The rated hours before re build of the upper end is about 10,000 hours and this engine has 1,225 hours after that rebuild. The rated hours for the lower end re build is every 20,000 hours so that re build has not yet taken place. The seller has a complete spare 2nd engine Cat D 399 which is available for an additional 75,000. The main engine is air start. There are 2 air compressors both ten horsepower. One is a Quincy 325 and the other is Ingersol Rand. twelve volt, 4 batteries charged by generator There are 3 diesel powered generators. There is no holding tank because this boat has a MSD Micro Phor overboard system. This 100 Steel Coastal Tug was built for the navy and is designated YTB 387. It is of the Bushey design as specified for the Navy. It was built in 1944 but went into storage in Bremerton WA until going into service in 1974. Waterline Boats Boatshed does not independently verify dimensions and capacities, which are reported from literature and or seller s details.