..installed on my 1995 'Hunter 29.5' By the temp gauge installed lately , it looks the temp goes-after 20-30 min on 2500rpm or more , to about 90-95 degrees Celsius , especially in summer , when sea water temp gets to 28-30 Celsius ( Mediteranean). the alarm doesn't sound , but to me it looks a little high.All other effecting components were cheked and found OK.( the engine has just few hundreds hours) The sender was installed in place of the draining tube of heat exchanger , since the standard place( for alarm sender) is not deep enough for the longer temp sender. There is not any cooling water loose. What are the expected cooling water temp for this engine? How important-and how often- cooling water has to be replaced?