Hi Mary

There is a good article on multihull seaworthyness.
http://www.steamradio.com/JSYD/Articles/NESTalk.html

It is difficult to address the capsize aspect without rethinking and redesigning a large cat or tri in total context. -
In attempting to fix one problem ,--say adding a large mast float ,--you just caused 5 more major problems in claiming it can right a boat ,-Stay strength ,-mast strength ,-mast base ,-fittings and hardware ,---
all prone to fail in extreme conditions in wind alone ,-now add huge seas and water forces . Worst of all the weight windarge of the mast float increases moment and the likelyhood of capsize , counter productive .

Long ago worked out a larger cat design for fun and addressed the capsize righting problem .
-We take monohull rigs and place them on very different catamaran configuration platforms with very different characteristics and expect them to work well --??

-A solution ,--again 20 years ago ,-designed was using a basic A FRAME support in place of stays . We see a very simple version ,-similar rig used in small scale on the catyak 12 design .
The A Frame has numerous structural advantages , triangles being extremely strong and stable . Many are used in easy mast stepping and for larger masts .
The A FRAME could of course be designed in a much more sophisticated configuration ,-arodynamic C F foil shapes -pivoting base ,etc.
Without going into alot of detail ,-the basic righting concept from inverted capsize is bows over sterns using the A frame mast rig as the lever arm. -It would be lowered beyond the inverted hull bows, an inflatable or Zodiac could be attached to the top.
Using a deck winch the volume of bouyancy along with A frame strength and stability ,--per Jakes engineering diagram ,--has the capability required.
This has to be combined with proper design --{see article}
Along with a refined A frame rig concept .--Something very different -but really needed for larger cat design .
The other important design feature was the open transom -stern area reserse sheer line design we now often see on larger cats with open transom and boarding ladder. The Benautieau designs are typical ,-very beautiful cats.
This along with fuel tanks water ,-engine all being located far aft . In some a partial water tank ballast or seperate stern bulkhead and flooding aft compartment may be needed per stern design . Reasonable Beam to L in design is also needed.
This allows the stern to submerge partially greatly reducing the center pivot point , bringing it closer to the water surface in turn requiring much less force in the righting equation.

Built an angulating rig as an experiment using this type of A FRAME support --This version -configuration added the tilting
feature though on a 20 ft cat , righting was not the idea ,-lift from the angled mast and speed was.

The mast supported by forward A FRAME support was stepped on a traveler on the mid crossbeam . As you pulled the mast base towards one hull or the other the rig would angle back and to windward per geometry . The A FRAME base was approx 5 ft forward of the crossbeam -mast location.
A noted designer builder Chris White designed a similar A Frame rig configuration on a proa at that time .
A fun experiment but not practical . Similar A FRAME configurations are however very practicle for cat design and should be developed with this righting system in mind .

Fun stuff --hope this helps -
Carl