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Electric Bilge Pump Installation

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sailingchefs
1st Mate

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USA
28 Posts

Initially Posted - 04/13/2010 : 10:49:25

Hi all,
I tried posting this in the C-25 section on Friday, and I'm thinking that maybe posting just before the weekend wasn't the best timing...got very few responses. By your leave, I will humbly repost it here...

So I pored over the forum's bilge pump search entries for a while, followed some excellent links;http://www.yachtsurvey.com/bilge_pumps.htm,rule.com, the thread on "Proper Height of a Thru-Hull", and another thread that seemed pointed toward water-ballasted boats.
I decided to go with the Rule 2000, with it's own thru-hull, in addition to my soon to be rebuilt manual pump.This should give me, all things considered, about 1700-1800 real gallons per hour, plus a manual piston pump.
Here are some of my concerns, in no particular order:

-Suppose I wanted to be even more OCD, and install a smaller Rule 500 Fully Auto. (that I already have a couple of) in a slightly lower position in the bilge as the yachtsurvey.com page suggests. Does that necessitate yet another thru-hull, or some ingenious combination of Y's and anti-backflow devices? It does seem less of an issue than with tapping into the manual pump's hose, since the smaller, lower one would also be running and largely irrelevant if the 2000 needs to kick in. Sonnet II will be on a mooring for the summer, and although I usually get out once or twice a week, I have no good way to recharge the batteries without running the motor. (Only a tiny cheap solar panel, and no new one in the budget.) I like the idea of the tiny low-draw pump taking care of small amounts of rain water while I'm not around without killing the batteries. As everyone says, its likely to stay dry and never be an issue anyhow. Just a bit of mental comfort and extra redundency for two sailors who took turns working a 3ft. man. piston pump for 2 1/2 hours non-stop, literally for our lives,one evening last fall.

-One of the tech guys I spoke to at Catalina direct today explained to me that the anti-siphon loop was the point in the new pump's discharge hose that the water would drain back into the bilge from when the pump shut off, possibly turning it back on. I had thought to put said loop just forward of and higher than the new thru-hull, but that leaves the maximum length of hose to drain back into the bilge. See Joe Wergers' diagram in the "Proper Placement" thread. Tech guy suggested I put the loop as far forward, close to the pump, as possible. I know all the different years and models have different bilge layouts, but does any one have a strong position on the best route for the new discharge hose and placement of the loop considering this back flow issue? Maybe it's high up just forward of the manual pump in the laz.?

-And about this vent in the loop; what is it called, and who has them?
Why do they get blocked, as they apparently do?

-The DPO seems to have added 3-4 ft. of smaller diameter clear vinyl hose, through a reducer, to the end of the manual pump's pick-up hose. It does a loop back aft so the cut end rests on the floor of the bilge. Could this have been intended to prevent back flow from the manual pump? Doesn't seem like it would.
The larger, original black hose lays flat on the floor of the bilge, but from my reading, it seems it at least needs a strainer installed on the end. Agreed?

-Every one refers to the manual pump's thru-hull as being 6 inches above the waterline. As it happens, the center of my thru-hull is 3 1/2 inches above the waterline, and mine looks like all the others.
Since the top of the keel/ bottom of the bilge is not quite 2 ft. below the thru-hull, I'm thinking putting the new hole a few inches higher on the transom wouldn't be so bad. It sounded like it was placed lower not just for less static head, but to minimize splash/staining on the hull. Since this pump should never turn on anyway, not an issue right?

-About the wiring, I'll probably go with the Rule 3-way switch; wire it directly to the panel with no breaker, and mount the connections in the bilge as high as possible with shrink connectors and a dab of dielectric grease.

-Since the current motor is a pull start with a generator, I'm looking at going with 2 of the largest marine deep-cycle batteries that will fit in the battery locker. I have yet to measure this up. Anyone care to chime in on their favorites or what the max. size that will fit is? (Or just point me to the thread, I haven't gotten that far yet.)

