Flushing inboards, muddy waters

[guyd]

I'm in Watchet, a pretty muddy place, and the Bristol channel is pretty muddy too.

I'm considering adding a fresh water flush.option to the intake, closing off the seacock with engine off, connecting the marina garden hose supply to a Tee in said pipe.

1. Will the impeller allow water past it when not running.

2 if not, is a hose enough water for tickover on a VW 150hp 5cyl 2.5L engine?

3 is it worth doing?

 

[A1Sailor]

Water may get past the impellor - but if you flush your raw water system without the engine running water may get from the exhaust elbow then up into your cylinders. So definitely not worth doing! (It might depend on the engine, though.)
A previous boat of mine had one of these on the raw water intake:

You just closed the seacock then unscrewed the top - then kept the reservoir topped up with fresh water while the engine was running. I used two 2 gallon cans, with the empty topped up from a hose by a friend in the cockpit. Definitely a job for two people...
Could you attach a large funnel to your Tee, to act as a reservoir? You might be surprised how much water your engine draws, even at low revs.

Edit: Your engine manual might tell you how much raw water gets drawn at various revs.
ReEdit: Sorry - I didn't say what "it" is! It is a Vetus Cooling water strainer. Info here: https://www.vetus-shop.com/vetus-raw-water-strainer-type-140-inlet-and216-19mm-p-1019.html
It will be too small for use with a 150HP engine (mine was 11HP!), but you could perhaps plumb one in attached to your Tee to make regular flushing, at low revs, easy.
Another thought is why not just get a large bucket of water, put a hose from your "Tee" into it and keep the bucket adequately topped up with your fresh water hose. That way the engine can draw as much water as it needs.