On my Vineyard Vixen I raised the loop and drained it into the cockpit.
That ensured not backflow, allowed me to keep an eye to be sure water was
flowing and cleaned (a little( the cockpit sole.

--
Dennis Gibbons
S/V Dark Lady
CN35-207
email: dennis dash gibbons at worldnet dot att dot net
"Rob" wrote in message
om...
I have a YSM 12 raw water cooled Yanmar on my Catalina 30 I recently
purchased. I noticed the siphon break is installed under the sink and
vents into the sink drain. I want to replace the siphon break elbow
with a new one and vent it properly. What would be the correct
arrangement? It breaks the cooling line from the engine head to the
exhaust manifold (then vents into the sink drain). It looks rather
old and I am not sure it is even functioning properly. My raw water
pump sometimes looses its prime when I start the engine and I am
wondering if it has something to do with the siphon break not working.
I am also looking into installing a raw water flow alarm- any
recommendations with that on brands and where to install the unit?

Anyway- I was wondering how high I need to loop the siphon break and
where should it be vented. Thanks.