We operate a few of those hatchless box carriers too but only in short sea shipping. It shortens loading time in the feeder business. But I have no idea wheather this approach would be granted for a large passenger carrying SOLAS yacht like SY "A". Maybe KIWI knows? There are some precautions required like a higher bulkwark around the cargo hold and redundant pumps. But the forward cargo hold has always to be hatched by rule. Ugly ships but they make money .