Engine Flushing Through Sea Strainer

Do you mean that your yard stored the boat without flushing the engines and filling them with antifreeze first?
You'd better move the boat elsewhere, methink.
Anyhow, the answer to your question is no.

The water would not get past the impeller.

Assuming the engine was running at idle and the cover nipple was connected to garden hose water, the big concern would be the huge required volume of water versus the very small available volume of water.

Examine the engine raw water hose size and compare that to the much smaller garden hose fitting size.

It is likely that the raw water pump cavitation would happen with that operational configuration.

Pump cavitation is never going to happen if the water from the connected hose is pressurized, which of course it would be.

And it's pointless to compare the strainer size with the garden hose, because the former is designed for the maximum flow at 2300 rpm, while the latter must only cope with the demand at the idle speed of 650 rpm.
Now, that looks like a 3" strainer with a 3/4" hose tail on the lid. And if so, I can confirm that the flow is sufficient for feeding the MAN V10 running at idle, of course assuming a good incoming flow from the connected hose.
On the other hand, if that's only a standard 1/2" hose tail instead, I'd rather go larger.
Actually, I'd rather do something different anyhow, fitting a valve upstream of the hose tail, for rather obvious practical reasons.

Regardless, that's not what the OP asked, because he wants to "run fresh water directly in the strainer without cracking the engine", whereas by cracking he meant cranking, I suppose.
In other words, he was thinking to flush the engine just by forcing fresh water through the hose tail, which is the reason why my first short answer to him was no.
If you don't mind cranking the engine and keep it running at idle for a while (and I don't see why it should be a problem, unless forbidden by some yard where the boat is stored inside), what I explained in this post is imho the most practical way to skin this particular cat.

On my engine it would be fine as it is down hill out the stern from the shower heads.... but yours may be different and water MAY work its way into the turbo(s) and then exhaust manifold when there is no combustion pressure. Some engines do have this incredibly stupid setup. I would not take the words of people here... I would get a hold of a mechanic who knows your engine.

Positively +1 to what Oscarvan said, also because it doesn't depend only on the engine.
Also how a wet exhaust and its raw water re-injection (or shower heads, as Oscarvan called them) is built affects the risk of water reversal into the turbo, possibly down inside some cylinder, with potentially catastrophic consequences.
Ideally, you would want to talk not only with someone who knows your engines like the back of his hand, but also your exhaust system - which depends more on each boatbuilder, rather than engine manufacturer.
Though a good mechanic should be able to evaluate and asses the inherent risk of any exhaust system after a careful inspection.

Leave it this time around .
The risks of water getting into an expensive repair position by next season far outweighs any theoretical corrosion mitigation .

I'm a fan of engine flushing in general, but without knowing for sure that there's no risk of water reversal, Fiammetta's suggestion does make sense.
Unless the boat is in an environment subject to freezing, of course.
Engines neither like water in some cylinders, nor ice expanding inside them.
You don't want to jump out of the frying pan into the fire!

Yes only in the wster, IMO could this be done easily
Close of sea cock , feed the strainer with fresh water start the engine at idle RPM . For a few minutes run it .
Kill it .
Then run it with through with a few jugs of antifreeze.
Kill it again .
Do not start it again .
Haul the boat and Store it for the winter.
Done .

Hindsight is a great thing, but the OP boat is already on the hard, stored in a place where turning the engines on is forbidden...

Evidently you're not concerned with a hard freeze where you're located. So no need to flush it. Leave it and enjoy your winter. She'll be waiting for you in a couple of months and be fine. People in So. Florida leave their boats for months on end in the water and the water there is real salty. No problem. In theory you could attach a hose and run her at idle, but do you know what your water pressure is. I remember visiting my mother's cousin in Ireland whose water barely trickled from the shower. Not worth the risk. Leave it. You'll be fine.

The risk you describe does exist, but it's very easy to avoid it.
After you open the fresh water valve on the hose attached to the strainer, and you close the raw water seacock, if the engine pump demands more water than the hose can supply, you will immediately notice that the rubber hose gets squeezed, due to suction from the engine pump.
And of course, if that happens, the flush must be postponed till a decent fresh water flow is available.

For this purpose, below is a photo of one trick which I didn't mention in the thread that I linked at the end of my previous post #5:
a simple "Y" split hose, that allows to connect the (white) engine flush hose to two taps in parallel, granting a higher flow.
I normally don't need it in my home marina, but it came in handy in some others.

If the hose collapses from too much draw you won't have long before damage occurs. I think if I were to try that I'd take the water from a barrel fed by the hose so you have plenty of warning. However I think the point is moot since he's not able to run the motors where it's stored.

Yep, moot point.
But just for the records, you can trust me if I tell you that there's not a snowball chance in hell to starve the engine of raw water, if you know what you are doing. Been there, done that, many times.
It's actually easier done than said, but whenever in doubt about how adequate the fresh water flow is, I do as follows:
Firstly, I turn on the engine and keep it idling, with the fresh water hose already attached but its valve closed.
Then, I open the fresh water valve completely, and start closing the seacock slowly.
Now, if the fresh water flow is good enough, the hose will not collapse, and the strainer will stay full, till the seacock will be fully closed.
At that point, you can keep flushing the engine for as long as you wish.
But if while closing the seacock you'll see that the hose starts collapsing, and/or you see any void in the strainer, you can simply re-open the seacock right away, and postpone the flush.
It only takes half a minute of attention, really - much less than it took me now to write about it!

Yeah, the above setup is strictly meant for flushing an engine at idle, that's a given.
I do understand that an engine with a 3" strainer can't be ran at WOT feeding it with a 3/4" hose!

Do any of you guys add any salt neutralizer to your flush regimen? I had installed a reservoir and two electric valves via 1/2 inch hoses to the top of my strainers. Just prior to shut down after engines were cooled down I activated the wireless valves for 45 seconds or until I saw foam in the water at thr exhaust outlets and then shut down the engines. This way I never worried about starving the pumps of water flow. Of course I had to have faith that the Salt away worked. I always wanted to pull a sample of the treated water and have it tested to see if the solution actually worked. I had Cummins 8.3QSCs on the Searay 44. I am buying a Carver 506 with Volvo TAMD74s and plan on adding a system to it. On my 2008 Rinker 350 with Volvo Penta 350s there was a Neutralizer factory installed,
Rusty