Response Boat, Medium (RB-M). Photo from Vigor
A friend (thanks Lee) brought this little book to my attention.
“Boats of the United States Coast Guard”
Don’t know how I missed this, but seems very comprehensive, 30 pages and 44 different types of craft.
Image: Grupo Lindley / Administração dos Portos do Douro, Leixões e Viana do Castelo
Definitely not in my wheelhouse since I never did inland aids to navigation, but Marine Link reports an innovation in marking shallows and narrow channels in flood prone rivers. Apparently it is a hybrid between marking with a pylon mounted aid and a buoy.
Thanks to Lee for bringing this to my attention.
Chuck Hill's CG Blog 