I bought a 10 quart Chef's design pressure cooker when we moved aboard (up from a 6 quart we used at home. I had two reasons for doing this:
1. Its the "big pot" for use at sea where the tall sides keep small amounts of
food from sloshing out. If it is rough enough Ill even use if with 2" of
water to heat up hot
dogs. The "Big pot" is also useful for big
food, like crabs and smallish lobsters.
2. Anything smaller than 10 quarts is not very practical for canning food in quart jars. It does not take a significantly greater amount of
fuel to process three quart jars simultaneously, as opposed to one quart jar. It takes three times the
fuel to process three jars separately, to say nothing of keeping the unprocessed stuff in the
galley waiting for its turn in the pressure cooker.
A very small pressure cooker can be too short to accept quart jars because they are too tall.
3. We bought some nesting cookware at a
boat show. All but one of the pans and lids (and the plastic covers for food storage) in the set will nest together and fit inside the pressure cooker so the space occupied by by the pressure cooker is not significantly more than the space required to store the rest of the cookware.
If I were you I would try to convince the skipper that he is way better off with jars of home made curry that you pressure canned. Its much better than the
commercial canned stuff. When you cook a complex recipe it is not much harder to make a gallon than to make a quart. If you can three of the 4 quarts you have some first class "fast food" in reserve.