The rule says the sailor must be able to right the boat but this includes using any dependable righting aid you can think off.

Personally, I have never failed to right my 120 kg F16 with alu mast. I'm 86 kg and 1.85 mtr tall. As the others say it does get more difficult with lighter winds. The hardest conditions to right the boat in are no waves and no wind. Having said that, the F16's are the most easily righted catamarans on the market today after the A-cats and possibly the Swell Shadow. For example, I was not able to right the Hobie FX-one with just the righting line in anything under 15 knots with waves.

The easy of righting a F16 means that lighter skippers can right the boat with relatively simple aids like the earlier mentioned trashbag. The vast majority of other designs typically need more elaborate schemes (when righting singlehandedly)

Opting for a F16 carbon mast over an F16 alu mast wins you about 10 kg's of righting weight. Meaning you can right the boat with 10 kg less on the righting line. This seems to tie in well with the experience covered by others in the thread. When it comes to survival then removing the mainsail from the mast (hard work BUT can be done during a capsize) will win you another 15 to 20 kg. The threshold for F16's under ALL conditions seems to be just over 75 kg, making survival possible for anybody over 60 kg (as you do carry a peddle on your boat right ? Or are prepared to peddle with your hands).

As a last remark, there will always be some weight below which righting a catamaran will not be viable. Here in the F16 class we define righting under ALL possible conditions including no winds or waves (hardest). Lots of others just assume that you don't capsize below 10 knots and that results in a significant difference in quoted righting weight.