USCG Photo: HMDS Vaedderen, at 3,500 tons, a relatively large but simple, ice strengthened Offshore Patrol Vessel of the Thetis Class, with StanFlex modular payload capability
Considering the new Navy destroyer program, GAO identified problems that come from trying to put too much, into too small a hull. They call this problem design density. While perhaps less of a problem for the Coast Guard, this also applies to cutters like the proposed Offshore Patrol Cutter (OPC).
It may be counter-intuitive, but size alone is not necessarily a significant determinant of cost. As we noted earlier, the new largest ships in the world do not really cost that much. In fact, they cost less than the National Security Cutter (NSC), and probably less than the OPC. The GAO report indicates for a given capability, a smaller hull may actually cost more, because the density of systems may make design, construction, and maintenance more difficult. Additionally GAO notes it may lead to shorter hull life as it seems to have in some Navy ships. Certainly it is easier to provide good range and sea keeping if we use a larger hull. Both the crew and the machinery are likely subject to less motion. Larger hulls also mean more underway maintenance may be possible, because it is easier to get to the machinery.
This also goes a long way to explain why the NSC is larger than the 378s, the Fast Response Cutters are larger than the 110s, and why hopefully the the OPCs will be larger than the 210s and 270s. There is also the long term advantage of the vessels being able to take on new and unforeseen future roles, as we saw with the 327s.