"JAXAshby" wrote in message
...
The output of the water (in a
wet exhaust system) is the exhaust pipe just after the exhaust manifold

no, it is not. the water injection point is quite a bit after the enhaust
manifold in all low mounted engines.

Sailboats (and other low mounted engines) often has an elbow that raises the
exhaust several inches which then feeds into the injection loop. The net affect
is to raise the injection point several inches and provide a bit of protection.
However, the ABYC standards recommend a siphon break if the manifold is below
the water line, not just the injection point.

Here's the diagram of the new Yanmar 3YM30 with both versions of the exhaust.
Even the high version only raises the injection point a few inches. The exhaust
manifold is clearly less than a foot above the prop shaft, so a very long shaft
and an extreme down angle would be required to satisfy the ABYC requirement with
no siphon break.
http://www.yanmarmarine.com/downloads/drawings/3YM20%20(with%20KM2P-1).pdf


This is done to get the water injection
point well above the water line to avoid eventual troubles.