Inverter Bilge query

Caboteur · Mar 8, 2023

If you foresee using this with the engine running, would it not be simpler and less cumbersome to « t » the sea-water intake with a hose to the bilge? Turn it « on » when needed?

JohnShannon · Mar 8, 2023

It is likely a less efficient system than a DC 1800 pump the same water flow your batteries die sooner.

DArcy · Mar 8, 2023

If I was in a situation where I needed to run an 1800 GPH pump I'm not sure I would want to rely on keeping the inverter dry and fumbling with alligator clips. The hose is not the main concern with that setup. Having a coiled up hose for an emergency bilge pump could be ok.
I'd get a proper DC bilge pump with the long hose then at your leisure find a way to T it into the existing outlet.

tfox2069 · Mar 8, 2023

Scratching my head at the setup. Typically a boat has with both a manual and automatic bilge pump. The automatic bilge pumps I've seen on boats are 12v and wired directly to your batteries - not AC and through an inverter. Also, the 12v bilge pumps I've seen on boats are plumbed to an above the waterline thru hull. I would imagine a garden hose to the open transom would be suboptimal to say the least. And you want a 12v bilge pump to have a float switch so that if you do get water in the bilge it starts pumping immediately, and not when you turn it on - which is likely to be a long time after the ingress starts if you're busy in the cockpit and not noticing the floorboards are sloshing around.

This article is helpful:

Everything You Need To Know About Your Boat's Bilge Pump | BoatUS

Benny17441 · Mar 8, 2023

It would be a good and significant addition as long as the limitations and the intended use are understood. Let's accept that this pump would be easily overwhelmed by any significant intrusion of water. These pumps are bench rated without a load, do not anticipate getting anywhere near the rate of 1800 GPH which will depend on the size, length and lift of the discharge hose plus the inefficiencies of the electric motor as heat builds up. In an emergency the first order of business is to stop or significantly slow down the water intrusion and having the materials and tools aboard to be able to perform the fix. That is what safety is all about. These pumps are intended to buy a little time to perform a repair and then after the fact, to remove the accumulated water as quickly as possible to be able to get promptly underway to a safe landing. I would prefer a permanent installation as precious time lost deploying it may obstruct performing a timely fix.

Don S/V ILLusion · Mar 8, 2023

Jeff2650 said:
Hello all,
I just added a 1800gph AC bilge pump with a garden hose

I didn’t read much past that.
Do you realize what the flow rate is limited to by the diameter of a garden hose?

Ralph Johnstone · Mar 8, 2023

Jeff2650 said:
I just added a 1800gph AC bilge pump with garden hose to be placed temporarily as a discharge to my open transom and connect it to an aft mounted 1000w inverter that can easily be connected to my twin bank of batteries close by with attached alligator clips in the event of water intrusion occurs while underway.

I've have to ask, what is it that you are so unreasonably fearful of that you are going to pack a 26 ft. vessel with enough equipment to the point where it interferes with the enjoyment of your boat.

Always post a "dependable" watch when moving, have paper charts for the area your sailing in, have a GPS, all of your mandatory safety equipment, and nothing is going to happen.

Scott T-Bird · Mar 9, 2023

I don't understand your circumstance. Do you already have a primary bilge pump and a manual emergency bilge pump and you want to add a 3rd pump? Or do you NOT have a primary bilge pump (DC operated) and you need to install one. The AC pump connected to an inverter makes no sense when the inverter depends on your batteries. You'd have to explain why you have an AC pump. Are you leaving this set-up in place with the hose running across the deck all the time? This is a very curious question.

capta · Mar 9, 2023

I had a similar system on my 53 footer, but I had 3 much larger a/c pumps, with 1.5" discharge lines and a genset. Never mind 2 rule 3k 12vdc pumps and two sump pumps. Even with all that, the table below may give you some idea of how much water you must be able to remove to stay afloat.

tfox2069 · Mar 9, 2023

An "easy backup" to your manual pump would be a 12v bilge pump with a float switch plumbed properly to a thru hull above the waterline. No alligator clips, no inverter, and no delay in pumping when water starts to appear in the bilge. I would not adovcate plumbing an electric bilge pump thru your manual bilge pump line - you'll want two separate pumps emptying through two separate hoses if there's an emergency.

I believe what one contributor was suggesting was to T off of your raw water intake hose to your engine and evacuate bilge water via that path since you propose to have the engine running if there's a water ingress emergency. I've seen such a suggestion in the event of a dire emergency, but more along the lines of once the water got high enough disconnecting the hose to your raw water pump and letting that evacuate water as your engine pumps it out as a THIRD path to extricate water, in ADDITION to your manual bilge pump and your 12v electric bilge pump. But that's for an extreme emergency, and not a routine way you'd want to evacuate bilge water. Why? Because there's crap in everyone's bilge and you don't want that getting pumped into the engine's cooling system. If it did, it might just clog up the cooling passages and stop the engine you're using to get to safety quickly. Kind of counterproductive and risky unless its a dire emergency.

If you're looking at the inverter setup you describe as a backup to a manual and a properly installed 12v bilge pump, maybe that's OK. But not in lieu of the 12v one. I'm not going to speak for anyone else on here, but that seems to be the consistent sentiment I'm reading on here, or seeing inferred.

Scott T-Bird · Mar 9, 2023

Best practice is to have separate hoses for both the primary and emergency bilge pumps. I'm sure some boats have them combined, but it's not a good idea. I find it odd that you don't have a primary bilge pump with an automatic switch so that your bilge will activate when necessary and you aren't there. Is it because the boat is primarily designed as a trailer sailer? Which begs the question, do you keep your boat in the water or on a trailer?