It's late and I'm getting punchy. Time to post and retire.
Thanks, Glenn

S/V Sonnet II
'84 C-25 #4213
SR FK Trad.
Little Harbor NH

Edited by - on

Prospector
Master Marine Consultant

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Canada
3159 Posts

Response Posted - 04/13/2010 : 18:24:41

Wow. not a lot of action on this topic. I remember some pretty lively bilge pump discussions a while ago, but no dice this time. You shoulda asked how it would affect your tow vehicle ;o)

I can't add much except to say that larger is better, adn I appreciate the info you have in this post since I need to get a pump hooked up too.

Edited by - Prospector on 04/13/2010 18:25:23

Sloop Smitten
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Response Posted - 04/13/2010 : 22:10:14

Glenn,
The vent at the top of the loop is to prevent the hose from siphoning the ocean into your bilge. The vent will not allow the vacuum needed for a siphon to exist. Having the loop helps prevent any water entering the thru-hull from flowing down hill into the bilge. I am not sure why having it closer to the pump is a good idea. The bilge is so small on the C25 that a loop would be hard to make close to the pump.

Edited by - Sloop Smitten on 04/13/2010 22:10:53

jerlim
Master Marine Consultant

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1484 Posts

Response Posted - 04/16/2010 : 15:58:57

It seems that vent will allow water into the tubing...w/o it, wouldn't the pump simply hold back the air pressure and keep external water from entering??

Edited by - on

sailingchefs
1st Mate

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USA
28 Posts

Response Posted - 04/16/2010 : 18:01:13

The vent is at the top of the loop in Joe's diagram. Apparently it prevents a siphon effect of water being drawn into the boat from outside. I am concerned that the vent will fail, and need to be replaced after a while. Just another item on the occasional maintenance list I guess. I'm planning on installing the new thru hull higher on the transom than the one that is currently there.
The real worry I have is that all the water in the hose between the loop and the pump will drain back out through the pump into the small area of the bilge and re-activate the pump over and over, draining the battery. That's why I'm trying to figure out how to minimize that distance between the loop and the pump by making the loop as far forward as possible, probably right behind the elec. panel.
I still have to get a look at the hose run from the manual pump to the thru hull, and see if that needs a loop too. As close to the waterline as the thru hull is, that seems a likelier place for water siphoning in. The manual pump itself is high, just below the cockpit bench, and maybe that's enough of a rise...

Edited by - on

Bones
Deckhand

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4 Posts

Response Posted - 04/18/2010 : 22:54:51

I fixed my backflow/pump cycling problem by installing a check valve just aft of my automatic bilge pump. Is it the "right" way to do it? I don't know, I'm new at this but it seems to work so far. The miniscule amount of water returned to the bilge will not activate the pump switch.

Edited by - on

redeye
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Response Posted - 04/19/2010 : 09:38:41

<< It seems that vent will allow water into the tubing...w/o it, wouldn't the pump simply hold back the air pressure and keep external water from entering?? >>

The "vent" is a loop with a backflow check valve at the top of the loop. It lets air in and prevents a siphon of water from coming in from the outside. Without it your line would have to be full of water and your through hull would have to be below the waterline to siphon water in from the outside. That check valve would hardly ever "fail" although they often get crud in them and do not close completely allowing water to come out just a tiny bit when the pump runs. They "fail" open allowing air in which is their function, so essentially they do not fail until the valve membrane auctually rots out.

The pump is an impeller that spins inside a housing, but it is not air tight. Air can get past it and water when it is at rest. The pump will not stop a slow siphon of water.

