I’ve come across an interesting innovation that the Coast Guard might want to take a look at. This could be very useful in responding to flooding emergencies that seem to be becoming more common and might be useful for SAR or AtoN support in some areas. They are apparently made in Michigan. They come in two sizes, 30 ft. (9.15 meter) and 21.9 foot (6.7 meter) They are a good deal faster than the WWII vintage DUKW. There is also a personal watercraft sized version.