In article ,
Roger Long wrote:
"Jonathan Ganz" wrote

I took a look at the WM site and found an example of a vented loop. Looks
like it might fit, but I'm not sure where yet. It can either be within a
foot or so, or it would have to be at least 3 feet away in the engine
space. I'll have to check it out.


The vent has to be above the discharge and waterline for there to be any
point to it. "within a foot or so" would be OK if you just mean the lateral
distance and not the hose length. The loop should be just as high in the
boat as you can get it, ideally, just under the deck. If your bilge
discharge is high enough above the waterline, you don't really need a vented
loop except to keep surveyors happy. My bilge discharges are just ahead of
the transom and nearly a foot above the water line so I haven't added vents
to the lines which loop even higher under the cockpit coaming. It's
something I'll probably do before going very far off shore though. If the
boat was low in the water due to flooding and the pumps stopped, a back
siphon could be created.

This is an area that I need to investigate. I was down at the boat and took some time to look at the situation that develops. It looks like there's enough back-pressure on the line that it ends up jamming the flapper against the body of the valve enough to cause it to jam (not every time, but often enough, obviously). When I get in there with a screwdriver and force it open, the water that's trapped comes shooting out with a fair amount of force.

The discharge is well above the waterline - at least 18" or so, which would mean the loop (as you point out) would have to go higher. It's not a problem at the transom... plenty of room to do that via the stern laz. I definitely need to have something to prevent backflow. We typically get following seas, even coming back from someplace local. Come back through the the Gate, as I did last Sunday, and you definitely get a big following sea.

I'm wondering if there'll be so much backflow that the pump will continue to cycle. What do you think about a vented loop near the transom as you suggest, plus a check valve near the pump? Seems like this would prevent the flooding/back siphon and give the pump a break.

"Jonathan Ganz" wrote

The discharge is well above the waterline - at least 18" or so,

But where longitudinally? It, or the top of the loop, has to be above the
waterline when the boat is heeled to the deckedge. You many not sail that
hard much, but you want the margin. If you are sailing that hard because of
trying to get off a lee shore or being unable to make sail reductions, the
last thing you need is some bilge flooding.

I definitely need to have something to prevent backflow. We typically get
following seas, even coming back from someplace local. Come back through
the the Gate, as I did last Sunday, and you definitely get a big following
sea.

The amount of water a following sea will push back down the hose isn't
likley to be significant. A plain loop up to deck level at the transom will
take care of that.

What do you think about a vented loop near the transom as you suggest,
plus a check valve near the pump?

Repeat after me, NO Check Valves, except in hose ends of hand bilge pumps to
speed priming. They will always have enough crud in them to let the water
flow back slowly and increase the chances of clogging in the other
direction. Standard electric bilge pumps don't have enough pressure head to
push crud through. They can barely clear air locks.

Check first that you really have a back flow problem. Just replace the
check valve with a nipple connector and run it. If it doesn't cycle when
you shut it off, don't worry about it.

It sounds like your discharge is in the transom, if so, just add enough hose
to create a loop right there. I wouldn't worry about the siphon break for
sailing around the bay. If you get in a situation where you are flooded
enough to bring the static waterline down 18", you'll be on the radio
anyway. The waves coming up astern are not going to push enough water into
the hose to get over a high (unvented) loop and start a siphon.

The water comes up the counter and actually immerses the bilge pump
discharges on "Strider" at full power. I once flooded the bilges a bit and
started the pumps to see if I could get a siphon going. Didn't happen.
Flow past the openings at 6.5 knots makes it pretty hard for water to flow
back into the hoses after the pumps shut off.

--
Roger Long

In article ,
Roger Long wrote:
"Jonathan Ganz" wrote

The discharge is well above the waterline - at least 18" or so,

But where longitudinally? It, or the top of the loop, has to be above the
waterline when the boat is heeled to the deckedge. You many not sail that
hard much, but you want the margin. If you are sailing that hard because of
trying to get off a lee shore or being unable to make sail reductions, the
last thing you need is some bilge flooding.

It's about two feet (perhaps a bit more) off centerline.

You can see it he

http://picasaweb.google.com/SailNOW....45247473780210

And here from the port side:

http://picasaweb.google.com/SailNOW....20053195620770

I definitely need to have something to prevent backflow. We typically get
following seas, even coming back from someplace local. Come back through
the the Gate, as I did last Sunday, and you definitely get a big following
sea.

The amount of water a following sea will push back down the hose isn't
likley to be significant. A plain loop up to deck level at the transom will
take care of that.

If that's the case, then I should try it without the vent.

What do you think about a vented loop near the transom as you suggest,
plus a check valve near the pump?