Edited by - on

TakeFive
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Response Posted - 04/21/2010 : 21:09:28

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by redeye
...The pump is an impeller that spins inside a housing, but it is not air tight. Air can get past it and water when it is at rest. The pump will not stop a slow siphon of water...
<hr height="1" noshade id="quote"></blockquote id="quote">
...which leads to a question I've been meaning to ask about my C250. It has a manual bilge pump installed on the port coaming in the cockpit. The through-hull is very high above the water line. Based on its operation I am sure it is a diaphragm pump. I would like to add a 12v electic/automatic bilge pump to save the boat if it happens to spring a leak at the dock. (I have shore power with a charger, so the bilge pump would not drain the battery.) Since you can suck water through a centrifugal bilge pump, and you can push water through a diaphragm pump, why not simply add the electric pump onto the end of the existing hose? If the electric pump fails while I'm on the boat, I can override using the manual pump to pull the water through the electric pump. No need for an additional through-hull, or T-fittings, or additional check valves. It seems so simple.

Has anyone else with a C250 done this? What are the pitfalls?

Edited by - TakeFive on 04/21/2010 21:12:34

redeye
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Response Posted - 04/22/2010 : 05:53:01

That is a hoot! Makes me think of the quote "We put a man on the moon before we put wheels on luggage".

Sounds like a plan to me, and easy enough to test.

Edited by - on

sailingchefs
1st Mate

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Response Posted - 04/22/2010 : 07:53:48

I don't remember the exact reasons, but that arrangement was specifically discouraged in the bilge pump article I cited in the first post, and in the other threads I found here, and @Sailnet, and @Sailboatowners forums...

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delliottg
Former Mainsheet C250 Tech Editor

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4479 Posts

Response Posted - 04/22/2010 : 08:37:54

Rick,
We put in a 2000 GPH pump to a separate line routed right next to the original manual pump. There was a large discussion on the forum about the pros and cons of a separate hose, or dual use with the original. [url="http://www.catalina-capri-25s.org/forum/topic.asp?ARCHIVE=true&TOPIC_ID=18016&SearchTerms=rule,2000"]Here's my post on installing it[/url]. There's also a link to the original discussion started by Paul (britinusa) at the very top so you can read our thought process.

Hopefully that's helpful.

Edited by - delliottg on 04/22/2010 08:39:01

TakeFive
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Response Posted - 04/22/2010 : 22:05:13

Thanks for providing the links to the prior bilge pump threads. I read through them, and the objection to mounting the pump at the inlet of the current manual pump intake hose seems to be "thou must have maximum performance to protect against THE BIG GASH, and maximum redundancy for everything." In other words, biggest pump you can possibly have, largest pipe, minimum constrictions, minimum static head (although the need for anti-siphon neck makes this impossible anyway). You must be prepared for the biggest leak that will happen from hitting a submerged rock. You must anticipate that the diaphragm may rupture and therefore can't pump though it. etc etc.

I suggest a more pragmatic approach. Right now I have a manual pump with no backup. Many people have no additional protection - including the 6 used C250s I looked at while shopping around. (I never saw a single one that had an automatic pump.) If the project grows too big and complicated, I'll never get around to doing it and will continue with what I have now - like those other C250 owners. Plus, I am simply not ready to put another hole in the hull at this early stage of my ownership.

I consider my most likely mode of failure to be a small leak through the through-hull for my depth transducer (someone else installed it that way - not me) or my head intake (yes, my boat has a real head) while the boat is docked during the work week. At this stage, just getting started with my boat, I would like to have an auto pump to protect against this specific occurrence. So I plan to mount an electric/automatic pump at the intake of the current pump line. I realize that the check valves on the diaphragm pump will add a little resistance to flow, but I'll test it to see if it's still sufficient flow rate to guard against a small leak. I'll also test the manual pump to ensure that sucking through the pump's strainer does not restrict manual operation too much - and I'll make the pump easily removable in case the pump constricts the manual override.

If I hit something really big and make a gash in the hull, I doubt any pump would be big enough anyway.

Down the road I can consider a second line to have full redundancy, but for now I think the simple install is better than having no automatic pump at all.

I just got an email that Rule automatic bilge pumps are on sale at WM for the next few days, so someone's calling me to do this right now.

