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Jeff Morris
 
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Default Siphons, anti-siphons & wet exhausts

"JAXAshby" wrote in message
...
If the engine is below the waterline, its impossible to have the exhaust
manifold above the waterline.


really? see below


Yes really, its the standard, and its the law. The ABYC says a siphon break is
"recommended in applications where the exhaust manifold may be below the
waterline at any angle of heel." And the Code of Federal Regulations, 46CFR182
says that the ABYC standard is the law in this area. The CFR also says the
injection must be as close as possible to the manifold.

So while you can claim that the injection point is the important point to
measure, the law says otherwise. Failure to abide by this would certainly mean
failing a survey, and making it impossible to insure the boat.




Unless, of course, you have a "magic manifold"
that can be mounted several feet away from the engine.

You can use a special elbow to raise the injection point a few inches


"a few inches"?? at least six inches above the water line.


Actually its just 5 inches higher. When the boat is "at repose." Let it heel
45 degrees, and its only 3.5 inches higher.

and there is not a
think "special" about it. the pipe is solid bolted to the manifold, an elbow
turns the pipe **UP**, jeffies, until high enough, then the water injection
elbow is mounted, etc.


It's special in the sense that in the Yanmar parts catalog the "straight pipe"
is the standard one, while the raised elbow is listed as "optional equipment."
Admittedly, almost all sailboats would use the raised elbow. (A friend has a
new YM engine with the straight pipe, but its a catamaran with a single engine
perched a foot above the water driving a Sonic Leg.)



what word don't you understand?


I understand perfectly. Why is it that you continually claim the standard and
the law should be ignored? Its very simple: if the manifold is below the
waterline, a siphon break should be installed. Failure to do so means failing
the survey, no insurance, no marina, no sale.


but that
does not satisfy the requirement that a siphon break is required if the
manifold
is below the waterline.


jeffies, it is NOT the manifold you need to worry about (anymore than you need
to worry about where the oil pump is) BUT where the water (from outside the
hull) empties into the system, THEREFORE if the water injection point is above
the water line **there is no siphon potential**. None.


That's not what the standard says. That's not what the law says. Why are you
claiming the law should be ignored?


jeffies, this is easy stuff. as in E Z.


It sure is, jaxie, and you still don't get it.

You still haven't explained how the engine can be mounted so that the manifold
(or even the injection point) can stay above the waterline. In any center
cockpit boat, for example. the entire engine will be well below the waterline,
even before heeling is considered. Raising the injection point 5 inches still
won't help.