[C320-list] easy way to winterwise the raw water and conform to ABYC code?

[Alan Goodman]

I recently was looking through the Forespar catalog (http://www.forespar.com/pdf/M20-marelon-plumbing-product-chart.pdf) for head vent parts, and while doing so a thought occurred to me.  I have been seeking a permanent way to provide easy addition of antifreeze to flush the raw water side of the engine.  I looked at adding a Prestone radiator flush kit into the water supply hose after the raw water intake seacock, but I was concerned about (i) inability to properly double clamp the hose as per ABYC standards for below water line fittings, (ii) whether it was wise to trust a screw on type cap to seal the flush kit (leaks or failure would be very bad !!), (iii) would I pass a marine survey when I sell the boat in the future or (iv) would I jepordize my insurance coverage in the event the 'non-marine' part failed and flooded the boat.  A standard Forespar 'Y valve' (such as part number 902001 MF 853 found at http://www.forespar.com/pdf/M20-marelon-plumbing-product-chart.pdf) would provide a two source supply to the raw water system and meet all ABYC requirements.  One leg provides fresh water from the thru-hull and the other leg of the Y valve allows the antifreeze supply line to be directly plumbed into the raw water system.  Which supply stream (either raw water or anti-freeze) proceeds through the strainer and into the engine block is controlled by appropriate positioning of the Y valve handle.  Thoughts?  Alan Hull 67 Holland MI