Edited by - on

skrenz
Captain

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USA
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Response Posted - 04/23/2010 : 12:54:45

I think the reason you don't want to discharge an electric pump through the diaphragm pump intake hose is this: diaphragm pumps use a series of flapper valves for their operation. Its easy to visualize. When you pull the pump handle for the intake stroke the outlet valve closes and the inlet valve opens. On the output stroke the inlet valve closes and the outlet valve opens. In either case, one of these valves is closed at all times. If you try to discharge your electric pump through the diaphragm pump, you will be pushing against one of these valves and it may not discharge at all.

Edited by - on

TakeFive
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Response Posted - 04/23/2010 : 15:16:39

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by skrenz
 I think the reason you don't want to discharge an electric pump through the diaphragm pump intake hose is this: diaphragm pumps use a series of flapper valves for their operation. Its easy to visualize. When you pull the pump handle for the intake stroke the outlet valve closes and the inlet valve opens. On the output stroke the inlet valve closes and the outlet valve opens. In either case, one of these valves is closed at all times. If you try to discharge your electric pump through the diaphragm pump, you will be pushing against one of these valves and it may not discharge at all.
<hr height="1" noshade id="quote"></blockquote id="quote">
I'm a chemical engineer and have seen my share of diaphragm and centrifugal pumps. The check valves on a diaphragm pump both open in the same outbound direction. So the electric pump will push them both open. There will be a little pressure drop due to the check valves, but neither check valve will completely stop flow as long as the electric pump is strong enough. Draw a picture and you'll see what I mean.

I haven't finished my design yet, but I plan to put a three-way T-valve between the automatic pump and the intake line. The "T" part will go to a short hose that leads a few inches to the very bottom of the bilge.

I will leave the T valve open straight through (closing off the third leg) as the default (unattended) position. This will allow the automatic pump to function when I am away from the boat. If I want to use the manual pump to empty the last few inches of water below the automatic pump, I can turn the T-valve to bypass the automatic pump. This will also eliminate the resistance of the automatic pump if I ever need to use the manual override aggressively.

So far my boat has never had a drop of water in its bilge, so hopefully I won't need to ever use the T valve.

I'll draw pictures someday if/when I get the thing complete.

Edited by - on

TakeFive
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Response Posted - 07/10/2010 : 20:03:19

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by RhythmDoctor
...which leads to a question I've been meaning to ask about my C250. It has a manual bilge pump installed on the port coaming in the cockpit. The through-hull is very high above the water line. Based on its operation I am sure it is a diaphragm pump. I would like to add a 12v electic/automatic bilge pump to save the boat if it happens to spring a leak at the dock. (I have shore power with a charger, so the bilge pump would not drain the battery.) Since you can suck water through a centrifugal bilge pump, and you can push water through a diaphragm pump, why not simply add the electric pump onto the end of the existing hose? If the electric pump fails while I'm on the boat, I can override using the manual pump to pull the water through the electric pump. No need for an additional through-hull, or T-fittings, or additional check valves. It seems so simple.

Has anyone else with a C250 done this? What are the pitfalls?
<hr height="1" noshade id="quote"></blockquote id="quote">
FYI, I finally got around to installing the bilge pump today. I did exactly what I described above - I added the 1100 GPM automatic pump at the intake end of the manual pump hose, and it works perfectly.

First, I did a control experiment before installing anything. I poured enough water in the bilge to prime the pump and pumped the level as low as it would go. Then I dumped 2 gallons of water in the bilge and manually pumped it out. It took me about 30 seconds.

Then I piped up the automatic pump (no electrical yet) and repeated the experiment with the manual pump, with the automatic pump in place as basically a passive strainer. It also took 30 seconds to pump out 2 gallons. The manual Whale pump pulled water through the electric pump easily.

