shallow water too obviously.
Those links are for all reading this thread.
http://westcoastmultihulls.com/multihull-vs-monohull-advantages/Safety – Unsinkability
There are many aspects to safety where catamarans and trimarans shine. Often overlooked is the safety margin introduced with level sailing (see above). It is much easier to keep crew aboard in rough weather when the boat stays level and is pitching less. Large cockpit spaces keep crew well away from the lifelines as well.
The speed of a multihull is another safety factor, as with decent weather information it’s relatively easy to sail around severe weather systems before they can bear down on you. Should something go horribly awry, and the boat get flipped (VERY rare – see below), the lack of ballast, and additional positive flotation, means that nearly every catamaran and trimaran produced in the last few decades will remain on the surface of the water, rightside up or not, until a rescue can be made. Nearly all cruising cats and tris have a substantial amount of reserve buoyancy, in the form of closed-cell foam, stashed in the nooks and crannies of the boat. Because of this, most could literally be cut into pieces and all pieces would still float. This makes fire your biggest safety concern aboard a cat. And the anchor windlass, but that’s a story for another day.
Can my catamaran or trimaran flip over?
This is theoretically possible, and has happened in very rare heavy-weather situations when EVERY vessel is in distress. It takes very high winds, too much sail (see reefing, above), and large breaking waves to flip a modern cruising cat or tri. Multihull sailors find it reassuring to know that their cat or tri will remain on the surface, as a big liferaft and spotting target, while ballasted monohulls caught in the same situation are more likely to end up on the bottom of the sea, with their crew bobbing around (if they are lucky) in an inflatable liferaft.
Motoring Performance/Maneuverability
Cruising catamarans and trimarans, with their easily driven hull forms and light weight, enjoy excellent fuel efficiency when compared to monohulls, and track very straight. Cats almost always have twin engines, set many feet apart, which allow for tremendous control in tight situations. In fact, the boat can be spun in place or crabbed sideways without any way on. Try that on a monohull. Prop walk is minimal or nonexistent as well, and the redundancy of a second engine is appreciated should a mechanical issue arise underway.
Nearly all trimarans have just one engine, so the differences there are slight.
http://www.aeroyacht.com/catamaran-learning-center-2/catamaran-shallow-draft/http://www.distantshores.ca/boatblog_files/category-southerly-boats.php
Anyway I can still enjoy my neighbor's Dufour T7 while dreaming of my perfect cat...
