One of those adjustable nozzles for the hose is useful as you can set the water flow to match the engine rpm and have a cuppa while your oil warms up.
I also take the thermostat out before I flush through with a bucketful of antifreeze mix (Volvo 2002 raw cooled).
It will not be difficult Mein Fuhrer! Nuclear reactors could.... heh, I'm sorry, Mr. President.
Thanks all for your very helpful advice.
Do as others have suggested,but make sure that your chocks are secure and do not vibdate loose. this is often over-looked.
I do exactly as you suggest for a final flush with fresh water, having changed the oil when afloat. With a Vetus strainer a hosepipe with a pistol type nozzle can easily cope with the demands of a Yanmar 3GM.
However, you need to run the engine for at least five minutes before an oil change and I suspect there may be too many opportunities for the pump to run dry if using this method. In this case I put a bucket in the cockpit, constantly topped up with a hosepipe. Then run a length of tubing from the bucket to the pump suction. Tie it to the bucket handle in case it falls out.
I use a piece of hose to connect the engine cooling water intake to the galley fresh water. Start the engine, and you get three jobs done at once. Engine warm for oil change, cooling system flushed with fresh and the water tank drained!
As mentioned above, the water will not circulate unless you remove the thermostat from its housing.
Try and do it in slings when the boat is lifted, before it's chocked off. A lunchtime lift facilitates this.
Next time, it'll all be different.
From your reply you seem to assume that the engine is raw water cooled? I must admit I didn't get that impression.
If the engine has a heat exchanger then the position of the engine thermostat is neither here nore there?
The engine (fresh water system c/w anti freeze) is sealed from the raw water side. All I'm saying is that if you want to put a/f into the raw water side then once the engine is running you can add it at anytime.
Maybe I've had a senior moment and got it wrong?