If you are on a trailer, my suggestion would be that perhaps you are over concerned about pump capacity and you can rely on your manual pump when necessary (which seems to be, well, never). If you have your boat on a mooring or slip, I'd suggest that you need a primary pump and automatic switch and a separate hose for it. DC of course. I can't think of any reason why you would use an AC pump on an inverter. My Starwind 27 had a primary pump but not an emergency manual pump. It bothered me to some extent but not enough to add one ... I never did before I sold it.

Do you have an outboard or an inboard diesel? If you don't keep your boat in the water, perhaps it wouldn't be a bad idea to run a hose off your engine intake back to the bilge with a T and a valve. That way, if you need to pump water as you are running your engine, you can simply open the valve (and close the intake) and let her pump. That wouldn't replace a primary pump, though, if you keep her on a slip or mooring.

Don S/V ILLusion · Mar 9, 2023

Jeff2650 said:
All, thanks for your responses, good advice on many levels. I wasn't clear in my original post. The boat ((only)) came with and ((only)) has a single emergency/manual pump to be accessed while in the cockpit. I check its function regularly while at the dock.

The purpose of the inverter was to establish an easy back up in the event of water intrusion, obviously after trying to mitigate the water from entering the vessel-this would likely suffice, unless catastrophic in which case other measures would be taken.
That said, one post mentioned (Y-ing) it to the existing evacuation hose, ironically enough it is the same diameter as the marine garden hose in question, and utilizing the same single hose existing the bilge to evacuate the water.
Which brings to question, wouldn't passing water throguh the manual diaphragm hand pump via the electric pump down the line, compromise the manual pump?

A 3/4 inch garden hose restricts flow to 10 gpm at 40 psi. Likely your bilge pump can never approach that pressure. So attaching a 1800gph bilge pump to a hose capable of handling less than 600 gph is futile.

if your hose is smaller, has bends or has any head which is inevitable, the actual discharge rate is further compromised.
if you want redundancy, that’s laudable, however, what you describe doesn’t buy you much.

Captain Larry-DH · Mar 9, 2023

Don S/V ILLusion said:
I didn’t read much past that.
Do you realize what the flow rate is limited to by the diameter of a garden hose?

Something to consider for your backup emergency pump - I have a 4000 GPH DC bilge pump that uses a 1-5 or 2" outlet hose. This could be mounted in your bilge pre-wired with the hose attached. Even if you don't want to make such a large thru-hull you could coil the hose, and make it long enough to secure outside of your companionway. It draws 15A but if you can run your engine the alternator should be able to keep up.
Something like this Johnson Pumps 4000 GPH High Capacity Bilge Pump

kappykaplan · Mar 9, 2023

Scott T-Bird said:
Best practice is to have separate hoses for both the primary and emergency bilge pumps.

jrussnogle · Mar 9, 2023

I just can’t see 12v bilge pumps of any size, let alone a manual pump (how many strokes you think you’ll last) as valuable for anything other than nuisance water. Check out the chart from capta and do the math. If you have a puncture below the waterline of anything more than an inch diameter you’re better off radioing a mayday, grabbing life jackets and an EPIRB. Otherwise consider a prop shaft driven pump, such as from Fast Flow that has minimum flow rate of 24,000 gal/hour. larger pumps are available. Just my 2 cents. Or, as has been suggested, spend your money on materials that will give you a chance to block off intruding water.

Project_Mayhem · Mar 9, 2023

Jeff2650 said:
Which brings to question, wouldn't passing water throguh the manual diaphragm hand pump via the electric pump down the line, compromise the manual pump?

Your manual hand pump is going to restrict the flow of the electric one. The garden hose is probably undersized for that pump as well. Your AC pump on an inverter will draw a lot more power and reduce how long your pumps can go for. Bilge pumps are meant to pump out residual water, not keep up with a hole in your boat. My marina leaves abandoned boats in the water over the winter. Despite the fact that Lake Michigan will see 8ft waves coming up to the shore, the boats stay afloat. Assuming that you moor in significantly better conditions, you should be fine as long as you keep up with maintenance. Your paranoia is normal for a new boater and will disappear with time and experience

jssailem · Mar 11, 2023

jrussnogle said:
spend your money on materials that will give you a chance to block off intruding water.

Interestingly, US Navy training of all personnel regarding flooding is done in very wet simulators.

Although noble, when a ship starts sinking, not many really want to go down with it. While precautions are always in place to help ensure that doesn't happen, life can throw a big wrench into things.

The USS Buttercup, located at Farrier Firefighting School in Norfolk, has been helping Sailors work around those wrenches by ensuring Sailors are trained to keep their ship afloat.

Although it has a funny name, the training is serious. Elements of an actual flood are mimicked perfectly: cold, dark, hectic. Water is flooding in from every which way, pitting Sailors against real world scenarios they could find themselves in at the drop of a hat.

"Overall, the importance of the Buttercup is to give a real life scenario, or a real life situation, to pipe patching, bulkhead repair and shoring," said Damage Controlman 1st Class Kreig Newton, an instructor at Farrier. "Stuff you will see and be able to do in case you hit something."

A simulator may be a bit much for our sailboats but we can develop a plan, practice the skills and discuss the issues with crew.

I’m remembering the dinghy training when first learning to sail. We had to flip the Lido 14 over, right it and bail it out before being allowed to take it sailing in San Diego Bay. Those were heady days.

Inverter Bilge query

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