160-165 for raw water cooled and 160-195 for fresh water cooled. The hotter you can run it, the better. But, since raw water systens are non-pressurized, they cannot operate at 195 because there will be localized hotspots above the boiling temp of water at 212 degrees. At 16 psi with coolant, systems can operate as high as 270 degrees before boiling so fresh water systems can operate hotter.