Over the past two months Working Waterfront has reported on the launchings of two replica ships, DISCOVERY in Boothbay and GODSPEED in Rockport. Both reflect a growing and commendable willingness to invest in “living” history; both were built in Maine yards because that’s where the skills are. Meanwhile, Portland is about to welcome The Cat , which will provide high-speed ferry service to Yarmouth, Nova Scotia. The Cat is controversial because of its speed and the need to operate in foggy waters frequented by fishermen and others in small boats. The safety issues are real, but it’s reassuring to know that the Coast Guard, Bay Ferries, Portland’s harbormaster and others have given them some thought in advance.