BTW, for the record, the best way to avoid capsize is to a) keep water out of the boat, and b) provide a great way for water to get back OUT of the boat. The #1 cause of capsize is the free-surface affect of water in the boat, e.g. water is heavy and sloshes to one side or the other, and it does this out of sync with what the hull is trying to do ... in other words, if a hull is trying to right itself, the water is usually (at that time) moving in the opposite direction and resisting the righting of the hull. The #1 way people get water in the boat is having a heavy stern (4 fat boys fishing, couple hundred pounds of ice, all the weight in the stern) followed by a sneaky wave coming in over the stern. Once some water gets in, the stern becomes even more heavy and more likely to take on more water. I saw a boat capsize in Puget Sound in conditions where there was only about a 2-ft chop ... they played out the scenario above perfectly and they all went swimming. Check this out: Let's say you have a cockpit that is about 6 ft by 7 ft and you took on water that was only 1 ft deep in the cockpit ... that's 6 * 7 * 1 * 62 lbs/cu. ft of weight ... 2600# !!! You think that'd have much force when it sloshes against the side of the boat? How much more likely will it be that another wave can make it in when you've got an extra 2600# in the stern? It happens in seconds...
SO, The Great Alaskan was designed to allow as many degrees of heel (roll) as possible and to strongly resist heeling ... more than most other boats in its class. The high flared sides help a lot. Keeping water out by using coaming around the cockpit and bulwarks that help prevent water draining into the boat and good seamanship are key. The icing on the cake is to provide LARGE scuppers that allow water to wash back out ASAP. Do the calcs ... your bilge pump is for incidental water, NOT getting 2600 lbs back out. Large rectangular scuppers, even (especially?) on the sides is a great idea ... the hard part is that you'd like them to be close-able until you need them. But when water gets in, the key to success is getting it back OUT and doing it FAST, before worse happens. Research those scuppers ... I do not advise on exact requirements because they vary around the world and even within some areas (USCG v. ABYC), the requirements contradict each other. Just study the info above, read available standards, and look at commercially-made boats in the same class as a Great Alaskan to see what they are doing then do the best you can ... and you're the captain, responsible for wise boat management that keeps you out of trouble... unlike that guy in Puget Sound. NOTE: If planning on a captain's license and 'inspected' status, it's the USCG rules that matter in the USA.
Brian