Bilge pump discharges

[sailingharry]

My boat has 4 "bilge pumps." Two manual pumps, an electric pump, and a shower sump pump (essentially a micro bilge pump). None are ABYC compliant -- but the boat has gone 24 years, 25,000 nm, 2 trans atlantics, and hasn't sunk yet.


None of the pumps discharge above the heeled water line, none have vacuum breaks, none have seacocks. Worse, none of the (unvented) loops are above the heeled water line so even with vacuum breaks the can still backflow. The manual pumps have double internal check valves, so I'm not too worried. The electric pump has a check valve inline, that hasn't presented any issues in the 5 years/8,000nm I've owned it. The shower sumpbox puzzles me -- it is a centrifugal pump, no check valves, and I'm 100% certain it gets fully under the water line at least at times.


I'm not looking to fix these factory issues, as they have worked so far. Although I still don't like it.


I'm considering adding a second electric bilge pump, the biggest I can. Either a 4000GPM 12V, or going really big at 120V -- 3/4hp or bigger. The DC one could get a float switch, the 120V version would have to be 100% manual intervention. I'd like to at least look at ABYC compliance, or at the very least greatly minimize flooding concerns.


My problem, not unique to me, is that the area against the hull, below the deck, is filled with lockers. The deck is the ABYC definition of the water line (and on my boat, putting the rail in the water is not unheard of). A vacuum breaker and loop would have to be higher than the deck, or in the main cabin!


I'm thinking that given the "emergency only" use of this pump, I should forgo all efforts to prevent backflow, and install a thru hull/seacock and leave it permanently closed. In use, open valve (with likely backflow) and immediately power the pump -- water will flow the right way.


The ideal solution is to get the outlet above the heeled water line, but that means the transom and that is a challenging 25' run (with attendant flow losses). I ran 3/4" PEX from there forward for hydronic heat, and even that was a huge challenge.


So, after all that, what solutions have others made for retrofitting a compliant bilge pump discharge in typical cruising sailboats?

[rslifkin]

How is your cockpit drained? The Saga 43 is a semi-open transom, right? If so, what about just dumping the output of the "oh ****" pump into the cockpit (perhaps angled down so the occupants don't get sprayed). That will keep it from getting submerged when heeled severely as well as making an effective bilge alarm for the helmsman.

I wouldn't want a seacock on a bilge pump as in my mind, the thing should be pumping as soon as a water problem shows up, no delay while I react and start doing things.

[MicHughV]

Having experienced some " sinking" moments in the past, the best advice I can give anyone regarding bilge pumps is to fit an "alarm" to the float switch.
You want to know the instant it goes off, why it goes off.
My alarm can wake the dead, which is just want I wanted. I want someone in the cockpit to hear it should it go off as well as anybody below decks.
I also have a switch wired into the circuit to switch the sound off as the alarm will cause an ear splitting wail.
I routinely check the bilge pumps, float switches, etc these days, almost daily in fact, such as my paranoia has made me do.

[markxengineerin]

fit an "alarm" to the float switch.

Or add a dedicated alarm (or two!) that go off a couple inches above the normal float switch. That way they only go off when something is very wrong and the alarm is justified. I think it's one of the cases where redundancy is justified, although I only have one alarm myself.

[meirriba]

Consider our somewhat different solution.
I have purchased a large electric pump.
Gave it two large hoses. One shorter for sucking water and one longer for discharge overboard.
Added long (and thick) electric cable, with two connectors at the end. One normal 12v car plug, and additional crocodile clamps that can be connected directly to any battery I choose.
This mobile setup lives in an ready accesible locker in the cockpit.

[MicHughV]

I've been thru' some pretty knarly weather, big eye-poppin' waves breaking over the boat, etc, etc, but nothing gets your attention quite like seeing swirling water over the floorboards and not knowing where it's coming from.
Bilge pumps tend to be " out of sight, out of mind" thing, until the doodoo hits the fan, but should be the #1 item that needs regular inspection, maintenance, etc.

[sailingharry]

Originally Posted by meirriba

Consider our somewhat different solution.
I have purchased a large electric pump.
Gave it two large hoses. One shorter for sucking water and one longer for discharge overboard.
Added long (and thick) electric cable, with two connectors at the end. One normal 12v car plug, and additional crocodile clamps that can be connected directly to any battery I choose.
This mobile setup lives in an ready accesible locker in the cockpit.

