On this issue, I recommend reading Roger Marshall's "Choosing a Cruising Sailboat."
IMHO, the Halman 27 was clearly not designed as a blue water boat. I compared it to our 75-84 Hunter 27, and to a Contessa 32 which is a well known blue water design. Here are some relevant ratios, and comments:
Capsize screen. here are different opinions about this ratio, but If a designer designs a boat with a capsize screen above 2.0, that designer is clearly saying this design is not intended for ocean crossing cruises. The Halman 27 Capsize Screen is 2.01, the Hunter 27 - 1.94, and the Contessa 32 - 1.80.
Comfort is key to long cruises away from shore. Again, the Halman 27 has a low comfort ratio of 21.89. Hunter 27 - 23.73. Contessa 32 - 27.7. The Sailboat Cruising website says that 30 is the minimum for a blue water yacht, so the Contessa 32 falls a little short, and the two 27's are not really in the game. At 31.91, the Hunter 37c is an example of a boat that makes the grade.
At 32%, the Halman's ballast to displacement ratio shouts Coastal cruiser! Hunter 37 - 43%, Contessa 32 - 47%.
Length is important for the comfort ratio, the capsize screen, for average speed through the water, and for living and storage space. Marshall's idea of a blue water Voyager is 45 to 47 feet. The Contessa 32 has made many blue water passages with excellent comments. While the Admiral and I have cruised the Great Lakes on our Hunter 27 for months at a time, the longest we have gone away from a port is around a week. We might find 27 feet a little confining, if we could not get out and walk around ashore. And I would definitely question our storage capacity for cruising over a month. If I were outfitting for blue water cruising, I would like a boat like the Hunter 37c. Its more flexible cutter sail plan is another reason to like it.