Repeat after me, NO Check Valves, except in hose ends of hand bilge pumps to
speed priming. They will always have enough crud in them to let the water
flow back slowly and increase the chances of clogging in the other
direction. Standard electric bilge pumps don't have enough pressure head to
push crud through. They can barely clear air locks.

No Check Valves.

Check first that you really have a back flow problem. Just replace the
check valve with a nipple connector and run it. If it doesn't cycle when
you shut it off, don't worry about it.

Well, there is a considerable amount of pressure after I clear the current valve with a screwdriver.

It sounds like your discharge is in the transom, if so, just add enough hose
to create a loop right there. I wouldn't worry about the siphon break for
sailing around the bay. If you get in a situation where you are flooded
enough to bring the static waterline down 18", you'll be on the radio
anyway. The waves coming up astern are not going to push enough water into
the hose to get over a high (unvented) loop and start a siphon.

I'll try it. I don't mind putting in a vented loop, however. Is there a significant down-side?

I'm more concerned about the big following seas found just offshore. We were surfing a week ago.

The water comes up the counter and actually immerses the bilge pump
discharges on "Strider" at full power. I once flooded the bilges a bit and
started the pumps to see if I could get a siphon going. Didn't happen.
Flow past the openings at 6.5 knots makes it pretty hard for water to flow
back into the hoses after the pumps shut off.

Interesting..

Here's another pic of the discharge. Not sure why I said it before, but the discharge is on the starboard side, not the port side. The port side is engine discharge. I must be dyslexic today.

http://picasaweb.google.com/SailNOW....20431152743042

"Jonathan Ganz" wrote in message
...
Here's another pic of the discharge. Not sure why I said it before, but
the discharge is on the starboard side, not the port side. The port side
is engine discharge. I must be dyslexic today.


Druglexic more like it. And not just today, everyday.

--
Gregory Hall

No need for a vented loop on those but it's probably worth putting in just
to reduce the back flow and amount of water in the bilge.

While you're at it perhaps we should revisit my current thinking on bilge
pumps ad currently done on "Strider".

The Rule, et. a., pumps often have a short life sitting in the bilge water.
Most of the water they pump is in very small amounts. The hose sized for
the pump to save your boat is large enough to cause a lot of backflow and
water in the bilge with a transom discharge. The answer to both problems is
two pumps. The first, in your current location, would be a small pump with
a 1/2 or 5/8 hose. This will easily deal with condensation, stuffing box
drips, etc. It will also make less noise and draw less current. The
second pump would be located high enough above the bilge that it will always
be dry, it can have a simple float switch because, if it is ever needed, it
will probably go on and stay on until the battery runs down. This pump
would be the largest appropriate for the hose diameter.

You could put a Tee a couple feet downstream of the vented loop and run the
small pump into that. If only the big pump was running, some water would
divert back into the bilge but, mose likely, the litte pump would already be
working against a leak that was simply faster than it could keep up with.

The ideal thing would be a second line for the primary (small) pump. I
would run this out the counter bottom just ahead of the transom.

--
Roger Long

In article ,
Roger Long wrote:
No need for a vented loop on those but it's probably worth putting in just
to reduce the back flow and amount of water in the bilge.

While you're at it perhaps we should revisit my current thinking on bilge
pumps ad currently done on "Strider".

The Rule, et. a., pumps often have a short life sitting in the bilge water.
Most of the water they pump is in very small amounts. The hose sized for
the pump to save your boat is large enough to cause a lot of backflow and
water in the bilge with a transom discharge. The answer to both problems is
two pumps. The first, in your current location, would be a small pump with
a 1/2 or 5/8 hose. This will easily deal with condensation, stuffing box
drips, etc. It will also make less noise and draw less current. The
second pump would be located high enough above the bilge that it will always
be dry, it can have a simple float switch because, if it is ever needed, it
will probably go on and stay on until the battery runs down. This pump
would be the largest appropriate for the hose diameter.

You could put a Tee a couple feet downstream of the vented loop and run the
small pump into that. If only the big pump was running, some water would
divert back into the bilge but, mose likely, the litte pump would already be
working against a leak that was simply faster than it could keep up with.

The ideal thing would be a second line for the primary (small) pump. I
would run this out the counter bottom just ahead of the transom.

I was also thinking about a second pump at some point. Right now, I have two... one for the primary and one for the shower sump. But neither would help much for a major leak.

In article ,
wrote:
On Wed, 02 Jul 2008 21:11:21 -0500, lid (Jonathan
Ganz) wrote:

Here's another pic of the discharge. Not sure why I said it before, but the discharge is on
the starboard side, not the port side. The port side is engine discharge. I must be dyslexic
today.

http://picasaweb.google.com/SailNOW....20431152743042


Congrats on your "funny" this morning!

I had one posted too long ago.

I laughed when my friend sent it too me... haven't see it show it yet here though. I knew it was accepted, but sometimes they change things.