Hummmm...........just thought i'd come clean on the above cooling water problem.
after one weekend of reduced revs i decided that time to have a good root through the possible problems:
fuel and carbs were fine
took out the bottom cylinder plug.....AARRGGHHH water in the cylinder..
the head gasket has failed around the bottom pot.
Lucklily i hope i've caught it in time and its in the hands with spares ready of a marine engineer.
I followed advise of two outboard engineers and filled the pot with oil and turned it over a few times to stop the water getting down to the crank.
He seems content that no more stripping is needed so hopefully it'll be running again next week.
Ones thing for sure the other one will have its gasket done next winter for sure.