Your originial question asked about 10" and 13" seacoast mortors only but there were other types that could have been in the mortor boats. The most most likely to be in the mortor boats was the 13" seacoast mortor model 1861. Production of this mortor was 162 mortors, used by the navy as well as the army and they are known to have been used on the Mississippi river, starting in the spring 1862 at Island #10, Ft Pillow, Ft St. Phillip, Ft Jackson, Ft Pulaski and the Peninsula campaign. The famous Dictator used at Petersburg was of this type. Survivors number 27 mortors. Also made were Siege Mortors of 8" and 10" of model m1840 and model m1861 that could have been used in the mortor boats. However, the m1861 13" mortor is most likely the type used on the rivers.