On Sun, 23 May 2004 09:44:42 +1000, "K. Smith"
wrote:


Why?? Fuel or gas leaks?? (hope not)

None.........

Once the motor is running at some revs it's sucking in more air than
any blower is likely to move; indeed leaving the blower on at cruise is
robbing the motor of free air supply or at least trying to.

I was under the impression that air was circulated while running, via
an intake/suction effect through the bilge vents. I don't see how the
engines running at high rev's could draw air into the bilge, as
there's no fan or other means of generating suction.

Assuming your engine room is reasonably well sealed, that could be part
of the problem for the blowers??? struggling against the inrushing air
trying to feed the motor??

I don't run the blowers at cruise, as the venturi effect is sufficient
to keep the bilge vented, but it's my "operating procedure," if you
will, to operate them while the generator is running, before start-up
of course, and while idling.

I also have a fume detector in the bilge which is run 100% of the time
I'm on the boat.

On Mon, 24 May 2004 12:30:14 GMT, wrote:

I don't run the blowers at cruise, as the venturi effect is sufficient
to keep the bilge vented, but it's my "operating procedure," if you
will, to operate them while the generator is running, before start-up
of course, and while idling.

==================================

Nothing wrong with that, good practices in my opinion. You just need
to get a heavy duty blower, which as you have found out, does not
apply to the plastic inline models.

Another poster referred to the engines "drawing air out of the engine
room". That does happen to some extent since the engines draw in air
through the intake manifolds to support the cumbustion process.

You can try an 12V automotive radiator fan mounted directly over the exhaust
vent. They last a long time, push alot of air, and are easy to replace.

I seen one boat with multiple computer fans. 4 or more small fans mounted on
a frame. If one fan dies, the rest keep going. Plus the fans cost $5 each at
any electronics surplus store.

Same princple applies to cheaply Air Conditioning a cabin.

The computer fans are mounted on a square frame.
2 reusable home air conditioning filters act as dust catchers for the front
and rear.
A very small water fountain or bilge pump circulates cold sea or fresh water
into a trickle copper tubing array.
The fans simply blow warm air into the array, and out comes nice cool air...

I can provide you a diagram if you like. You can alter the setup to suit
your needs.

Jim Rojas


"Wayne.B" wrote in message
...
On Mon, 24 May 2004 12:30:14 GMT, wrote:

I don't run the blowers at cruise, as the venturi effect is sufficient
to keep the bilge vented, but it's my "operating procedure," if you
will, to operate them while the generator is running, before start-up
of course, and while idling.

==================================

Nothing wrong with that, good practices in my opinion. You just need
to get a heavy duty blower, which as you have found out, does not
apply to the plastic inline models.

Another poster referred to the engines "drawing air out of the engine
room". That does happen to some extent since the engines draw in air
through the intake manifolds to support the cumbustion process.

wrote:
On Sun, 23 May 2004 09:44:42 +1000, "K. Smith"
wrote:



Why?? Fuel or gas leaks?? (hope not)


None.........


Once the motor is running at some revs it's sucking in more air than
any blower is likely to move; indeed leaving the blower on at cruise is
robbing the motor of free air supply or at least trying to.


I was under the impression that air was circulated while running, via
an intake/suction effect through the bilge vents. I don't see how the
engines running at high rev's could draw air into the bilge, as
there's no fan or other means of generating suction.

It goes down through the same pipe, once you turn the fan off:-) or
even if you don't (hence the short life), because when the engine is at
some revs, it's scavenging air anywhere it can get it. Lots of
installations rely upon the flow back down that pipe (after the fan is
off) to feed the engine extra air at revs. Any stray fumes in the e/r
will be going into the engine anyway. Don't wash a diesel with degreaser
then start it to dry things out, it'll very unhappily & noisily rev
madly away till it's sucked in the very last of the fumes in the engine
room:-)



Assuming your engine room is reasonably well sealed, that could be part
of the problem for the blowers??? struggling against the inrushing air
trying to feed the motor??


I don't run the blowers at cruise, as the venturi effect is sufficient
to keep the bilge vented, but it's my "operating procedure," if you
will, to operate them while the generator is running, before start-up
of course, and while idling.

Yes that's normal to turn it back on if you slow to sustained low revs
but once at cruise revs & above it's normal to turn the blower off,
unless you have a specific reason.

I also have a fume detector in the bilge which is run 100% of the time
I'm on the boat.

Good idea & they work well, however still not as well as your nose,
which is particularly sensitive to petrol smells.

Thanks for the update & it seems maybe we're agreed; you don't really
need the fan "continuously"? It's to purge the e/r prior to start &
maybe can't hurt if at sustained low revs.

K

On Tue, 25 May 2004 20:52:13 +1000, "K. Smith"
wrote:

Thanks for the update & it seems maybe we're agreed; you don't really
need the fan "continuously"? It's to purge the e/r prior to start &
maybe can't hurt if at sustained low revs.


I mention "continuous duty" because there are a lot of lengthy idle
speed zones where I operate, so the blowers are used significantly
more than I think the typical in-line blower is designed for. As
such, after a single season of use, one or both is screeching. What
I'm looking for is a higher quality blower that's specifically
designed for continuous duty, as I believe it will last much longer
than the typical Atwood blower.......