[hkgboater]

recently flushed the engine with fresh water after use, with the engine running and the muffs fitted the hose came off so no water to engine.engine proberbly ran for max 1 min at idle before I turned it off.
1.what is likelyhood of damage to the waterpump / engine?
2.what do I need to do before running it again?

[hkeiner]

The motor probably did not overheat and is likely fine. Aside from a visual inspection of the motor for signs of melting wire and such, you can do a compression test of the cylinders for peace of mind. The impeller in the water pump, however, may have been damaged or weakened by running it dry. Even if you did a water pressure test on the cooling system and found it within specs, you can't predict how long the impeller would last if it was weakened. If it were my motor, I would replace the impeller.

Others that have actually done what you did may provide more "real-life" opinions on how likely the motor survived this experience.