Then I hooked up the electrical connections and dumped in enough water to start the pump. It took about 4 gallons to get the pump to activate the automatic sensor. It pushed water through the Whale pump no problem. As I indicated above, a diaphragm pump like the Whale has two flapper-type check valves, but both open in the outward direction, so the electric pump just pushes them open and water flows right through. I tried (twice) to measure a flow rate by taking my pail out to the discharge port and collecting the water, but the electric pump was so fast that I could not get there in time. I could tell by the gurgling sound that the pump works faster than water can drain through the vent holes in the ribs separating the adjacent compartments. So a faster pump would not do any better with a slow leak. The only way this pump could reach its maximum capacity would be if water was pouring in so fast that it overflowed the ribs, and if that happens it's probably time to abandon ship anyway.

The benefits of this installation is that it is extremely efficient, and easy to do a periodic test of its operation. It gives me an automatic bilge pump for slow leaks that may develop when I am away from the boat (my primary objective). It does not give me a redundant hose for the two pumps, so I will have to check the hose periodically. It also requires that the rubber diaphragms for the Whale pump be kept in good shape with no dry rot or other cracking. But both of those are things I would have to check even without the automatic pump.

So while I do not have as much redundancy as a fully independent pump install, I have most of the benefits of the automatic pump, plus a manual backup, all installed in a couple of hours of DIY work.

Edited by - on

redeye
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Response Posted - 07/12/2010 : 04:06:23

Brilliant! You deserve a Guinness ...

Edited by - on

hjohnston
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USA
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Response Posted - 08/02/2010 : 12:08:52

If you are at all in need of a great dewatering pump at this point, you should check out these specialty diaphragm pumps that are very convenient to customize and durable, so you won't have to replace them soon: http://www.ingersollrandproducts.com/IS/Category.aspx-am_en-3809

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skrenz
Captain

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Response Posted - 08/02/2010 : 14:23:35

While we are on this discussion of bilge pump outlets, I do not get at all the need to put in a vent loop to break a possible siphoning situation. Your outlet is above the waterline right? It might be below the waterline in storm conditions due to wave action but even then its not underwater all the time. How is a siphon going to get started? More to the point, if this is such a vital item, why doesn't the manual whale pump have one on its discharge line located in the same position relative to the waterline? The only time I've heard about putting in a vent line was on the supply line to a head. Here you have a line that is always below the water line and could possibly start a siphon action. But on the discharge side of a bilge pump? I don't see the need.

Edited by - on

Dave5041
Former Mainsheet Editor

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Response Posted - 08/02/2010 : 14:42:57

The discharge can be underwater when the boat is heeled. If the line is full of water, as in the bilge pimp has just cycled, you can certainly start filling the bilge, especially if the discharge through-hull is close to the waterline. The through-hull will normally be close to the waterline to reduce head for the pump and to avoid staining the hull.

Edited by - on

skrenz
Captain

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Response Posted - 08/03/2010 : 16:22:04

The normal outlet placement for the stock pump discharge is generally centered on the transom and several inches above the waterline. Although I agree its possible to get this outlet underwater "some" of the time, I can't see how even on a heel its going to be underwater enough to start a siphon effect. If using the manual pump, this hose actually goes uphill to the pump body itself. In order to start a siphon, you need a consistent water source, the hose itself full of water, and the hose dropping to a point lower than the intake. The combination of these conditions is not ever going to happen under normal conditions.

Edited by - on

Dave5041
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Response Posted - 08/03/2010 : 18:27:52

My manual pump discharge is on the port side of the transom and not infrequently submerged on a tack, but I think this has been about a new electric with a new discharge location. The intake and discharge sides of the electric pump will always be filled with water at the end of a pumping cycle triggered by the float switch. The pump intake will usually be below the waterline, and that makes it the low side of a potential siphon. Your boat and your choice, but I believe you are wrong in believing that it will never happen
<blockquote id="quote">quote:<hr height="1" noshade id="quote"> My dear sister once came on deck while crossing the Yellow Banks in the Bahamas and said, "Neil, are the floor boards supposed to float"? It depends was my answer, not wanting to sound alarmed. The bilge pump discharge had back siphoned through a lee discharge with no siphon break.<hr height="1" noshade id="quote"></blockquote id="quote"> Capt. Neil Haynes at boatsurveyor.com

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