I have long considered this, but much bigger. 12V bilge pumps are simply centrifugal pumps, and we have been building centrifugal pumps for generations. 12V pumps have significantly higher advertised output for a given electric power input -- and I don't believe it for a nanosecond. If our flimsy plastic crap were really 50 or 100% more productive than the classic home sump pump, the home sump pump builders would notice and make changes. And then, to make matters worse, the largest 12V pumps top out at around 15A, or 180W, or 1/4 hp.


So, I as I read about lots of "slow motion sinkings" (boats that take 12, 24, or more hours to sink), I think that they could be saved by use of a BIG pump. Not an installed one, but a portable one, like you suggest, that you pull out when you need it (and not gas for numerous reasons). The vast majority of well equipped boats these days have inverters, that have excellent reliability records. So, I wold think that a 1.5hp dirty water submersible pump and a 20' chunk of 2" discharge hose would be an excellent $300 investment. It would have to be stored someplace (probably an inconvenient place) and might take 1/2 an hour to pull out and plug in, but for damage that is too big for a "bilge pump" but small enough to actually save, 1/2 hour is not a problem.


Sure, downsides. If your batteries or inverter are under water, you are toast. If you are sucking down 1kW (1.5hp), or 100A, your batteries won't last long unless you still have a running engine with a good alternator. But if those supporting systems are working well, you can move more water in 10 minutes than you can move in a day with a 5 gallon bucket!

[rslifkin]

Originally Posted by sailingharry

I have long considered this, but much bigger. 12V bilge pumps are simply centrifugal pumps, and we have been building centrifugal pumps for generations. 12V pumps have significantly higher advertised output for a given electric power input -- and I don't believe it for a nanosecond. If our flimsy plastic crap were really 50 or 100% more productive than the classic home sump pump, the home sump pump builders would notice and make changes. And then, to make matters worse, the largest 12V pumps top out at around 15A, or 180W, or 1/4 hp.


So, I as I read about lots of "slow motion sinkings" (boats that take 12, 24, or more hours to sink), I think that they could be saved by use of a BIG pump. Not an installed one, but a portable one, like you suggest, that you pull out when you need it (and not gas for numerous reasons). The vast majority of well equipped boats these days have inverters, that have excellent reliability records. So, I wold think that a 1.5hp dirty water submersible pump and a 20' chunk of 2" discharge hose would be an excellent $300 investment. It would have to be stored someplace (probably an inconvenient place) and might take 1/2 an hour to pull out and plug in, but for damage that is too big for a "bilge pump" but small enough to actually save, 1/2 hour is not a problem.


Sure, downsides. If your batteries or inverter are under water, you are toast. If you are sucking down 1kW (1.5hp), or 100A, your batteries won't last long unless you still have a running engine with a good alternator. But if those supporting systems are working well, you can move more water in 10 minutes than you can move in a day with a 5 gallon bucket!

The home sump pumps are more powerful, but if you look at the specs, that often comes in the form of dramatically more head pressure capacity. They'll move a bit more water at open flow, but they'll handle 20+ feet of head (the bilge pumps won't) and will move more water at moderate amounts of head. Those design differences are also why the bilge pumps tend to be much physically smaller.

A big sump pump on board is a good idea as a crash pump, the challenge is often fitting one in a useful place in the boat. There's also the concern for a way to trigger it automatically. I'm a fan of having as much pumping capacity as possible automatically triggered. The sooner you start moving water and the more you can move, the longer you have to find and do something about the problem in a flooding emergency.

On my own boat, I've got small pumps in the forward and aft bilges (which have some capacity to overflow to the engine room bilge). The aft bilge really needs another, bigger pump when I can figure out how to get one in there (poor access and limited space) as there are multiple potential flooding sources back there. The engine room bilge is well covered. 1 small Whale supersub for nuisance water, a Rule 1100 (alarmed) mounted slightly higher, and then a big Rule 3700 mounted up higher as a 3rd level pump (this one is mounted higher than ideal as it's too wide to fit more than slightly down into the keel sump). Based on the manufacturer specs for flow vs head loss, I estimate the 3 pumps in the engine room should move at least 50 gallons per minute (total) in the real world.

For a really big pump, there's always the option of an electric non-submersible trash pump or big centrifugal pump (like one of the Pacer pumps) mounted somewhere in the boat with plumbing and valves to a couple of areas on board. Then there's no need to pull it out, lay out hoses, etc. Just open the appropriate intake valve and turn it on.

[sailingharry]

Originally Posted by rslifkin

How is your cockpit drained? The Saga 43 is a semi-open transom, right? If so, what about just dumping the output of the "oh ****" pump into the cockpit (perhaps angled down so the occupants don't get sprayed). That will keep it from getting submerged when heeled severely as well as making an effective bilge alarm for the helmsman.

I wouldn't want a seacock on a bilge pump as in my mind, the thing should be pumping as soon as a water problem shows up, no delay while I react and start doing things.

The cockpit has an open transom. Because it is not full width, there drains in the aft corers, but that simply addresses nuisance water -- any significant water goes out the transom.


I've often thought of a big pump and a hose to the cockpit, but that would have to be set up -- the hose would have to run through the cabin to the hatch, and would be too big to keep permanently attached. It would be nearly impossible to run a hose permanently without having a significant section in "free air" because there is no cabinetry or lockers against the cockpit wall. It could be done, but would be super ugly.

[MicHughV]

So here is an interesting problem for this forum to digest.

Modern design boats tend to have flat bottomed hulls, much like my Beneteau. For sure, there are many things about this concept I appreciate, but it there is one glaring issue with this.

The "bilge" on my boat, is a shoebox size indentation in the keel. That's it....that's all bilge you get. The bottom of the hull is maybe 9-10" below the floorboard. The bottom of the "bilge" indentation is perhaps 4" below that.

There is no room in this "bilge" area for a bilge pump of any type. What you do get is a hose led to a " water pump" type of pump located under a settee. That hose has about a 5/8" inside diameter. Another large " hose", about 1.5" inside diameter is led to manual bilge pump located in a cockpit locker. Nothing else besides those two hoses can fit in the " bilge". The hoses are both fitted with an end grating filter gizmo to prevent anything besides water from entering the hoses. This is all good and well, but further reduces the flow capacity that can go thru' these hoses..

The float switch is located elsewhere. It is mounted to a piece of wood, glued to the hull, adjacent to the "bilge".

Ok, so that is the basic setup.

Here is the problem, when the boat is heeled over, any water inside the boat does not go towards the bilge, no indeed, it goes to the low side of the boat, where it will accumulate unnoticed until a considerable amount of water has collected there. There is no way to get this water out, other than to bring the boat upright, so that the water can find it's way to the " bilge".

So......what to do ???

[rslifkin]

Originally Posted by MicHughV

So here is an interesting problem for this forum to digest.

Modern design boats tend to have flat bottomed hulls, much like my Beneteau. For sure, there are many things about this concept I appreciate, but it there is one glaring issue with this.

The "bilge" on my boat, is a shoebox size indentation in the keel. That's it....that's all bilge you get. The bottom of the hull is maybe 9-10" below the floorboard. The bottom of the "bilge" indentation is perhaps 4" below that.

There is no room in this "bilge" area for a bilge pump of any type. What you do get is a hose led to a " water pump" type of pump located under a settee. That hose has about a 5/8" inside diameter. Another large " hose", about 1.5" inside diameter is led to manual bilge pump located in a cockpit locker. Nothing else besides those two hoses can fit in the " bilge". The hoses are both fitted with an end grating filter gizmo to prevent anything besides water from entering the hoses. This is all good and well, but further reduces the flow capacity that can go thru' these hoses..

The float switch is located elsewhere. It is mounted to a piece of wood, glued to the hull, adjacent to the "bilge".

Ok, so that is the basic setup.

Here is the problem, when the boat is heeled over, any water inside the boat does not go towards the bilge, no indeed, it goes to the low side of the boat, where it will accumulate unnoticed until a considerable amount of water has collected there. There is no way to get this water out, other than to bring the boat upright, so that the water can find it's way to the " bilge".

So......what to do ???

Keep the existing small pump in the tiny sump for nuisance water. Then mount 3 big pumps with floats next to them for water removal in the event of a problem. One on the centerline, then one off to each side (so it would be approximately at the bottom in the heeled scenario).

Basically the idea is to put a pump anywhere water might accumulate in a normal use situation if that water won't drain to a central bilge.

[MicHughV]

Yes, I've thought of doing something like that, but it will be quite a project. Each pump would need to be fitted with a one-way valve so as to prevent water from running back, etc. From Pump to discharge outlet location would be 12' or so, but discharge pipe would have to bend, twist and turn, etc. May end up with a 20' hose
My past experience with one-way valves makes me suspect of their viability.
Have seen float switches which are tiny self contained units.

[sailingharry]

Originally Posted by MicHughV

Have seen float switches which are tiny self contained units.

I used two of these on my last boat (two pumps, 1 very small, one as big as I could fit). Never had any issues.
https://www.amazon.com/Attwood-4801-.../dp/B001O0D6LU
My current boat has a WaterWitch, no problems in 5 years/8,000nm.